Phase plug and acoustic lens for direct radiating loudspeaker

A phase plugs or acoustic lens improves the directional audio performance of a loudspeaker. Application of the improved directional audio performance to a sound system in a listening area may improve the performance of the audio system. Configuration of the acoustic lens or phase plug may include both symmetrical and asymmetrical features to provide an improved frequency response and directivity. The improved loudspeaker may provide improved an improved listing location, for example, in a vehicle.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to loudspeakers, and more particularly, to direct radiating loudspeakers and modifying the directivity of sound radiation.

2. Related Art

Automotive sound systems currently suffer from different tonal balance in different listening positions due to the directivity characteristics of direct radiating loudspeakers. Sound energy radiating into the surrounding ambient space within an automobile may result in different tonal balance characteristics depending upon the relative position of the listener to the loudspeaker.

A typical loudspeaker may have a low directivity at low frequencies. The speaker's response may have increased directivity and/or nulls in the frequency response at higher frequencies. Accordingly, the speaker will not provide the same frequency response or tonal quality for each listener depending upon the listener's relative position to the speaker. The response difference may result in reduced high frequency output at some listening positions. Additionally, the response at angles away from a primary axis of the speaker may have a different character from the response on the primary axis. Typically, the different character of the off-axis performance cannot be corrected electronically.

SUMMARY

To overcome the aforementioned difficulties, a need exists for an improved loudspeaker that provides sound radiation having very low and uniform directivity over a relatively wide frequency range. Lower, more uniform directivity may be obtained by using a phase plug to guide sound energy from the sound producing surface of a speaker, through an aperture with a smaller area than the sound producing surface of the speaker. Depending upon the features of the phase plug, the phase plug may cause nulls in the response of the speaker assembly at higher frequencies.

One example assembly includes a speaker coupled to an acoustic lens. The union of the acoustic lens to the speaker form a substantially air tight or resistant seal. The seal may be created by using a gasket between the acoustic lens and the speaker. Alternatively, the seal may be created by gluing the acoustic lens to the speaker.

An acoustic lens may typically include a centrally located aperture. The centrically located aperture may be configured to move resonance points of the acoustic lens. The centrally located aperture may have various shapes. Example shapes include circular, elliptical, etoile, estoile, triangular, or star-like. The shapes may be irregular shaped. The lengths of the sides of the shapes may be identical or non-identical. The aperture may be substantially two dimensional or three dimensional. Apertures may be created by a grouping of perforations that form an effective aperture.

To reduce distortion and insertion loss, the acoustic lens may further include vents, supplementary apertures, or auxiliary apertures. Similar to the central aperture, each supplemental aperture may have various shapes.

The examples described herein provide both apparatuses and methods to improve the directivity performance of a sound system. In addition, application of unique structural formations and asymmetric features provides improved directivity while reducing the effects of nulls in the frequency response at higher frequencies.

In one example, a sound system includes a loudspeaker having a mounting feature and a sound generation surface. A phase plug may be mounted to the mounting feature of the loudspeaker to provide improved directional audio performance. In at least one example, an acoustic lens may include a first member and a second member coupled together to form a passageway from the speaker sound generation surface to ambient air. The first member may also include a first surface and a second surface. The first surface and the second surface may unite to form a first edge defining a perimeter of the first member. A union of the first surface and the second surface may also form an internal lip defining petals around an orifice. The second surface may further include protrusions surrounding the orifice. The first member and the second member may be attached by way of support members. The support members may protrude from the second surface and each support member may be attached to one of the petals.

The third surface may include support points, where each support member is joined to one of the support points so that the second surface confronts the third surface. Each of the petals may include a deflection away from the third surface. The second member includes a third surface and a fourth surface. The third surface further may include a protuberance having a zenith oriented towards the orifice.

The fourth surface may further include a beveled edge. The beveled edge may define the perimeter of a depression substantially centered in the fourth surface. The fourth surface may be oriented to face the sound generation surface of the speaker. The fourth surface may be sculptured to provide a gap between the sound generation surface and phase plug. The gap between the sound generation surface and the phase plug allows movement of the sound generation surface without interference.

The third surface may further include a plurality of the protrusions, where each protrusion has a first protrusion face and a second protrusion face. Each first protrusion face may be beveled to face the sound generation surface of the speaker. Each second protrusion face may be beveled to substantially face the third surface. The third surface further may also include channels. Each of the channels may be positioned between two of the plurality of protrusions.

The phase plug may include openings oriented to face the sound producing surface. Each opening may be formed by the second surface, the third surface, and two of the support members. Two of the supports may be adjacent. Each of the openings may define or form a cross-sectional area. In addition, at least one of the cross-sectional areas of one of the openings may have a cross-sectional area different from a cross-sectional area of at least one of the other openings. The differences in cross-sectional area may provide an asymmetrical feature to provide different resonant behavior from each opening.

The protuberance of the third surface may be shaped in a substantially conical form to aid the deflection of sound energy through the phase plug. The orifice of the first member may include a cross-section shaped as an etoile or estoile. Alternatively, the orifice may include a star-like, estoile, or etoile shape or appearance. In at least one example, the star-like, estoile, or etoile shape may be symmetrical or have an even number of radiating points. Other examples may include a star, estoile, or etoile shape having an asymmetrical property or an odd number of radiating points. The star-like, estoile, or etoile shape may provide pathways for sound energy to propagate and thereby provide improved frequency response or improved directivity performance. The asymmetrical properties provide different pathways for sound energy to propagate through the phase plug, which distributes resonances over a range of frequencies. Each pathway has a different resonance frequency. The distribution of resonances may provide an overall improved frequency response for the system.

Another example of the phase plug is configured to improve the directional audio performance from a sound system. In particular, the phase plug may be configured to provide improved directional audio performance in an automobile or vehicle. The phase plug may include a first member having a first surface and a second surface. The union of the first surface and second surface form a first edge that forms a perimeter of the first member. A second union of the first surface and second surface forms an internal lip to form protrusions positioned about an orifice of the phase plug. Each protrusion may include an edge. The plurality of edges may combine to form one or more openings, through or in the first member. The openings through or in the first member may include a slice or wedge. The wedges or slices may form one or more openings through the first member to create or define the orifice. Intersections of each protrusion with one of the adjacent protrusions may further form or delineate a vertex for a slice or wedge shaped opening in or through the first member. The first member may further include support members emanating from the second surface.

The phase plug may include a second member attached to the first member. The second member may include a third surface and a fourth surface, where the third surface faces the second surface. The third surface may also include a dome feature surrounded by support positions. Each of the support members may be joined to the third surface at one of the support positions to attach the first member to the second member. In addition, each of the protrusion of the first member may include a deflection away from the third surface.

The phase plug may also include apertures, where each aperture is formed by the combination of the second surface, the third surface, and two of the plurality of support members. The apertures may be connected to the orifice of the phase plug to permit sound energy to radiate through the apertures and out of the orifice.

The phase plug may also be configured such that each vertex of each slice or opening is associated with one of the apertures. In some examples, at least one slice or opening is asymmetrically aligned with one of the apertures associated with at least one slice. In other examples, multiple slices are asymmetrically aligned with one of the associated apertures. The alignment of the apertures and slices work in combination to form channels for sound to pass through the phase plug. Each channel may propagate acoustic energy in a different manner. As a result, the combined outputs of the respective channels provide an improved sound power response. The combined outputs may also provide improved directivity.

In still another example, an apparatus to improve the directional audio performance from a sound system includes a loudspeaker having a mounting feature and a sound generation surface. The sound system may also include a phase plug mounted to the mounting feature of the loudspeaker. The phase plug may include a first member and a second member. The first member may include a first surface and a second surface that includes a first union and a second union. The first union of the first surface and the second surface form a perimeter edge. The second union of the first surface and the second surface form an internal lip to define protrusions around an orifice of the phase plug. The orifice of the phase plug may be positioned to radiate into the ambient air of a vehicle or automobile. The second surface may further include protuberances positioned about the orifice. The first member may further include support members protruding from the second surface.

The second member of the phase plug may further include a third surface and a fourth surface, where the third surface further has support positions. Each support member may be joined to one of the support positions. The phase plug further includes openings oriented to face the sound generation surface of the speaker. Each of the openings may be in communication with or connected to the orifice to provide a path for sound energy to move from the surface of the loudspeaker and through the phase plug. Each of the openings may be formed by the third surface, two of the support members that are adjacent, and at least two of the protuberances. The fourth surface may also be configured to face the sound generation surface of the speaker.

Another example further includes a phase plug to improve the directional audio performance from a sound system. The phase plug may include a first member including a first surface and a second surface. A first union of the first surface and the second surface form a first edge that forms or defines a perimeter of the first member. A second union of the first surface and the second surface may form an internal edge that forms or defines protrusions, where the protrusions form a boundary or perimeter of an aperture. The protrusions may conform substantially to the surface of a conical frustum. The conical frustum may have a zenith that forms a plateau. The aperture may include at least one opening at the zenith of the conical frustum. The aperture may include slices or wedges through the conical frustum to create a flower petal-like structure that is symmetric about a central axis and having an asymmetrical number of petal-like members. Each of the slices may radiate from the opening at the zenith of the conical frustum between an adjacent pair of the protrusions.

In addition, the first member may further include support members emanating from the second surface. A second member may include a third surface and a fourth surface. The third surface may include support points, and each support member may join to one of the support points. The phase plug may also include apertures. Each of the apertures may be formed by the second surface, the third surface, and two of the plurality of support members, where two of the plurality of support members are adjacent.

Another example of a phase plug to improve the directivity of a speaker includes a first member and a second member. The first member may include a first surface and a second surface joined to create a peripheral edge. The first and second surface may also include a union to form an interior lip. The interior lip may include an aperture edge formed by a set of substantially parabolic curved edges delineated in three dimensions to form an aperture. The aperture may have substantially parabolic curved edges that further delineate or form wedged shaped openings radiating outwardly from a central opening.

The second member of the phase plug may include a third surface and a fourth surface. The third surface may be oriented to substantially face the second surface, where the union of the third surface and the fourth surface form a perimeter edge.

Support members may join the first member and the second member, where each support member includes a first end attached to the second surface, and each support member further includes a second end attached to the third surface. The second and third surfaces may be separated by a void or opening to allow passage of sound energy through the phase plug. Each of the openings may be formed by the second surface, the third surface, and two of the support members, where two of the support members are adjacent, where each wedged shaped opening is oriented towards one of the openings and where each wedge shaped opening projects beyond the perimeter edge of the second member.

The orientation and surface of the wedge shapes may be configured to provide additional channeling effects to improve the directivity of the sound emanating from the orifice. The aperture of the phase plug may have an effective cross-sectional area. Each of the openings may have an opening cross-sectional area. The openings cross-sectional area may be combined to form an effective opening cross-sectional area. The aperture effective cross-sectional area and the effective opening cross-sectional area may include different ratios as compared to the area of the sound generation surface. Adjustments to the ratio may lessen air noise and other distortion effects.

In some examples, a summation of the opening cross-sectional area of each of the openings is about the same or equal to the effective cross-sectional area of the aperture. The aperture effective cross-sectional area and the effective opening cross-sectional area may be adjusted to either a compressive or non-compressive ratio to lessen air noise. Additionally, a summation of the opening cross-sectional area may be between two and ten times smaller than the sound generation surface. Alternatively, the summation of the opening cross-sectional area may be any size as compared to the sound generation surface depending upon directivity, sound power, and fidelity requirements of the sound system.

Another example includes an acoustic lens for improving directivity performance of a speaker assembly. The acoustic lens may include a member including a first surface and a second surface. The first surface and the second surface may unite to form a first edge to define a perimeter, where the perimeter includes a mounting feature. The first surface and the second surface may further unite to form a plurality of perforations arranged to define an effective aperture through the member. The member may further include a solid portion that lies between the effective aperture and the mounting feature, and where at least some portion of the solid portion lies substantially in a first plane.

In addition, the mounting feature may include a foot feature that lies in a second plane. The foot feature may be conformed to mate with a speaker to form a substantially air tight seal between the speaker and the foot feature of the member. A portion of the effective aperture may include a dome surface having an apex and a dome base, where the apex lies in the first plane, and the dome base lies close to a third plane, and where the third plane lies between the first plane and the second plane. The member further includes a substantially conical segment that lies between the dome base of the dome surface and the solid portion. The substantially conical segment of the acoustic lens may also include at least a portion of the substantially conical segment includes a portion of the plurality of perforations.

Also, the plurality of perforations of the acoustic lens may be arranged to form a border of the effective aperture, and where the outer border of the effective aperture includes at least one of an etoile shape, an estoile shape, and a star-like shape. Alternatively, or in addition, the dome surface may be formed as a convex dome. The connection between the substantially conical segment and the convex dome may also form a contour or fold.

In another example of the acoustic lens, the plurality of perforations arranged to define the effective aperture through the member are further arrange to form an imperforated portion centrally located in the effective aperture.

An acoustic lens for improving directivity performance of a speaker assembly may include a member including a first surface and a second surface, where the first and second surface unite to create a first union. The first union forms an internal lip to define a plurality of protrusions surrounding an orifice. In addition, the first surface and the second surface further unite to form a perimeter of the member, where the perimeter includes a mounting feature.

The mounting feature may include a foot portion conformed to mate with a speaker to form a substantially air tight seal between the speaker and the foot portion of the member. Each of the protrusions include an outer contour that intersects with the outer contour of an adjacent one of the protrusions to form a plurality of outer vertices with respect to a central point of the orifice, where the protrusions further includes interiorly located vertices with respect to the central point of orifice.

In some examples, the interior vertex of the plurality of protrusions and outer vertices of the orifice combine to form an irregular etoile shape. A first outer vertex of the outer vertices is located at a first outer vertex distance from the central point of the orifice, and a second outer vertex of the outer vertices is located at a second outer vertex distance from the central point of the orifice. In addition, a first interiorly located vertex of the plurality of interiorly located vertices is located a first distance from the central point of the orifice, while a second interiorly located vertex of the plurality of interiorly located vertices is located at a second distance from the central point of the orifice.

In other examples, the first surface and the second surface may unite to form a plurality of perimeters of a plurality of auxiliary apertures. At least one of the auxiliary apertures may be located in a portion of one of the protrusions. Otherwise, at least one of the auxiliary apertures may be an effective auxiliary aperture formed by a plurality of perforations within a perimeter of the at least one of the auxiliary apertures. One or more of the perimeters of one of the auxiliary apertures defines a cross-sectional area that may have a shape of an etoile-like form, an estoile-like form, or a circle-like form. Alternatively, one of the perimeters of the auxiliary apertures may define a cross-sectional area that includes a triangular-like shape or a circular-like shape. In addition, the summation of each cross-sectional aperture surface area may be related to a determined volume displacement through the summation of the combined cross-sectional areas of the orifice and all of the auxiliary apertures.

An assembly of a speaker mated to an acoustic lens may be optimized to improve directivity and power output of the speaker. The acoustic lens may include a first surface and a second surface. The first surface and the second surface may unite to form an internal lip to define an orifice that is centrally located in the acoustic lens, where the orifice includes a primary cross-sectional area. The first surface and the second surface further unite to form a perimeter of the acoustic lens, where the perimeter includes a mounting feature. The mounting feature may include a foot portion conformed to mate with the speaker to form a substantially air tight seal between the speaker and the foot portion of the acoustic lens. In addition, the first surface and the second surface further unite to form a plurality of supplementary lips to define a plurality of supplementary apertures.

The supplementary lips of the acoustic lens may define cross-sectional areas for each of the supplementary apertures and the cross-sectional area of each of the supplementary apertures includes a triangular-like shape. The triangular-like shape may include a base and a vertex. Each of the supplementary apertures may be oriented to locate the vertex of the triangular-like shape nearest to the orifice and to locate the base of the triangular-like shape nearest to the perimeter of the acoustic lens. The supplementary lips may define cross-sectional areas of each of the supplementary apertures, where the supplementary apertures are evenly distributed around the internal lip of the orifice. The supplementary lips of the acoustic lens may define cross-sectional areas for each of the supplementary apertures. The cross-sectional areas of all the supplementary apertures may be identical.

The speaker of the assembly may include a diaphragm. The summation of the cross-sectional areas of the supplementary lips may be selected based upon a cross-sectional area of the orifice and a volume displacement of the diaphragm to minimize distortion and insertion loss. In addition, the cross-sectional area of the orifice may be selected based upon a volume displacement of a diaphragm of the speaker.

Another acoustic lens for improving directivity performance and frequency response of a speaker assembly includes a speaker and an acoustic lens mated to the speaker. The acoustic lens may include a first surface and a second surface. The first surface and second surface may unite to form a first edge to define a perimeter, where the perimeter includes a mounting feature. The first and second surface may also unite to form a plurality of perforations arranged to define an effective aperture through the acoustic lens. The acoustic lens may also include a solid portion that lies between the effective aperture and the mounting feature, where at least some portion of the solid portion lies substantially in a first plane. The mounting feature of the acoustic lens may include a foot feature that lies in a second plane. The foot feature is conformed to mate with the speaker to form a substantially air tight seal between the speaker and the foot feature of the acoustic lens. Also, a portion of the effective aperture may include a convex dome surface having an apex and a dome base, where the apex that lies close to the first plane, and the convex dome base lies close to a third plane, and where the third plane lies between the first plane and the second plane.

The acoustic lens further may include a substantially conical segment that lies between the convex dome base of the dome surface and the solid portion that surrounds the effective aperture. At least a portion of the substantially conical segment may include a portion of the plurality of perforations. The plurality of perforations may be arranged to form a border of the effective aperture, and where the outer border of the effective aperture includes at least one of an etoile shape, an estoile shape, and a star-like shape.

Another speaker assembly may include a speaker and an acoustic lens. The speaker may include a mounting ring and a diaphragm, where the speaker includes a volume displacement of the diaphragm “Vd”, where the volume displacement is a volume of air that is displaced by movement of the diaphragm. The acoustic lens including a centrally located aperture having a cross-sectional aperture surface area, “S”, where the acoustic lens is mated to the mounting ring of the speaker to a substantially air tight seal. The cross-sectional aperture surface area of the speaker may be configured to obtain a desired sound pressure level (SPL) insertion loss, IL, of the acoustic lens with respect to the speaker within a range of frequencies, where the insertion loss

IL≈0.01⁢(VdS)2+0.001⁢(VdS)
[in dB] within a desired range of frequencies.

Another speaker assembly for improved directivity performance of a radiating speaker may include a speaker and an acoustic lens. The acoustic lens may include a first surface and a second surface, where the first surface and the second surface unite to form a perimeter of the acoustic lens. The perimeter of the acoustic lens may include a mounting feature, and where acoustic lens is mated to the mounting feature to form a substantially air tight seal between the speaker and acoustic lens. In addition, the first surface and the second surface unite to define a perimeter of an aperture substantially located in a central location of the acoustic lens. The central location of the acoustic lens may be located approximately centered over a sound producing surface of the speaker.

The effective aperture of the acoustic lens may include a plurality of perforations arranged to define the perimeter of the effective aperture through the acoustic lens. The perimeter of the effective aperture of the acoustic lens may form an etoile-shaped form.

DETAILED DESCRIPTION OF THE PREFERRED EXAMPLES

Phase plugs may provide a way to achieve low directivity over wider bandwidth than previously possible. The lower directivity may enable sound systems designs such as automotive sound system designs that have about the same tonal balance at each listening position within a listening area, such as in a vehicle. Alternatively, phase plugs may be used to improve the tonal balance at particular listening positions.

Improved loudspeaker directivity may be obtained by locating a phase plug in front of the diaphragm of a loudspeaker. Sound radiates from the diaphragm of the loudspeaker and passes through multiple spaced slots in the phase plug to communicate sound from the diaphragm to the surrounding environment. Unlike previous uses of phase plugs to direct sound into a horn, the sound energy radiates from the phase plug into an ambient environment without a horn.

InFIGS. 1-6, Phase plug100includes a first member102and a second member104. The first member102includes a first surface106. The first member102includes a second surface406; the second surface406inFIG. 4and described in greater detail below. The second member104includes a third surface110. The second member104further includes a fourth surface410, which is also inFIG. 4. InFIG. 1, the first member102and second member104are joined by a first support member112, second support member502(inFIG. 5), third support member504(inFIG. 5), fourth support member114, and fifth support member116.

A first union of the first surface106and second surface406inFIG. 4creates an outer perimeter edge108. A second union of the first surface106and second surface406also forms an interior edge or a lip120. The lip120includes a curved surface in three dimensions forming the perimeter of a first petal130, a second petal132, a third petal134, a fourth petal136, and a fifth petal138.

The first petal130includes a first petal edge210, a first deflection212, and a second deflection214. The first deflection212, second deflection214, and first petal edge210of the first petal130enclose a first petal surface216. The first petal edge210and second deflection214of the first petal130enclose a second petal edge218. The first petal130may have a zenith at about the location of the second petal surface218.

The second petal132includes a first petal edge220, a first deflection222, and a second deflection224. The first deflection222, second deflection224, and first petal edge220of the second petal132enclose a first petal surface226. The first petal edge220and second deflection224of the second petal132enclose a second petal surface228. The second petal132may have a zenith at about the location of the second petal surface228.

The third petal134includes a first petal edge230, a first deflection232, and a second deflection234. The first deflection232, second deflection234, and first petal edge230of the third petal134enclose a first petal surface236. The first petal edge230and second deflection234of the third petal134enclose a second petal surface238. The third petal134may have a zenith at about the location of the second petal surface238.

The fourth petal136includes a first petal edge240, a first deflection242, and a second deflection244. The first deflection242, second deflection244, and first petal edge240of the fourth petal136enclose a first petal surface246. The first petal edge240and second deflection244of the fourth petal136enclose a second petal surface248. The fourth petal136may have a zenith at about the location of the second petal surface248.

The fifth petal138includes a first petal edge250, a first deflection252, and a second deflection254. The first deflection252, second deflection254, and first petal edge250of the fifth petal138enclose a first petal surface256. The first petal edge250and second deflection254of the fifth petal138enclose a second petal surface258. The fifth petal138may have a zenith at about the location of the second petal surface258.

The first support member112may be fluidly joined to interior surfaces of first petal130. The fifth support member116may be fluidly joined to interior surfaces of fifth petal138. The fourth support member114may join fluidly to an interior surface of fourth petal136. The third support member504may be fluidly joined to an interior surface of the third petal134. The second support member502may fluidly join to an interior surface of the second petal132

The first petal edge210and second petal edge220intersect to form a first notch310. The second petal edge220and third petal edge230intersect to form a second notch320. The third petal edge230and fourth petal edge240intersect to form a third notch330. The fourth petal edge240and fifth petal edge250intersect to form a fourth notch340. The fifth petal edge250and first petal edge210intersect to form a third notch350.

The edge or lip120forms an opening or an orifice140. The petals130,132,134,136, and138may be arranged about the orifice140. The orifice140may be centered approximately in the center of the first member102. The petals130,132,134,136, and138may be equally distributed around the orifice140. In addition, petals130,132,134,136, and138may have substantially similar symmetries. In other examples, petals130,132,134,136, and138may be distributed unevenly about the orifice140. In addition, in other examples, the petals130,132,134,136, and138may have an asymmetric or non-uniform size, thickness, appearance, or shape or a combination thereof. Alternatively, some examples may have an even number of petals while other examples may have an odd number of petals.

As a non-limiting example, the orifice140includes a generally star-like shape, estoile, or etoile configuration in cross-section. Orifice140includes a central aperture360. The orifice140of the first member102further includes a star-like shaped, an estoile shaped, or an etoile shaped configuration having five radiating slices312,322,332,342, and352. In other examples, the star-like shaped, the estoile shaped, or the etoile shaped configuration may have an odd number of radiating slices or wedges. Alternative examples may have an even number of radiating slices or wedges.

A first radiating slice312may be formed or defined by the first petal edge210, the first notch310, the second petal edge220, and the central aperture360. The first radiating slice312projects from the central aperture360towards first notch310and terminates at a first radiating end point314.

A second radiating slice322may be formed or defined by the second petal edge220, the second notch320, the third petal edge230, and the central aperture360. The second radiating slice322projects from the central aperture360towards the second notch320and terminates at a second radiating end point324.

A third radiating slice332may be formed or defined by the third petal edge230, the third notch330, the fourth petal edge240, and the central aperture360. The third radiating slice332projects from the central aperture360towards the third notch330and terminates at a third radiating end point334.

A fourth radiating slice342may be formed or defined by the fourth petal edge240, the fourth notch340, the fifth petal edge250, and the central aperture360. The fourth radiating slice342projects from the central aperture360towards the fourth notch340and terminates at a fourth radiating end point344.

A fifth radiating slice352may be formed or defined by the fifth petal edge250, the fifth notch350, the first petal edge210, and the central aperture360. The fifth radiating slice352projects from the central aperture360towards the fifth notch350and terminates at a fourth end point354.

The star-shaped, estoile shaped, or etoile shaped configuration may further include five radiating end points314,324,334,344, and354. The first radiating point314is formed by the first notch310. The second radiating point324is formed by the second notch320. The third radiating point334is formed by the third notch330. The fourth radiating point344is formed by the fourth notch340. The fifth radiating point354is formed by the fifth notch350.

Other examples of the phase plug100may include differing numbers of intersections or slices to form orifice140. The orifice140may also be configured to have a substantially inverted polygon like shape. The orifice may also be configured to include a contoured shape resembling an ellipse or circular form. Alternatively, the orifice may include a square, rectangular or boxy form or feature. Still other examples of the orifice may have include a polygonal feature. In addition, the orifice may be configured in a generally asymmetric geometry. The petals130,132,134,136, and138may be rounded, substantially elliptical, parabolic, non-uniform, or asymmetric in form. The petal edges210,220,230,240, and250may come to a substantially thin or tapered edge.

InFIG. 4, the second surface406includes mounting collar420formed between an interior edge422and perimeter edge108of the first member102. The mounting collar420may be configured to interface the phase plug100with a speaker assembly. The interior edge422may be differentiated from the second surface406by an internal surface424configured to sit above the surface of the speaker in the speaker assembly.

The third surface110may also include a raised or dome feature150having a zenith154. The raised feature may further include a protuberance or protrusion152projecting from the third surface110. The protuberance or protrusion152may include the zenith154of the third surface. The protrusion152may have a conical form. In other examples, protuberance152may include a convex surface rising from the base of a conoid to the zenith154. Alternatively, protuberance152may have a convex surface. In still other examples, the protrusion152may have a truncated form including a substantially flat portion at the zenith154.

The union of a third surface110and a fourth surface410may form an edge432. The fourth surface410may further include a first sloping surface434and a second sloping surface438. The first sloping edge434and second sloping surface438may form a rounded surface or edge436configured to sit above the sound producing portion of a speaker. Rounded surface436may be beveled or sculpted to minimize turbulence in the air volume produced by the sound generating surface of a speaker.

Fourth surface410may further include a depression440enclosed by the rounded surface436. The depression440may have a bowl or concave feature that reaches a nadir442. The nadir442may be located substantially in the center of the fourth surface410. Nadir442may be located opposite the zenith154of the raised portion150of the third surface110.

InFIGS. 5-6, the second surface406may further include five protrusions510,520,530,540, and550. The first protrusion510may be collocated with the respective first support member112. The second protrusion520may be collocated with the second support member502. The third protrusion530may be collocated with the third support member504. The fourth protrusion540may be collocated with the fourth support member114. The fifth protrusion550may be collocated with the fifth support member116.

InFIG. 5, the support members112,114,116,502, and504are symmetrically collocated with respect to the center of the respective protrusions510,540,550,530, and520. Even so, the support members may be skewed so as to not be symmetrically collocated with respect to the respective protrusions510,540,550,530, and520. In addition, at least one of the support members may not be collocated with respect to the protrusions.

The second surface406further includes four additional protrusions560,562,564, and566, which are not collocated with one of the support members. The sixth protrusion560is positioned between the first protrusion510and the second protrusion520. The seventh protrusion562is positioned between the second protrusion520and the third protrusion530. The eighth protrusion564is positioned between the third protrusion530and the fourth protrusion540. The ninth protrusion566is positioned between the fifth protrusion550and the first protrusion510.

The sixth protrusion560, seventh protrusion562, eighth protrusion564, and ninth protrusion566each includes a first and second channel face602and an interior face604. The first protrusion510, the second protrusion520, the third protrusion530, the fourth protrusion540, and the fifth protrusion550each include a first and second channel face602, a beveled face606, a first interior face608, and a second interior face610.

A first channel620is formed between the channel face602of the first protrusion510and the channel face602of the sixth protrusion560. A second channel622is formed between the channel face602of the sixth protrusion560and the channel face602of the second protrusion520. A third channel624is formed between the channel face602of the second protrusion520and the channel face602of the seventh protrusion562. A fourth channel626is formed between the channel face602of the seventh protrusion562and the channel face602of the third protrusion530. A fifth channel628is formed between the channel face602of the third protrusion530and the channel face602of the eighth protrusion564. A sixth channel630is formed between the channel face602of the eighth protrusion564and the channel face602of the fourth protrusion540. A seventh channel632is formed between the channel face602of the fifth protrusion550and the channel face602of the fourth protrusion540. An eighth channel634is formed between the channel face602of the fifth protrusion550and the channel face602of the ninth protrusion566. A ninth channel636is formed between the channel face602of the first protrusion510and the channel face602of the ninth protrusion566.

The first member102and the second member104in combinations with the first support member112, the second support member502, the third support member504, the fourth support member114, and the fifth support member116form five openings,570,572,574,576, and578, that pass through to the orifice140. A dotted line, inFIG. 5, shows the relative position of orifice140relative to the structures of the phase plug100when viewed from the fourth surface410.

The first opening570may be formed by a portion of the second surface406, the first support112, the second support502and the second member104form a first opening570that passes through to the orifice140(a dotted line onFIG. 5). The portion of the second surface406that forms the first opening570includes a portion of the first protrusion510, a portion of the second protrusion520, and the sixth protrusion560. In addition, opening570may further include the first channel620and the second channel622.

The second opening572may be formed by a portion of the second surface406, the second support502, the third support504, and the second member104. The second opening572may further include the third channel624and the fourth channel626. The second opening572may be in communication with the orifice140.

The third opening574may be formed by a portion of the second surface406, the third support member504, the fourth support114, and the second member104. The third opening574may further include the fifth channel628and the sixth channel630. The third opening574may be in communication with the orifice140.

The fourth opening576may be formed by a portion of the second surface406, the fourth support114, the fifth support members116, and the second member104. The fourth opening576may include the seventh channel632. The third opening576may be in communication with the orifice140.

The fifth opening578may be formed by a portion of the second surface406, the first support112, the fifth support members116, and the second member104. The fourth opening578further includes the eighth channel634and ninth channel636. The third opening576is in communication with the orifice140.

By way of a non-limiting example, inFIGS. 5 and 6, the first opening570, the second opening572, the third opening574, and the fifth opening578each define cross-sectional areas that are substantially equal. However, the fourth opening576is depicted as having a smaller cross-sectional area. As a result, the openings provide an asymmetric feature to receive sound emitted by the sound producing surface of a speaker. Alternative examples of the phase plug may include other asymmetrical features to the input surface including, but not limited to, each opening having a different cross-sectional area, a combination of differing cross-sectional areas, or positioning at least one of the support members to be skewed from the center of a protrusion.

Referring toFIG. 7, the petal130includes a first interior petal surface716that corresponds to the first petal surface216. The petal130further includes a second interior petal surface718, which corresponds to the second petal surface218. The first interior petal surface716and the second interior petal surface718may be joined to the first support member112.

The petal132includes a first interior petal surface726that corresponds to the first petal surface226. The petal132further includes a second interior surface728that corresponds to the second petal surface228. The first interior petal surface726and the second interior petal surface728may be joined to the second support member502.

The petal134includes a first interior petal surface736that corresponds to the first petal surface236. The petal134further includes a second interior surface738that corresponds to the second petal surface238. The first interior surface736and second interior surface738may be joined to the third support member504.

The petal136includes a first interior petal surface746that corresponds to the first petal surface246. The petal136further includes a second interior surface748that corresponds to the second petal surface348. The first interior petal surface746and the second interior petal surface748may be joined to the fourth support member114.

The petal138includes a first interior petal surface756that corresponds to the first petal surface356. The fifth petal138further includes a second interior surface758that corresponds to the second petal surface358. The first interior petal surface756and the second interior petal surface758may be joined to the fifth support member116.

The first notch310of the first radiating slice312impinges upon the interior surface604of protrusion560. Likewise, the second notch320of the second radiating slice322impinges upon the interior surface604of protrusion562. The third notch330protrudes into an area about the eighth protrusion564without impinging upon the interior face604of the eighth protrusion564. Likewise, the fifth notch350protrudes into an area about the protrusion566without impinging upon the interior surface of the protrusion566. Notch340is substantially aligned with seventh channel632.

InFIG. 8, a first axis M runs between viewpoints M1and M2.FIG. 8further depicts a second axis N running between viewpoints N1and N2. Another cross-sectional view, inFIG. 9, is depicted as a vertical slice along the first axis M.

InFIG. 9, the seventh channel632is substantially aligned with the fourth opening576, the fourth notch340and fourth radiating slice342. The alignment of the seventh channel632with the fourth opening576, the fourth notch340and fourth raiding slice342forms a substantially direct radiating path or opening940from the input of the fourth opening576to the orifice140. The substantially direct opening940communicates sound energy entering the fourth opening576to the ambient920beyond the orifice140. The raised or domed feature150of the third surface110in combination with protrusion152tends to reflect the sound energy received through the fourth opening576through the orifice140.

InFIG. 9, the protuberance152may project into or towards the orifice140. Accordingly, the zenith154of the protuberance152may rise above a portion of the first surface106. As a non-limiting example,FIG. 9also depicts that the zenith154may be positioned between the level of the fourth notch340and the second petal surface228of the second petal132. Some examples of the third surface110may include a portion of domed feature150positioned above a portion of the lip120. In other examples, the domed feature150is located below the lip120while the zenith154of protrusion152is located above at least a portion of lip120.

InFIG. 10, the third opening574substantially aligns with the third notch330and the third radiating slice332. The alignment of the third radiating slice332with the third opening574and the third notch330forms a substantially direct radiating path or opening1010from the input of the third opening574to the orifice140. Similar to the substantially direct channel910, the substantially direct channel1010communicates sound energy entering the third opening574to the ambient920beyond the orifice140. The raised or domed feature150of the third surface110in combination with protrusion152tends to reflect the sound energy received through the third opening574through the orifice140.

The protuberance152may project into the orifice140. As a result, the zenith154of the protuberance152may rise above a portion of the first surface106or a portion of lip120. As another non-limiting example,FIG. 10depicts that the zenith154may be positioned between the level of the third notch330and the second petal surface218of the first petal130. Some examples of the third surface110may include a portion of domed feature150positioned above the second petal surface218. In other examples, the domed feature150is located below the lip120while the zenith154of protrusion152is located above at least a portion of lip120.

In contrast, the first opening570substantially aligns with a portion of the first petal130. The first support member112is skewed from the symmetrical center of the first petal130. As a result, the combination of the first interior petal surface718and third surface110form a channel1020, which is in communication with orifice140. Channel1020directs sound energy from the first opening570toward the orifice140. A portion of the sound energy directed through channel1020may be reflected off the third surface110. In part, some portion of the sound energy directed through opening1020may be reflected off the raised or dome feature150or the protuberance or protrusion152.

The overall effect of the alignment of the radiating slices312,322,332,342, and352with the structures forming the openings570,572,574,576, and578is to form various asymmetric or non-uniform structures and features with respect to the flow of sound energy through the openings570,572,574,576, and578into orifice140. The non-uniform and asymmetric structure provides multiple paths for sound energy to propagate from the sound producing surface of the speaker to the surrounding ambient through the orifice140. Because each path may be configured to provide a slightly different frequency response, the effect of nulls in the phase plug response may be minimized while optimizing the directivity response provided by the overall speaker assembly.

FIG. 11further depicts phase plug100from the perspective of the first surface106. The relative position of the support members112,114,116,502and504are depicted as dashed lines positioned about orifice140. The first support member112provides structural support for the first petal130. The support member112may be positioned off an axis of symmetry of the first petal130. The fourth support member114provides structural support for the fourth petal136. Similar to support member112, support member114may be positioned off an axis of symmetry of the fourth petal136.

Referring back toFIG. 9, the end point344of the fourth notch340may extend up to or beyond the edge432of the second member104. As a result, the fourth notch340may overlap the fourth opening576. InFIG. 10, the end point334of the third notch330may extend up to or beyond the edge432. As a result, the third notch330may overlap with the third opening574.

Referring toFIGS. 3 and 11, viewing the assembly of the first and second member from the perspective of the first surface106, the end points314,324,334,344, and354may each extend beyond the deflections212,222,232,242, and252. Alternatively, the first end point314may extend past the edge432of the second member104to create a first passage1110between the first surface106and the fourth surface410. The second end point324may extend past the edge432to create a second passage1120through phase plug100. The third end point334may extend past the edge432to create a third passage1130between the first surface106and the fourth surface410. The fourth end point344may extend past the edge432to create a third passage1140between the first surface106and the fourth surface410. And, the fifth end point354extends past the edge432to create a fifth passage1150between the first surface106and the fourth surface410. Each of the passages,1110,1120,1130,1140, and1150, may provide a means for sound energy to be directed from the sound producing surface of a speaker (not shown) to the surrounding ambient without incurring a physical encumbrance.

Even so, to provide other aspects of asymmetry and the frequency response of the phase plug, other examples may have only some or none of the end points may extend pass edge432. The depth of the over lap of each notch310,320,330,340, and350with the openings,270,272,274,276, and278, may be different so as to change the frequency response of each slice or passageway through phase plug100. WhileFIG. 11depicts each of the five radiating slices312,322,332,342, and352as having substantially uniform widths and shapes, other examples may include radiating slices with different widths or shapes.

Furthermore, even thoughFIGS. 1-11depict petals having substantially uniform shapes and widths, other examples may include at least one petal having a non-uniform width, a non-uniform shape, an asymmetric form, a non-uniform curvature, and/or a combination thereof. Still other examples may provide other variations, including but not limited to the height above or below a single surface, thickness, uniformity, width, or taper of edges, to at least one or more of the petals130,132,134,136,138, and/or petal edges210,220,230,240, and250to further alter the response of the phase plug radiating into an ambient.

Adjusting the distance between the support members may provide for additional asymmetrical or non-uniform openings. As a result, the distance between the first support member112and second support member114may be located relatively close in proximity relative to the other proximate support members. Alternatively, varying distances between the supports or the alignments of the supports with respect to other features may be included to provide a more uniform or desirable response or change the position of a peak or a null in the response of the phase plug100or overall speaker assembly.

WhileFIGS. 1-11depict an odd number of protrusions such that the number of protrusion or channels contained in each opening is different, other examples of the phase plug100may include the same number of protrusions or channels. Other examples of the phase plug100may include a number of protrusions such that the number of protrusions or channels in each opening is the same.

FIG. 12depicts the third surface110of the second member104. The third surface110includes a first ledge1200that encumbrances the raised or domed feature150. The third surface110further includes a first support position1212, a second support position1202, a third support position1204, a fourth support position1214, and a fifth support position1216. The first support position1212may be configured to interconnect with or fluidly join to support member112. The second support position1202may be configured to interconnect with or fluidly join to support member502. The third support position1204may be configured to interconnect with the third support member504. The fourth support position1214may be configured to interconnect with or fluidly join to support member114. The fifth support position1216may be configured to interconnect with or fluidly join to support member116. The interconnection of each respective support member,112,502,504,114, and116, may interconnect or join with the corresponding support position1212,1202,1204,1214, and1216by virtue of an ultrasonic soldering process. Alternatively, the respective support member and support position may be attached using a spin friction process or adhesive.

For descriptive purposes only,FIG. 12further includes a first axis M defining a vertical plane or slice M. The first axis is further defined by points of view/end points M1and M2. From viewpoint M2the vertical plane M passes approximately through the midpoint between the fourth support position1214and the fifth support position1216. From the point M1the vertical plane M also passes approximately through the symmetrical center of the second support position1202. The axis M passes through protuberance or protrusion152and zenith154.

For further descriptive purposes only,FIG. 12also includes a second axis N defining a vertical plane or slice N. The second axis N is further defined by points of view/end points N1and N2. The second axis N also passes through the protuberance or protrusion152and zenith154. From viewpoint N2, the vertical plane N passes between the third support position1204and the fourth support position1214. From viewpoint in N1, the vertical N passes between the first support position1212and the second support position1202.

FIG. 13depicts the position of the fourth surface410of the second member104. The dashed lines depict and correspond to the first support position1212, the second support position1202, the third support position1204, the fourth support position1214, and the fifth support position1216.

FIGS. 14 and 15depict the phase plug along the first axis M from the perspective of the viewpoint M1. From the viewpoint of M2, the protuberance152protrudes above a portion of the first surface106and into orifice140. The relative positioning of support members114and116in combination with the second member104and second surface406of the first member102may create the fourth opening576. The fourth opening576may be positioned symmetrically below the fourth slice342and opposite the location of petal132. The third opening574is formed by support members114and504in combination with the second support member104and second surface406of first member102. The fifth opening578is formed by support members112and116in combination with the second support member104and second surface406of first member102.

InFIG. 14, the third opening576encompasses a cross-sectional area1476. The second opening574encompasses a cross-sectional area1474. The fifth opening578encompasses a cross-sectional area1478. By inspection, the cross-sectional area1476of the fourth opening576may be less than the cross-sectional area1478of the fifth opening578or the cross-sectional area1474of the third opening574. The differences in cross-sectional area of the openings contribute to the asymmetry of the phase plug, which correlates with improved the high frequency response of the phase plug100.

In addition, the combination of the fourth radiating slice342with the opening576provides a degree of asymmetry with respect to the flow of sound energy through the surface area1476to the orifice140. In contrast, the combination of the third opening574and the fourth petal136combine to provide another degree of asymmetry. Likewise, the combination of the fifth opening578with the fifth petal138provides another degree of asymmetry. In addition to the added degrees of asymmetry, the variance in structures provides different path lengths for the sound energy. The different path lengths further provide for varying high frequency responses that tend to prevent null points from emerging or dominating the frequency response of the phase plug100.

In contrast,FIG. 15depicts, from the viewpoint M1, a second view of the phase plug100also along the first axis M. The first opening570encompasses a cross-sectional area1570. The second opening572encompasses a cross-sectional area1572. By inspection, the cross sectional areas1570and1572may have the same or approximately the same surface area. The support member502may be positioned to divide the second petal132into symmetrically equal portions.

The first opening570combines with radiating slice312, first petal130, and second petal132to form a channel for sound energy to pass from the first opening570to the orifice140. The second opening572combines with radiating322and second petal132, and third petal134to form a path or channel for sound energy to pass from the opening572to orifice140. As depicted, the channel associated with the first opening570may be a mirror image of the channel associated with the second opening572. In other examples, the respective channels may include different openings and/or slice geometries or sizes.

The relative positing of the support member112,114,116,502, and504to the petal openings may also provide addition symmetrical or asymmetrical geometries that may be adjusted to provide different frequency response characteristics of the phase plug100.

FIG. 16depicts, from the viewpoint N1, a first view of the phase plug100along the second axis N. The opening572encompasses a cross-sectional area1672. The second opening272combines with the second radial slice322and first petal130to foam a channel for passing sound energy through the cross-sectional area1672to orifice140. A portion of second opening272may be aligned with the second radial slice322. Another portion of the second opening272may be aligned with the first petal130.

FIG. 17depicts, from the viewpoint N2, a second view of the phase plug100along the second axis N. In particular,FIG. 17provides a second perspective of the arrangement of the fifth opening578with respect to the fourth petal136, the third petal134, and the fifth radial slice352. In the contrastingFIGS. 16 and 17, the fifth opening578ofFIG. 17may be a mirror image of the second opening572ofFIG. 16. Alternatively, the respective support members of each respective opening may be adjusted to increase or decrease respective cross-sectional areas of each opening. By adjusting the cross-sectional areas of each opening, the symmetric imagery of the respective openings may be modified to optimize the desired frequency response of the phase plug. Alternatively, the symmetric imagery of the respective openings may be adjusted to optimally move or place nulls in the frequency response of the phase plug to provide an optimal or desired frequency response of the phase plug.

FIG. 18depicts the phase plug100from the perspective of the second member104. The second member104is attached to the first member102via support members. The combination of the first member102and second member104with the support members112,114,116,502, and504create openings for sound energy or air flow to pass through phase plug100. The location of nadir442in combination with depression440provides a cavity to be positioned above a central portion of a speaker. In other examples, the fourth surface may be formed to provide a minimum cavity or project outward to provide for a consistent or uniform air gap between the sound producing surface of a speaker and the surface of the phase plug that is positioned proximate to the speaker. The mounting collar420may be conformed to form a lip or edge of the phase plug100to interface with a speaker in a speaker assembly. Mounting collar420may further include features, not shown, to lock or detachably secure the phase plug in place upon being incorporated into a speaker assembly.

FIG. 19depicts a cross-sectional view of a speaker assembly1900including a speaker1902with a conical diaphragm. The speaker1902includes a dustcap1903attached to a cone1904at an interface1906. The cone1904attaches to surround1908. The surround1908rest on a basket1910of the speaker1902.

The speaker assembly1900further includes phase plug1912, which is another example of the phase plug100. Phase plug1912includes a first member102and a second member104. The first member102and second member104are attached by support members (not shown). The fourth surface410is positioned over the dustcap1903and cone1904.

The first sloping surface434, the second sloping surface438and the rounded surface or edge436may be positioned proximate to the interface1906. The curvature or relief of the edge436may be formed to minimize turbulence of air moving across or through the volume between the fourth surface410and the dustcap1903. The fourth surface410further includes a domed or curved portion positioned above the dustcap1903. The curved portion has a nadir442positioned proximate the center of the dustcap1903and opposite the apex or zenith154of protrusion152.

The first member102includes a first petal1930and first protrusion1932having a first face1934and a second face1936. The edge432of the second member104combines with the first face1934to form a passage1938. Passage1938permits sound energy to pass from the surface of the cone1904and dustcap1903into the interior of the phase plug1912. The dome feature150and protrusion152of the third surface110combines with the first petal1930to form a channel for sound energy to pass through the aperture140.

The first member102also includes a second petal1940and a second protrusion1942having a first face1944and a second face1946. The edge432of the second member104combines with the first face1934to form a passage1948. Passage1948permits sound energy to pass from the surface of the cone1904and dustcap1903into the interior of the phase plug1912. The dome feature150and protrusion152of the third surface110also combines with the second petal1940to form a channel for sound energy to pass through the aperture140.

In contrast to the cross-sectional view inFIGS. 10 and 11, the cross-section of phase plug1912depicts substantially similar passages1938and1948. In addition, the channels formed by the petals in relationship to the domed portion150and protuberance152are depicted as having a substantially symmetrical form.

The speaker inFIG. 19may be combined with any of the phase plug examples as inFIGS. 1-18as well as the alternate examples described herein. Furthermore, while the speaker inFIG. 19includes a conical diaphragm, other diaphragm types may be combined with the phase plugs described herein.

FIG. 20depicts a top view and cross-sectional view of acoustic lens2000. The acoustic lens2000may be configured to mount over the sound producing surface of a speaker (not shown). The acoustic lens2000includes first surface2002and second surface2004. The first surface2002and the second surface2004form a union to create an exterior edge or lip2006. The exterior lip or edge2006may be configured to rest upon a mounting feature of the speaker. The first surface2002and second surface also form a union to form an interior lip or edge2008. The interior lip2008delineates an aperture2010, where the interior lip2008delineates a cross-sectional area of aperture2010.

As a non-limiting example, the aperture2010includes an axisymmetric opening in or near the central location of the first surface2002and the second surface2004. The interior lip or edge2008may have a thickness of between 0.5-2.5 mm thick.

In other examples, the interior lip2008delineates a cross-sectional area of the aperture2010that includes about 15% or more of the surface area of the acoustic lens2000. The acoustic lens2000further includes features to mate to a frame of a speaker (not shown) while providing clearance for the moving diaphragm assembly of the speaker. The acoustic lens2000may be composed of various rigid materials of varying flexibility. Illustratively, in one example, acoustic lens2000may be composed of plastic. In other examples, the acoustic lens2000may be composed of metal. In still other examples, the acoustic lens2000may be composed of other suitable materials or composite materials.

The second surface2004is mounted proximate to the radiating surface of a speaker, not shown. The aperture2010of the acoustic lens2000effectively reduces the radiating area of the speaker. The smaller radiating area delineated by the interior lip2008reduces the directivity of the speaker, which provides a more uniform sound pressure level frequency response (spectral balance) over a wider coverage area and to a higher frequency.

Additionally, the stiffness of the volume of air between the diaphragm of the speaker, (mounted proximate to the second surface2004), and the acoustic lens2000resonates with the mass of the air in the aperture2010(Helmholtz resonance). As a result, the sound pressure level of the speaker in the frequency range increases around this resonance frequency. Above the Helmholtz resonance frequency range, the volume of air between the diaphragm and the acoustic lens acts as an acoustic lowpass filter, reducing the sound pressure level of the speaker. This effect is typically most prominent in the octave immediately above the Helmholtz resonance frequency range.

Above the Helmholtz resonance frequency range, other resonances occur due to standing waves within the volume of air between the diaphragm and the acoustic lens2000(“cavity resonances”). The cavity resonances cause peaks and dips in the sound pressure level frequency response measured at a position located on the side of the acoustic lens2000corresponding to the first surface2002.

The reduced radiating area of the aperture typically reduces the sound pressure level (“insertion loss”) and increases the sound pressure distortion. These effects can occur throughout the operating bandwidth of the speaker, but are typically most significant and easily identified in the one or two octaves immediately below the Helmholtz resonance frequency range. These effects worsen (increase) as the aperture area decreases.

FIG. 21depicts a top view and cross-sectional view of the acoustic lens2100. The acoustic lens2100may be configured to mount over the sound producing surface of a speaker (not shown). The acoustic lens2100includes a first surface2102and a second surface2104. The first surface2102and the second surface2104form a union to create an exterior edge or lip2106. The exterior lip or edge2106may be configured to rest upon a mounting feature of the speaker. The first surface2102and second surface also form a union to form an interior lip or edge2108. The interior lip2108delineates an aperture2110, where the interior lip2108delineates a cross-sectional area of the aperture2110.

The interior lip2108may be configured to include edges of various geometric shapes. Illustratively, the interior lip2108may be configured to resemble an etoile, an estoile, or a star-like shape having a plurality of vertices2132and2134. Illustratively, some vertices, similar to the vertex2134, may project into the aperture2110. Other vertices, similar to the vertex2134, may project outwardly from a center of aperture2110. Although depicted as a star-like shape, an estoile shape, or a etoile shape including six radiating points, other examples include an etoile, an estoile, or star-like shaped aperture having an odd number of radiating points.

Some examples of the acoustic lens2100may have a thickness of between about 0.5-2.5 mm. The aperture2110may be non-axisymmetric about the center of the body of acoustic lens2100. The cross-sectional area delineated by the interior lip2108of the aperture2110is typically 15% or more of the surface area of the acoustic lens2100. In some examples, the aperture2110may include an odd—typically prime—number, of non-axisymmetric features. The non-axisymmetric features may extend to an outer diameter whose dimensions are typically similar to the dimensions of the outer diameter of the diaphragm of a speaker mounted proximate to the second surface2104, which is not shown. For example, the acoustic lens2100includes five triangular features radiating from a central aperture. The five triangular features may be joined to form a “five pointed star” shaped aperture. The acoustic lens2100may include features to mate to a frame and be further configured to provide a clearance to accommodate movement of a diaphragm assembly of the speaker. Similar to acoustic lens2000, the acoustic lens2100may be composed of plastic or metal, but can be composed of other suitable materials.

Performance of the acoustic lens2100is similar to the acoustic lens2000, except the cavity resonances are suppressed and/or distributed. This typically provides a higher and smoother sound pressure level at high frequencies. Additionally, the directivity typically changes more smoothly with frequency, but may be higher in some frequency ranges.

FIG. 22depicts a top view and cross-sectional view of an acoustic lens2200. The acoustic lens2200is similar to the acoustic lens2000. The acoustic lens2200may be configured to mount over the sound producing surface of a speaker (not shown). The acoustic lens2200includes the first surface2202and the second surface2204. The first surface2202and the second surface2204form a union to create an exterior edge or lip2206. The exterior lip or edge2206may be configured to rest upon a mounting feature of the speaker. The first surface2202and the second surface also form a union to form an interior lip or edge2208. The interior lip2208delineates an aperture2210, where the interior lip2208delineates a cross-sectional area of aperture2210.

Also similar to the acoustic lens2000, the acoustic lens2200may be configured to locate the aperture2210as an axisymmetric opening in or near the central location of the first surface2202and second surface2004. The interior lip or edge2208may have a thickness of between 0.5-2.5 mm thick.

In addition, to the axisymmetric opening of aperture2210, the first surface2202and the second surface2204may unite to form additional interior lips2212,2214,2216,2218, and2220, where each of the vent lips2212,2214,2216,2218, and2820delineate respective vent apertures2222,2224,2226,2228, and2230. InFIG. 22, each respective aperture is located about the axisymmetric opening2210. In some examples, the vent apertures2222,2224,2226,2228, and2230may be distributed proportionally. In other examples, the vent apertures2222,2224,2226,2228, and2230may be distributed approximately the same distance from the central axis of aperture2210. However, in other examples, the vent apertures2222,2224,2226,2228, and2230may be distributed at varying distances from the center of aperture2210.

The surface area of the aperture2210may be typically 15% or more of the surface area of the acoustic lens2200. Additionally, there may be a number of axisymmetric “vent” apertures2222,2224,2226,2228, and2230located close to or on an outer diameter whose dimensions are typically similar to the dimensions of the outer diameter of the diaphragm. In some configurations, the acoustic lens2200includes an odd number of vent apertures. In other examples, the acoustic lens2200includes a prime number of vent apertures.

Each of the vent apertures includes a cross-sectional area delineated by respective vent lips. The combined cross surface area of the “vent” apertures may be less than or equal to the surface area of the aperture2210. The acoustic lens may include features to mate to a frame of a speaker assembly and provides sufficient clearance from the moving parts of the speaker diaphragm assembly. The acoustic lens may be typically composed of plastic or metal, but could be composed of other suitable materials.

Performance of the acoustic lens2200is similar to the acoustic lens2100. However, the combination of the aperture2210and the vent apertures2222,2224,2226,2228, and2230increase the effective aperture area provided to the acoustic lens2200. Accordingly, the acoustic lens2200exhibits a higher Helmholtz resonance frequency. In addition, the acoustic lens2200may have a wider Helmholtz resonance frequency range and a lower Helmholtz resonance sound pressure level increase.

The directivity of the acoustic lens2200is typically higher from the Helmholtz resonance frequency to the frequency with a corresponding wavelength approximately equal to pi (π) times the effective radius of the central aperture. Above this frequency, the sound pressure level and directivity are typically essentially unchanged. The sound pressure “insertion loss” and distortion are typically reduced.

FIG. 23depicts a top view and a cross-sectional view of an acoustic lens2300. The acoustic lens2300is formed similar to acoustic lens2100, where like numbers and features correspond. In addition, the acoustic lens2300further includes the vent apertures2322,2324,2326,2328,2329, and2330similar to the vent apertures of the acoustic lens2200.

InFIG. 23, the aperture2310includes an even number of star points. However, similar to other disclosed examples, the aperture2310may includes an odd or prime number of non-axisymmetric features, which extend to an outer diameter whose dimensions are typically similar to the dimensions of the outer diameter of the diaphragm. For example, the vertices2332are formed by a triangular feature radiating from a central aperture2310, producing a “6 pointed star” shaped aperture. Additionally, the acoustic lens2300may further include a number of axisymmetric “vent” apertures located near an outer diameter of the acoustic lens2300whose dimensions are typically similar to the dimensions of the outer diameter of the diaphragm. The number of axisymmetric vent apertures may be an odd number or a prime number. The combined surface area of the “vent” apertures is typically less than or equal to the surface area of the aperture2310. The acoustic lens2300may include features to mate to a frame of a speaker or speaker assembly, while providing clearance for the moving diaphragm assembly. The acoustic lens2300is typically composed of plastic or metal, but could be composed of other suitable materials.

Acoustic lens2300has similar performance of the acoustic lens2200, however, the acoustic lens2300provides further suppression and/or distribution of the cavity resonances. The improved cavity resonance performance provides a higher and smoother sound pressure level at high frequencies. Additionally, the directivity typically changes more smoothly with frequency and may in some examples be higher in some frequency ranges

FIG. 24depicts a top and cross-sectional view of an acoustic lens. As depicted, an acoustic lens2400may include a form similar to the acoustic lens2200, where like numbers and features correspond. The acoustic lens2400further includes vent apertures2422,2424,2426,2428,2430similar to the vent apertures of the acoustic lens2200. However, the vent apertures of the acoustic lens2400may be non-axial symmetric. Furthermore, the vent apertures of the acoustic lens2400may be wedge shaped or triangular shaped. Accordingly, the vent apertures of the acoustic lens2400may be a polygonal shaped aperture having odd numbers of sides or a prime number of sides. Furthermore, the sides of vent apertures of the acoustic lens2400may further include curved features.

The surface area of the aperture2410is typically at least 15% of the surface area of the acoustic lens2400. Additionally, the non-axisymmetric “vent” apertures may be located on an outer diameter, whose dimensions are typically similar to the dimensions of the outer diameter of the diaphragm of the speaker over which the acoustic lens2400is positioned.

In some examples, the combined surface area of the “vent” apertures is typically less than or equal to the surface area of a centrally located aperture similar to the aperture2410. The acoustic lens2400may include features to mate to a frame of a speaker assembly or speaker while providing clearance for the moving diaphragm assembly. The acoustic lens2400may be composed of plastic, metal, or other suitable materials.

InFIG. 25, a top and a cross-sectional view of acoustic lens2500. InFIG. 25, the acoustic lens2500may include a form similar to the acoustic lens2300, where like numbers and features correspond. However, unlike the acoustic lens2300, the acoustic lens2500is depicted as having an aperture2410that is substantially shaped as a five pointed etoile or five pointed star. In addition, unlike the vent opening of acoustic lens2300, the vent openings of the acoustic lens2500may be configured as an estoile or star shape. WhileFIG. 25depicts the vent apertures as beings substantially shaped as a five pointed star, some examples of the acoustic lens2500may include a vent aperture with a different number of radiating point than the aperture2510.

FIG. 26depicts a top and cross-sectional view of phase plug2600. InFIG. 26, the phase plug2600may be configured to mount over the sound producing surface of a speaker (not shown). The phase plug2600includes a first surface2602and a second surface2604. The first surface2602and the second surface2604form a union to create an exterior edge or lip2606. The exterior lip or edge2606may be configured to rest upon a mounting feature of the speaker. The first surface2602and the second surface2604unite to form an interior lip or edge2608. The interior lip2608delineates an aperture2610, where the interior lip2608delineates a cross-sectional area of the aperture2610.

As a non-limiting example, the aperture2610includes an axisymmetric opening in or near the central location of the first surface2602and the second surface2604. The exterior or edge2008may have a thickness of between 0.5-2.5 mm thick. However, unlike the acoustic lens2000, the phase plug2600plug fills in more of the cavity created when the phase plug2600is mounted to a speaker, which is not shown. Upon mounting the phase plug2600on the speaker, a cavity is formed between the second surface2604and the diaphragm (not shown) of the speaker.

The surface area of the cross-section of the aperture2610may be 15% or more of the surface area of the top of the plug. The phase plug2600may include features to mate to a frame of a speaker. The phase plug2600may be configured to allow a clearance between the speaker and the second surface2610. The clearance allows for non-interference between the phase plug2600and the diaphragm assembly. Accordingly, the clearance permits the movement of the diaphragm assembly without coming into contact with the phase plug2600. The phase plug2600may be composed of plastic, metal, or other suitable materials.

Performance of the phase plug2600is similar to the phase plug2000. However, phase plug2600decreases the volume of the cavity between the diaphragm and the plug. The decreased cavity volume increases the Helmholtz resonance frequency. The decreased cavity volume may increases the Helmholtz resonance frequency range while decreasing the Helmholtz resonance sound pressure level.

The increase in the length of the aperture2610(“port”) causes a decrease in the Helmholtz resonance frequency, a decrease in the frequency range, and an increase in sound pressure level. The net result depends on the relative contributions of volume decrease and “port length” increase of the aperture2610. The port length increase of aperture2610may also cause peaks and dips due to port resonances, which may be in addition to cavity resonances. The directivity of the phase plug2600is similar to the phase plug2000, except at highest frequencies. The use of the phase plug2600may increase the sound pressure “insertion loss” and distortion.

FIG. 27depicts a top view and a corresponding cross-sectional view of a phase plug2700. The phase plug2700may be configured to mount over the sound producing surface of a speaker (not shown). The phase plug2700includes a first surface2702and a second surface2704. The first surface2702and the second surface2704unite to form an exterior edge or lip2706. The exterior lip or edge2706may be configured to rest upon a mounting feature of the speaker. The first surface2702and second surface also form a union to form an interior lip or edge2708. The interior lip2708delineates an aperture2710, where the interior lip2708delineates a cross-sectional area of the aperture2710.

The interior lip2708may be configured to include edges of various geometric to shapes. Illustratively, the interior lip2708may be configured to resemble an etoile, an estoile, or star-like shape having a plurality of vertices2712and2714. Illustratively, some vertices, similar to the vertex2714, may project into the aperture2710. Other vertices, similar to the vertex2714, may project outwardly from a center of the aperture2710. Although depicted as a star having five radiating points, other examples may include an etoile, estoile, or star shaped aperture having an odd number of radiating points. Still other examples may include an aperture as an irregular polygon, an estoile, or an etoile.

Some examples of the phase plug2700may include a tapered or sloped portion to conform the second surface2704to interface with a speaker assembly (not shown). At the exterior edge2706, phase plug2700may have a thickness of between about 0.5-2.5 mm at the exterior edge.

The aperture2710may be non-axisymmetric about the center of the body of the phase plug2700. The cross-sectional area delineated by the interior lip2708of the aperture2710is typically 15% or more of the surface area of the phase plug2700. In some examples, the aperture2710may include an odd—typically prime number, of non-axisymmetric features. The non-axisymmetric features may extend to an outer diameter whose dimensions are typically similar to the dimensions of the outer diameter of the diaphragm of a speaker mounted proximate to the second surface2704(not shown).

For example, the phase plug2700includes five triangular features radiating from a central aperture. The five triangular features may be joined to form a “five pointed star” shaped aperture. The phase plug2700may include features to mate to a frame and be further configured to provide a clearance to accommodate movement of a diaphragm assembly of the speaker. Similar to the acoustic lens2100, the phase plug2700may be composed of plastic or metal, but could be composed of other suitable materials.

As a non-limiting example, the aperture2710includes an axisymmetric opening in or near the central location of the first surface2702and the second surface2704. The exterior or edge2708may have a thickness of between 0.5-2.5 mm thick. However, unlike the acoustic lens2000, the phase plug2700plug fills in more of the cavity created when the phase plug2700is mounted to a speaker, which is not shown. Upon mounting the phase plug2700on the speaker, a cavity is formed between the second surface2704and a diaphragm of the speaker (not shown).

The surface area of the cross-section of the aperture2710may be 15% or more of the surface area of the top of the plug. The phase plug2700may include features to mate to a frame of a speaker. The phase plug2700may be configured to allow a clearance between the speaker and the second surface2710. The clearance allows for non-interference between the phase plug2700and the diaphragm assembly. Accordingly, the clearance permits the movement of the diaphragm assembly without coming into contact with the phase plug2700. The phase plug2700may be composed of plastic, metal, or other suitable materials.

The phase plug2700performs similar to the phase plug2600. However, the phase plug2700better suppresses and/or distributes the port and cavity resonances. As a result, examples of the phase plug2700typically provide a higher and smoother sound pressure level at high frequencies. Additionally, the typical directivity of the phase plug2700changes more smoothly with frequency, but may be higher in some frequency ranges.

FIG. 28depicts a top view and a cross-sectional view of the phase plug2800. The phase plug2800may be configured to mount over the sound producing surface of a speaker (not shown). The phase plug2800includes a first surface2802and a second surface2804. The first surface2802and the second surface2804form a union to create an exterior edge or lip2806. The exterior lip or edge2806may be configured to rest upon a mounting feature of the speaker. The first surface2802and second surface also form a union to form an interior lip or edge2808. The interior lip2808delineates an aperture2810.

As shown in the cross-sectional view ofFIG. 28, a port feature2832of the phase plug2800may bulge inwardly to constrict the aperture2810. Accordingly, the edge of the port feature2842delineates an effective cross-sectional area of the aperture2010. Although not depicted inFIG. 28, the port feature2832may include asymmetric features or otherwise be non-symmetric. In addition, inFIG. 28, the second surface2804of the phase plug2800may include an interior curved feature2840that forms a portion of the interior edge2808.

As a non-limiting example, the aperture2810includes an axisymmetric opening in or near a central location of the first surface2802and the second surface2804. The exterior lip or edge2808may have a thickness of between 0.5-2.5 mm thick.

The aperture2810of the phase plug2800may include an axisymmetric feature located approximately in the center of first surface2802. Similar to the phase plug2700, the phase plug2800fills the cavity between the diaphragm of the speaker (not shown) and the second surface2804. One or both ends of the aperture may be contoured. The surface area of the aperture2810is typically 15% or more of the surface area of the top of the plug. The plug has features to mate to a frame while providing clearance for the moving diaphragm assembly of a speaker. The phase plug2800may be composed of plastic, metal or other suitable materials.

The phase plug2800performs similar to the phase plug2700, except that the frequency response of the phase plug2800may be smoother. In addition, the phase plug2800may have a significantly reduced sound pressure “insertion loss.” In addition, the phase plug2800may have a significant reduction in distortion.

FIG. 29depicts a top and cross-sectional view of a phase plug2900. The phase plug2900may be configured to mount over the sound producing surface of a speaker (not shown). The phase plug2900includes a first surface2902and a second surface2904. The first surface2902and the second surface2904form a union to create an exterior edge or lip2906. The exterior lip or edge2906may be configured to rest upon a mounting feature of the speaker. The first surface2902and second surface also form a union to form an interior lip or edge2908. The interior lip2908delineates an aperture2910, and where the interior lip2908delineates a cross-sectional area of aperture2910.

Similar to the phase plug2600, the phase plug2900may include the aperture2910configured as an axisymmetric opening in or near the central location of the first surface2902and the second surface2904. The exterior or edge2908may have a thickness of between 0.5-2.5 mm thick. However, unlike the phase plug2600, the phase plug2900plug fills in more of the cavity created when the phase plug2900is mounted to a speaker, which is not shown. Upon mounting the phase plug2900on the speaker, a cavity is formed between second surface2904and a diaphragm (not shown) of the speaker.

The surface area of the cross-sectional area of the aperture2910may be 15% or more of the surface area of the top of the phase plug2900. The phase plug2900may include features to mate to a frame of the speaker. The phase plug2900may be configured to allow a clearance between the speaker and the second surface2910. The clearance allows for non-interference between the phase plug2900and the diaphragm assembly of the speaker. Accordingly, the clearance permits the movement of the diaphragm assembly without coming into contact with the phase plug2900. The phase plug2900may be composed of plastic or metal. Phase plug2900may also be composed of other suitable materials.

Performance of the phase plug2900is similar to the phase plug2600. However, the phase plug2900decreases the volume of the cavity between the diaphragm and the plug. The decreased cavity volume increases the Helmholtz resonance frequency. The decreased cavity volume may increase the Helmholtz resonance frequency range while decreasing the is Helmholtz resonance sound pressure level.

Similar to the phase plug2200, inFIG. 22, the phase plug2900further includes additional “vent” apertures. InFIG. 29, like numbered elements of phase plug2200are similar to like numbered elements of the phase plug2900.

InFIG. 29, the first surface2902and second surface2904may unite to form additional interior lips2912,2914,2916,2918, and2920, where each of the vent lips2912,2914,2916,2918, and2820delineate respective vent apertures2922,2924,2926,2928, and2930.

InFIG. 29, each respective aperture is located about the axisymmetric opening2910. In some examples, the vent apertures2922,2924,2926,2928, and2930may be distributed proportionally. In other examples, the vent apertures2922,2924,2926,2928, and2930may be distributed approximately the same distance from the central axis of the aperture2910. However, in other examples, the vent apertures2922,2924,2926,2928, and2930may be distributed at varying distances from the center of aperture2910. AlthoughFIG. 29depicts five “vent” apertures located about the exterior diameter, near the outer edge2906of the phase plug2900, other examples may include vent apertures distributed asymmetrically about the aperture2910. In addition, other examples may include non-axisymmetric “vent” apertures or a combination of different types of vent apertures similar to the vent apertures depicted in the acoustic lens2400and2500. The combination of the vent apertures2922,2924,2926,2928, and2930and the aperture2910provide an increase in total aperture area.

Examples of the phase plug2900may have a similar performance as phase plug2600. However, the phase plug2900may exhibit a higher Helmholtz resonance frequency. In addition, compared to the phase plug2600, the phase plug2900may have a wider Helmholtz resonance frequency range and a lower Helmholtz resonance sound pressure level. The higher Helmholtz resonance frequency, wider frequency range, and lower sound pressure level are due to the increase total aperture area. The directivity of the phase plug2900is typically higher from the Helmholtz resonance frequency to the frequency with a corresponding wavelength approximately equal to pi times the effective radius of the central aperture. Above this frequency, the sound pressure level and directivity are typically essentially unchanged. In addition, the phase plug2900typically has a reduced sound pressure “insertion loss” and distortion.

FIG. 30depicts a phase plug3000. Similar to the phase plug100, the phase plug3000may include a first member3001. The first member3001may include a first surface3002and a second surface3004. The first surface3002and the second surface3004of first member3001may unite to from a first exterior edge3006and a first interior edge3008. The first interior edge3008may delineate a first aperture3010.

The phase plug3000may further include a second member3011that may include a third surface3013and a fourth surface3015. The third surface3013and the fourth surface3015may united to form a second exterior edge3017and a second interior edge3019. The interior edge3019may delineate a second aperture3021.

Similar to acoustic lens100, phase plug3000may be formed by joining the first member3001and the second member3011. InFIG. 3000, similar to phase plug100, the second surface3004and third surface3013are located in opposition to form at least one aperture3023between the first member3001and the second member3011.

In some examples of the phase plug3000, the apertures3010,3021, and3023may join together to form a passage through the phase plug3000.

The phase plug3000may include an axisymmetric passage through the center of phase plug3000. Similar to the phase plug100, the phase plug3000fills the cavity between the diaphragm of a speaker and the fourth surface3019. The surface areas of the first aperture3010and second aperture3021are typically 15% or more of the surface area of the first surface3002of the phase plug3000. The total surface area of aperture(s)3023is typically less than 15% of the surface area of the first surface3002of the phase plug3000.

In some examples, the phase plug3000may include an odd or prime number of cross-sectional area slots that extend from the side of the aperture/passage3010to the bottom surface of the phase plug3000. The combined surface area of the slots is typically less than or equal to the surface area of the central aperture3010. The phase plug3000may include features to mate to a frame of a speaker while providing clearance for a moving diaphragm assembly of the speaker. The plug is typically composed of plastic or metal, but could be composed of other suitable materials.

The performance of the phase plug3000is similar to the phase plug2600. However, the phase plug3000may have a lower Helmholtz resonance frequency, a wider frequency range, and a lower sound pressure level increase. The sound pressure level and directivity are typically lower above the Helmholtz resonance frequency. In comparison to the phase plug2600, the sound pressure “insertion loss” and distortion of the phase plug3000are typically reduced.

FIG. 31depicts a phase plug3100, which is similar to the phase plug100. The phase plug3100includes a first member3160, a second member3162, and a third member3164. The first member3160may be joined to the second member3162by support members similar to the support members of phase plug100. The second member3162may be joined to the third member3164by support members similar to the support members of the phase plug100.

InFIG. 31, a third member3164includes a protuberance similar to the protuberance152of the phase plug100. The third member3164may further include a rounded or beveled surface3166configured to be positioned over a dustcap of a speaker (not shown).

The first member3160and the second member3162form at least one aperture3170to permit sound energy to pass through phase plug3100into a central orifice3110. The second member3162and the third member3164form at least one aperture3172configured to permit sound energy to pass through the phase plug3100into the central orifice3110.

Acoustic lens3200is depicted in various profiles and orientations inFIGS. 32,33, and34. In addition, inFIG. 35, a perspective view of an assembly including acoustic lens3200is further shown. InFIG. 24, acoustic lens3200is similar, although not the same as, acoustic lens2400.

InFIG. 32, a perspective view of acoustic lens3200is shown with an orientation including the top3202of acoustic lens3200. As such, the bottom3204of acoustic lens3200is depicted in the later describedFIG. 34.

Acoustic lens3200may include an orifice or an aperture3208located approximately or near the center of member3210. Member3210includes a first side3212and a second side3214, where the second side is visible in the bottom view ofFIG. 34. The first side3212unites with the second side3214to form an exterior edge3216. In addition, member3210is conformed to produce a rim3206. InFIG. 32, rim3206may include a uniform distance from the center of the orifice3208. However, depending upon the speaker to which the acoustic lens3200is to be mated, the rim3206may be adapted to have other forms including but not limited to an elliptical form.

The first side3212may also unite with the second side3214to form the interior lip3216, which defines the outer boundary of orifice3208. The interior lip3216may include a beveled edge, a tapered edge, a straight edge, a rounded edge, or a combination thereof.

Member3210may include an exterior edge3216that in combination with rim3206forms a mounting feature3215. InFIG. 33, the mounting feature3213may include a foot feature or mounting surface3316.

InFIG. 32, member3210may further include a supplementary aperture3230, which are similar to the apertures2422,2424,2426,2428, and2430, as inFIG. 24.

The first surface3212and the second surface3214may further unite to form supplementary apertures3230,3232,3234,3236, and3238. As an example, the first surface3212and second3214may unite to form lip3244. Lip3244may define the outer triangular-like perimeter of supplementary aperture3232.

As another example, the triangular aperture3230may include a vertex3240oriented towards aperture3208. Vertex3240may be rounded or curved. The triangular form of supplementary aperture3230may also include a base or first side3240oriented to be substantially parallel to the exterior edge3216. As another example, the lip3244of supplementary aperture3236may further include a second side3246and a third side3448. The second side3246and the third side3248may connect the base or first side3242to the vertex3240.

Member3210may include a central portion3250. The central portion3250may encompass the aperture3208in the proximate center3209of member3210. The central portion3250may further include one or more of the supplementary apertures3230,3232,3234,3236, and3248. The central portion3250may be slightly elevated above an outer portion or ring3254.

InFIG. 32, with reference to supplementary aperture3234, central portion3250may include a setback portion3254. The setback portion3254separates each of the supplementary apertures3230,3232,3234,3236, and3248from the centrally located aperture3208.

As an additional example, inFIGS. 32 and 33, the first surface3212may unite with the second surface3214to form lip3260of supplemental aperture3230. The lip3260may define boundary of the supplementary aperture3230. The supplemental boundary may include a base or first side3264, a second side3266and a third side3268. The second side3266and third side3268may unite to form a vertex3262. The second side3266and third side3268may also unite with first side or base3264to form a triangular shape. The first side3264, the second side3266, and the third side3268may each have a different length. Alternatively, the second side3266and the third side3268may have identical lengths.

FIGS. 33 and 34depict a top view and cross-sectional view of acoustic lens3200. The dashed-line A depicts the location of the cross-sectional view of acoustic lens3200. The dashed-lines B and D show the outer perimeters of the orifice3208as it aligns with the cross-sectional view. In the cross-sectional view ofFIG. 33, the element3256, that separates orifice3208and supplementary aperture3234may be seen. In addition, dashed-line C, when taken with dashed-line A, shows the approximate center position3209of the aperture3208, as well and the approximate location of the center location in the cross-sectional view.

In addition,FIGS. 33 and 34depict the second side3214and the mounting feature3215. The mounting feature3213includes a foot feature3260, upon which the acoustic lens3200may rest upon a speaker assembly3212. The mounting feature3213and foot feature3316are depicted as a ring-like feature to offset the second surface3214from the mounting surface.

FIG. 35depicts a perspective view of an assembly3500. Assembly3500may include an acoustic lens3200coupled to speaker3510. The speaker3510may include a motor pot assembly3512and a diaphragm assembly3514. In addition, the speaker3510may include a basket/bracket assembly3530to facilitate mounting of the speaker assembly3500. Bracket3530may further include one or more mounting holes3532, through which various fasteners may be passed to secure the speaker assembly3500in a final installation.

The speaker3510and the acoustic lens3200are joined by a substantially airtight seal3520. The substantially airtight seal may be created by the use of various adhesives to glue the foot3316of acoustic lens3200to bracket3530. Alternatively, clip-like features or other fasteners (not shown) may be used in combination with a gasket (not shown) inserted between bracket3530and acoustic lens3200to create the substantially airtight seal3530. The gasket may include ferromagnetic or thermally conductive material.

A magnet structure of the loudspeaker3510may include a plurality of magnets (not shown), contained within a motor pot assembly3512. The acoustic lens3200may be composed of ferromagnetic material. Accordingly, magnetic flux generated by the plurality of magnets may be collected by the acoustic lens, which acts at least in part as a magnetic flux collector.

FIG. 54depicts an example of a cross-sectional view of the assembly ofFIG. 35. In inFIG. 54, return flux lines5410passing through an example ferromagnetic acoustic lens3200. The distance that the magnetic flux lines may travel are reduced by collection on the top surface3202and bottom surface3204. Alternatively or in addition, flux lines may be conducted through member3210of acoustic lens3200. The ferromagnetic acoustic lens, in combination with the bracket3530and speaker frame3532, may provide a direct, low reluctance, and controlled path for magnetic energy to be channeled into an air gap included in the loudspeaker3510.

The acoustic lens3200may be constructed of a ferromagnetic material. Alternatively, the acoustic lens3200may be coated or painted with ferromagnetic material. The acoustic lens3200may be coupled with the magnet housing of the loudspeaker.

InFIG. 54, the loudspeaker3510may include multiple magnets disposed (not shown) in a predetermined configuration in the magnet housing3516, which houses one or more magnets5402. The ferromagnetic acoustic lens3200may attract and focus magnetic energy back into the magnet housing and into the air gap. The ferromagnetic acoustic lens3200may be further coupled with a magnetic flux collector5402integrated into the magnet housing3516, into a frame of the loudspeaker3532, flux collector5402, and adjoining the magnet housing3516, or a combination of the magnet housing and the frame3532.

InFIG. 54, magnetic flux lines5410are substantially contained within the speaker apparatus3500. At least some portion of the magnetic flux lines5410generated by magnet5402are collected by the magnetically conductive ac ferromagnetic acoustic lens3200and returned to the magnet housing3516via a combination of the frame of the loudspeaker3532and/or magnetic flux collector5402. In some examples, the magnetic flux collector5410and frame3532may be combined into a single piece.

The loudspeaker3510may be manufactured by separately constructing a first assembly and a second assembly. The first assembly and the second assembly may each be a portion of the loudspeaker3510. The first assembly may include a magnet housing3516and a magnetic flux collector5410. The second assembly may include a support frame and a cone of the loudspeaker. The first assembly and second assembly may be detachably coupled to form the loudspeaker. Accordingly, the first assembly or second assembly may be replaceable parts. Thus, either the first assembly or the second assembly may be replaced with a different first assembly or second assembly by detaching the first and second assemblies, replacing one of the first assembly or second assembly, and reusing the other of the first assembly or the second assembly to form a loudspeaker.

FIGS. 36,37, and38depict a acoustic lens3600, which is similar to the acoustic lenses inFIGS. 21,25, and27. Acoustic lens3600includes a top3602. In addition, acoustic lens3600includes a bottom3604and a plurality of orifices or apertures located in and around a center portion. Member3610includes a first surface3612and second surface3614. First surface3612and second surface3614unite to form an internal lip3618. Internal lip3618substantially defines the outline of an orifice3608. Orifice3608is located approximately in the center of member3610.

The first surface3612and the second surface3614may also unite to form a plurality of lips3620,3622,3624,3626, and3628. Each of the lips3620,3622,3624,3626, and3628correspond to secondary apertures, orifices or vents,3630,3632,3634,3636, and3638, respectively.

FIG. 36, in combination withFIG. 37, further depicts a segment of the internal lip3618that corresponds to protrusion3640, which defines an internal vertex3740of protrusion3640. The protrusion3640may further include at least some portion of supplementary aperture3630. Another segment of the interior lip3618further defines an edge of protrusion3642. The interior lip3618may include a plurality of local paiapsii and local apaspsii relative to the center of the aperture3608. As an example, the interior lip3618may include an interior vertex or local apoapsi of3742.

Protrusion3642includes at least some portion of supplementary aperture3632. Another segment of internal lip3618may define an edge of protrusion3644. The edge of protrusion3644may also include an interior vertex3744. The protrusion3644may further include some portion of aperture3634. Another segment of interior lip3618may define an edge of protrusion3646, which includes an interior vertex3746. Protrusion3646may further include supplementary aperture3636. Another segment of internal lip3618defines an edge of protrusion3638, which includes interior vertex3748. Protrusion3648may further include at least a portion of supplementary aperture3638.

InFIGS. 37 and 38, the dashed-line A and dashed-line D cross at an approximate center position3709of orifice3608.FIG. 37further depicts a cross-sectional view of acoustic lens3600. The orifice3608may be centrally located within member3610. In addition, the interior lip3630, in combination with the protrusions3640,3642,3644,3646, and3648, may form a star-like, estoile, or etoile shaped orifice3608.

InFIGS. 37 and 38, the interior edge of protrusion3640meets the interior edge of protrusion3642to form an outer vertex or local paiapsii3660of orifice3608. The interior edge of protrusion3642may also meet the interior edge of protrusion3644to form the outer vertex or local paiapsii3662of orifice3608. The interior edge of protrusion3644may also meet the interior edge of protrusion3646to form the outer vertex or local paiapsii3664of orifice3608. The interior edge of protrusion3646may meet the interior edge of protrusion3648to form the outer vertex or local paiapsii3666of orifice3608. The interior edge of protrusion3648may meet the interior edge of protrusion3640to form the outer vertex or local paiapsii3668.

The distance between the approximate center3609of orifice3608to any one of the outer vertices or local paiapsii3660,3662,3664,3666, and3668, may be adjusted to further refine the overall directivity or frequency response of the acoustic lens3600. The distance between the approximate center3609of aperture3608to any one of the outer vertices or local paiapsii3660,3662,3664,3666, and3668may be uniform or identical. Alternatively, the distance of at least one of the outer vertices or local paiapsii3660,3662,3664,3666, and3668may be different from the distance to another of the outer vertices3660,3662,3664,3666, and3668.

Similarly, the distance between the approximate center of the orifice3608to the interior vertices or apoapsiis3740,3742,3744,3746, and3748, may also be adjusted to further refine the overall directivity or frequency response of the acoustic lens3600. In addition, the relative distances to each individual interior vertex or outer vertex may be independently adjusted to minimize respective nulls in the frequency response of the acoustic lens. In doing so, an overall frequency response within a desired band of frequencies may be optimized.

In addition, the shape, size, and relative position of the supplementary orifice3630,3632,3634,3636, and3638may be adjusted to optimize insertion loss and distortion related to the movement of air through the acoustic lens. Although not depicted here, as described in other examples, the overall shape and surface area of each of the supplementary apertures may be the same or different and may have independent sizes depending upon the desired overall frequency response, directivity, insertion loss, and distortion.

InFIG. 38, the bottom view3604and side view of acoustic lens3600. As also shown inFIG. 37, the side view depicts a ridge3652that may rise to a central portion3650of member3610. The central portion3650may include stiffing portions3656, as inFIG. 36.

FIG. 39depicts a perspective view of an assembly3900. Assembly3900may include an acoustic lens3600coupled to speaker3910. The speaker390may include a motor pot assembly3912and a diaphragm assembly3914. In addition, the speaker3910may include a basket/bracket assembly3930to facilitate mounting of the speaker assembly3900. Bracket0530may further include one or more mounting holes3532, through which various fasteners may be passed to secure the speaker assembly3500in a final installation.

The speaker3510and the acoustic lens3200are joined by a substantially airtight seal3520. The substantially airtight seal may be created by the use of various adhesives to glue the foot3316of acoustic lens3200to bracket3530. Alternatively, clip-like features or other fasteners (not shown) may be used in combination with a gasket (not shown) inserted between bracket3530and acoustic lens3200to create the substantially airtight seal3530. The gasket may include ferromagnetic or thermally conductive material.

FIGS. 40-43depict acoustic lens4000.FIGS. 44 and 45depict the installation of acoustic lens4000with a speaker in a speaker assembly4400.

InFIG. 40, acoustic lens4000includes a top side4002. The acoustic lens4000may include a centrally located aperture4008. The centrally located aperture4008includes a plurality of small perforations to permit air to pass through the acoustic lens4000. In FIG>42, the acoustic lens4000further includes a bottom side4004. The acoustic lens4000further includes an outer perimeter defined by an exterior edge4006.

The acoustic lens4000includes member4010. InFIG. 42, member4010includes a first surface4012and a second surface4014. The first surface4012unites with the second surface4014to form the exterior perimeter edge4006. In addition, the exterior edge4006is conformed to include a mounting feature4013. Mounting feature4013includes a standoff portion as well as a foot portion4016. The foot portion4016is conformed to mate with a speaker assembly, as will be discussed relative toFIGS. 40 and 45.

FIG. 40further depicts that the perforated aperture4008includes a centrally located dome4020. Dome4020includes a perforated portion and an imperforated portion4022located at the apex of the dome4020. The imperforated portion4022is solid and formed to provide a glue point for a scrim.

Member4010further includes a conical section4024. The conical section4024connects with the dome4020to form a union or fold4034in the first surface4012. The contouring of the member4010may provide for structural stiffness. Member4010further includes an axisymmetric solid portion that surrounds both the conical section4024and the dome4020. The conical section4024unites with the solid portion4030to form a union4034. In addition, the conical section4024may be divided into a imperforated or solid portion4032and a perforated portion4036. The outer border of the perforated portion4040may be arranged in various geometric shapes, as described relative to other phase plugs and acoustic lenses.

FIG. 41depicts a top view and cross-sectional view of acoustic lens4000. Dashed-line B and dashed lined D indicate a position relative to dashed-line A of the concentric fold created by the union of dome4020and conic section4024. The apex of the dome is located at the intersection of dashed-line A and dashed-line C.

In the case where the acoustic lens4000is made of a metal, such as steel, the combination of the concentric folds with the dome feature4020provides mechanical strength to stiffen the acoustic lens4000. The mechanical stiffening may be adjusted to reduce the vibration of the perforated aperture4008during sound reproduction. In the cross-sectional view ofFIG. 41, the mounting feature4013may include a concentric foot4016. The mounting feature4013may include an edge4015. The edge4015may define the outer perimeter or exterior edge4006.

FIG. 42depicts the bottom side4004of the acoustic lens4200. Similar toFIG. 41, the dashed-lines B and D border the outer perimeters of dome4020. In addition, similar toFIG. 41, the dashed-line C passes through the center point of acoustic lens4000. However, the apex4022of dome4020may be located either above, below, or near the first plane depending upon the desired stiffness of the perforated aperture4020. Likewise, the relative location of the fold4110may be adjusted with respect to the second plane to provide appropriate stiffening of the effective aperture4008

FIG. 44depicts speaker assembly4400. Speaker assembly4400may include acoustic lens4000and speaker4410. InFIG. 45, speaker4410may include a speaker pot4412, which holds a magnet4510. In addition, the speaker4410may further include an exterior shell4014and a mounting ring4416. In the assembly4400, the acoustic lens4000is united with the speaker4410to form a substantially air-tight seal at4420. As previously described, the air-tight seal4420may be obtained by the use of an adhesive or a glue. Alternatively, a gasket (not shown) may be inserted between the speaker4410and acoustic lens4000. Additional mounting hardware may be used to hold acoustic lens4000in place relative to speaker4410to create the substantially air-tight seal4420.

FIG. 45depicts a cross-sectional view of the assembly shown inFIG. 44. Speaker4410includes a magnet4510, which resides in motor pot4412. Speaker4410further includes a dustcap4520coupled to diaphragm4522. Diaphragm4522couples to surround4512. Dome4020is downwardly convex relative to the dustcap4520and speaker4410. The angle of the conic section4024may be adjusted to create a desired volume between the speaker and the bottom4004of acoustic lens4000. In addition, the curvature of dome4020in the angle of the conic section4024may be adjusted to position the fold4110relative to the dustcap4520and diaphragm4522.

FIG. 46depicts a top view of acoustic lens4600. The acoustic lens4600is similar to the acoustic lens3600, inFIGS. 36-39, and the acoustic lens4000, inFIGS. 40-45.

The acoustic lens4600includes a plurality of perforations or holes that may be centrally located to form an effective aperture4608similar to the acoustic lens4000. Similar to the acoustic lens3600, the perforations are arranged to form an effective aperture4008that may include a star-like shape, an etoile shape, or an estoile shape. Similar to the acoustic lens4000, the acoustic lens4600may include a dome shaped portion4609and conical portion4610.

In addition, the acoustic lens4600may include additional perforations or holes arranged to form supplementary apertures, auxiliary apertures or vents4630,4632,4634,4636, and4638.

The supplementary apertures, the auxiliary apertures, or vents4630,4632,4634,4636, and4638may be arranged to define a border, where the border further defines a shape. The border of each of the supplementary apertures, the auxiliary apertures, or vents4630,4632,4634,4636, and4638may define a triangular shape, a star-like shape, an etoile shape, an estoile shape, a circular shape, and/or an elliptical shape. As an example, supplemental aperture4630may include a star-like shape. Auxiliary apertures4632,4634,4636, and4638may include a circular shape.

The perforations may have an identical form and cross-sectional area. Alternatively, the perforations may have different surface areas. As an example, the perforations that form supplemental aperture4630vary in cross-sectional area.

FIG. 47depicts a top view of an acoustic lens4700, which is similar to the acoustic lens3600, inFIGS. 36-39, and the acoustic lens4600, inFIG. 46. The acoustic lens4700may include an aperture4708that may include a star-like shape, an etoile-like shape, or an estoile-like shape. The acoustic lens4700includes an interior lip that defines the aperture4608. The interior lip includes a plurality of outer vertices or local paiapsii4760,4762,4764,4766, and4768and interior vertices or local apoapsii4740,4742,4744,4746, and4748.

Relative to an approximate center of the aperture4708, the distance to each of the interior vertices or local paiapsii4740,4742,4744,4746, and4748may be different. For example, dashed lines4782indicates the distance between the center of aperture4708and local paiapsi4768. Also, relative to an approximate center of the aperture4708, the distance to each of the interior vertices or local apoapsiis4740,4742,4744,4746, and4748may be different. For example, dashed lines4780indicates the distance between the center of aperture4708and interior vertex or local apoapsii4766.

InFIGS. 1-46, the phase plugs and acoustic lenses may include a primary aperture. For example, inFIG. 1, the aperture140may be a primary aperture having a primary aperture size. InFIGS. 20-31, acoustic lenses2000,2100,2200,2300,2400,2500,2600,2700,2800,2900,3000, and3100may include respective primary apertures2010,2110,2210,2310,2410,2510,2610,2710,2810,2910,3010and3110. InFIGS. 32-46, phase plugs, phase plugs, and acoustic lenses3200,3600,4000,4600, and4700may include primary apertures or effective apertures3208,3608,4008,4608, and4708.

The primary aperture size of each of the phase plugs or acoustic lenses may be chosen to meet a given Directivity Index (DI) target within a desired frequency range as follows:

c=speed of sound in air (m/s)=343,

J1=Bessel Function of Order 1.

As a first example, an aperture radius of a=0.023 m, which is a diameter of about 47 mm, and which corresponds to an aperture surface area of about 1735 mm2. Accordingly, at a frequency of 4000 Hz, the expected directivity index (DI) is approximately 2 dB.FIG. 48depicts the performance of an acoustic lens optimized for use up to around 4000 Hz.

Line4810is the on-axis response of the speaker with an acoustic lens. Line4812is the power response of the speaker with an acoustic lens. The difference between the line4810and line4812is the directivity index4830. Line4820is the on-axis response of the speaker without an acoustic lens. Line4822is the power response of the speaker without an acoustic lens.

The difference between the line4820and line4822is the directivity index4832. As shown inFIG. 48, the speaker assembly with the acoustic lens has lower directivity through 10,000 Hz. In addition, comparing lines4810and4812to lines4820and4812at 2000 Hz, the power output of the speaker with the acoustic lens is greater than the speaker without an acoustic lens.

The Helmholtz resonance frequency and “Q” (height of the peak) of each of the phase plugs or acoustic lenses may be chosen to provide gain in a desired frequency range as follows:

where

c=speed of sound in air (m/s)=343,

S=surface area of aperture (m2),

V=volume of air between the speaker diaphragm and the phase plug (m3),

m=mass of air in aperture (kg),

ρ0=density of air (kg/m3)=1.21,

Rr=acoustical radiation resistance (Ns/m), and

For a phase plug or acoustic lens having an aperture surface area (S) of 1735 mm2, a volume (V) of 40000 m3, an effective aperture thickness (L′) of 40 mm, and a mechanical resistance (Rm) of 0.27 Ns/m, the Helmholtz resonance frequency (f0) is 1800 Hz and the Helmholtz resonance quality factor (Q) is 6 dB. As shown in the data ofFIG. 48, this relationship may be confirmed by comparing the PWL curve4812at the top ofFIG. 48to the PWL curve4822at the top ofFIG. 48. The PWL curve4812has a peak centered at 1800 Hz with a height of 6 dB.

The acoustic lowpass behavior and/or “cavity resonances” (Tπ) of the assembly of a speaker and a phase plug or acoustic lens may be estimated. For a speaker having a surface area of the diaphragm (Sd), measured in square meters (m2), a phase plug or acoustic lens having an aperture surface area (S), also measured in square meters (m2), and an effective aperture thickness (L′),

Accordingly, the insertion loss (IL), measured in dB, for a volume displacement of the diaphragm Vd, measured in cubic meters (m3), of the phase plug or acoustic lens in union with the speaker may be empirically estimated as

As an example, for an aperture surface area (S) of 570 mm2and a volume displacement of the diaphragm (Vd) of 3877 mm3, the estimated insertion loss (IL) is 0.5 dB. Confirmation of the estimated IL is shown by the data inFIG. 48. The SPL transfer function curve4810shows a flat, constant, low frequency portion, which defines the IL, is about 0.5 dB. Other example acoustic lenses have an insertion loss less than 1 dB.

Distortion and insertion loss related effects may be reduced by adjusting the overall surface area of the apertures of the acoustic lens. For example, for an acoustic lens having an insertion loss of the acoustic lens is less than 1 dB, a plurality of supplemental apertures may be added. Each of the supplemental apertures may include a surface area “Ss”.

Alternatively, the average cross-sectional surface area of all the supplemental apertures may be “Ss,” where at least one of the supplemental apertures has a different dimension or cross-sectional surface area. The average cross-sectional surface area or the total additional cross-sectional area of the supplemental apertures may be adjusted to maintain a desired ratio of volume displacement of the speaker, “Vd”, to the combination of all the surface areas “Ss” and S. For example, in some cases, a compression ratio of less than 10 may be desirable.

The acoustic lens may improve directivity of the loud speaker. In addition, the acoustic lenses may minimize the negative impact on SPL/PWL frequency response, insertion loss, and distortion. While in some frequency ranges the SPL/PWL may be reduced, another benefit is that the acoustic lenses described herein may increase SPL/PWL in other frequency regions. Another benefit of the acoustic lenses described herein is acoustic lowpass filtering behavior. These improvements may be obtained at essentially any audio frequency. The improvements typically span a frequency range of at least one octave to two or more octaves.

InFIG. 48, the output of the speaker with the phase plug or acoustic lens, may increase overall sound power output. The increased overall sound power output may be indicated by comparison of the power output of the same speaker without the phase plug or acoustic lens4822to the power output of the same speaker with a phase plug or acoustic lens4812over the operating bandwidth (200-4000 Hz). The directivity index is lower on the speaker with the phase plug or acoustic lens than on the speaker without the phase plug or acoustic lens over its operating bandwidth. Accordingly, the speaker assembly with a phase plug or an acoustic lens simultaneously may have increased sound power output over a wider listening angle that the same speaker assembly without the phase plug or acoustic lens.

InFIG. 49, insertion loss4910of an acoustic lens in a speaker assembly is less than 0.5 dB below 1000 Hz. In addition, the insertion loss remains lower longer than the relatively high insertion loss4920of a phase plug over the frequency range between 315 Hz and 1000 Hz.

InFIGS. 50A and 50B, polar response data shows directivity improvement of an example of the phase plug, the acoustic lens, or the assembly, inFIGS. 1-47. InFIG. 50A, the plots show a polar response of a speaker, at different off-axis angles, with a phase plug or acoustic lens. InFIG. 50B, the plots show a polar response of a speaker at different off-axis angles, without a phase plug or acoustic lens. The speaker response without the speaker5150,5151,5052,5053,5054,5055,5056,5057, and5058correspond to the off-axis response at 0 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, and 80 degrees off-axis, respectively.

InFIG. 50A, a grouping of on-axis normalized polar response characteristics 5012 are grouped at 0 db. The groupings of off-axis normalized polarized responses at5010shows that the characteristics are grouped within 10 db. In contrast, inFIG. 50B, the groupings of off-axis normalized responses5020is spread, less tightly grouped, at the 80 degree off-axis position. Comparing the response characteristics of a speaker with and without the acoustic lens may be characterized by the tightness of the grouping of the polar response at various off-axis angles from the on-axis position of the loudspeaker.

As another example of improved directivity performance, in51A, the off-axis sound pressure level (SPL) data from a speaker without an acoustic lens has relatively tight groupings5110,5112, and5114, of response curves. In contrast, in FIG. B, the off-axis sound pressure level data has groupings5120and5122. The relatively tight groupings5110,5112, and5114, correspond to improved directivity. In contrast, inFIG. 51B, the grouping o5110and5112of the SLP for each off-axis position diverges substantially and non-uniformly.

InFIG. 52, the THD data5220represents relatively high distortion effects of an example of a phase plug, where the relatively high distortion add around 4.5% of additional TEM to the performance of the system. In contrast, the THD data5220represents the THD of a speaker assembly with an acoustic lens, as described herein, where the THD is relatively low and adds no more than 1.6% of additional THD.

FIG. 53depicts data representative of a sound pressure level (SPL), a power watt level (PWL), and a directivity index (DI) for a speaker without an acoustic lens). InFIG. 53, sound pressure level (SPL)5310, power watt level (PWL)5312, and the directivity index (DI)5330correspond to the performance of an assembly having a speaker and an acoustic lens. In contrast, sound pressure level (SPL)5320, power watt level (PWL)5322, and the directivity index (DI)5332correspond to the performance of the same speaker without an acoustic lens.

InFIG. 53, the on-axis response5320of the speaker without an acoustic lens is contrasted with power response5322of the speaker without an acoustic lens. The difference between the on-axis response5320and power response5322is the directivity index5232. As shown inFIG. 48, the speaker assembly with the acoustic lens has lower directivity through 20,000 Hz. In addition, comparing the on-axis response5310and power response5312of the speaker with the acoustic lens to the on-axis response5320and power response5322of the speaker without the acoustic lenses, at around 1800 Hz, the power output of the speaker with the acoustic lens is greater than the speaker without an acoustic lens.

The phase plug or acoustic lens may be formed from a material that includes a ferromagnetic material or has ferromagnetic properties. Some phase plugs or acoustic lenses may include a perforated surface. Alternatively, phase plugs or acoustic lenses may include a ferromagnetic mesh over the apertures of the phase plugs or acoustic lenses. In other examples, the phase plug or acoustic lens may be magnetically coupled back to the speaker in order to improve magnetic flux collection. In addition to reducing stray magnetic flux, the improved magnetic flux collection, as described above, may increase the efficiency of the speaker. In addition, the material that forms the phase plug may be selected to enhance heat dissipation, provide stray magnetic flux shielding, and magnetic flux collection, as described above.

While various examples of the invention have been described, it will be apparent to those of ordinary skill in the art that many more examples and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.