PATENT DOCUMENT

Publication Number: US-10063962-B2
Application Number: US-201615197240-A
Country: US
Kind Code: B2

Title: Vented acoustic enclosures and related systems

Abstract:
An enclosure for a speaker transducer can have a front housing member and a rear housing member. Some enclosures position the speaker transducer between the front housing member and the rear housing member, and spaced apart from the rear housing member to define a rear chamber positioned between the speaker transducer and the rear housing member. The rear housing member can define a longitudinal axis. A first waveguide member and a second waveguide member can be longitudinally spaced apart from each other to define an acoustic waveguide therebetween oriented transversely relative to the longitudinal axis. A port can acoustically couple the acoustic waveguide with the rear chamber. A cross-sectional area of the waveguide can expand radially outward of the port. And, the acoustic waveguide can extend circumferentially around the longitudinal axis more than 90-degrees. Some embodiments include a speaker transducer and are suitable as a headphone.

Claims:
What is currently claimed: 
     
       1. An enclosure for a speaker transducer, the enclosure comprising:
 a rear housing member defining a concave chamber region having a longitudinal axis extending therethrough; 
 a front wall; 
 a rear wall longitudinally spaced apart from the front wall to define a channel positioned between the front wall and the rear wall and oriented transversely relative to the longitudinal axis, wherein the channel extends at least 90-degrees circumferentially around the longitudinal axis, and 
 a port extending between the chamber region and the channel, wherein the port contracts from the chamber region such that a cross-sectional area of the port is substantially less than a cross-sectional area of the chamber region adjacent to the port, and the channel expands radially outward of the port such that the cross-sectional area of the port is less than a cross-sectional area of the channel adjacent to the port. 
 
     
     
       2. The enclosure according to  claim 1 , wherein the cross-sectional area of the channel outward of the port varies substantially linearly with radial position relative to the longitudinal axis. 
     
     
       3. The enclosure according to  claim 2 , wherein a gap-distance between the front wall and the rear wall is substantially constant radially outward of the port. 
     
     
       4. The enclosure according to  claim 1 , wherein the channel extends from a proximal end positioned adjacent the port to a terminal end positioned adjacent a vent between the channel and an environment. 
     
     
       5. The enclosure according to  claim 4 , wherein the cross-sectional area of the channel expands from a position radially outward of the port to a position adjacent the vent. 
     
     
       6. The enclosure according to  claim 4 , wherein the channel is arranged to attenuate acoustic noise entering the terminal end through the vent from the environment. 
     
     
       7. The enclosure according to  claim 1 , wherein the port and the channel are together configured as an acoustic low-pass filter having a cut-off frequency less than about 1,500 Hz. 
     
     
       8. The enclosure according to  claim 1 , wherein each of the rear waveguide member and the rear housing member constitutes a respective portion of a unitary construct. 
     
     
       9. The enclosure according to  claim 8 , wherein the rear housing member defines the port. 
     
     
       10. The enclosure according to  claim 1 , further comprising a front housing member, wherein each of the rear waveguide member and the front housing member constitutes a respective portion of a unitary construct. 
     
     
       11. The enclosure according to  claim 10 , wherein the front housing member defines the port. 
     
     
       12. The enclosure according to  claim 1 , further comprising an acoustic damper overlying the port. 
     
     
       13. The enclosure according to  claim 12 , wherein the acoustic damper comprises an acoustic mesh. 
     
     
       14. A headphone comprising:
 a speaker transducer; 
 a front housing member and a rear housing member, wherein the speaker transducer is positioned between the front housing member and the rear housing member, and spaced apart from the rear housing member to define a rear chamber positioned between the speaker transducer and the rear housing member, wherein the rear housing member defines a longitudinal axis; and 
 a first waveguide member and a second waveguide member spaced apart from each other to define an acoustic waveguide oriented transversely relative to the longitudinal axis; 
 a port acoustically coupling the acoustic waveguide with the rear chamber, wherein a cross-sectional area of the acoustic waveguide expands radially outward of the port relative to the longitudinal axis, wherein the acoustic waveguide extends circumferentially more than 90-degrees around the longitudinal axis, 
 wherein a cross-sectional area of the port is substantially less than a cross-sectional area of the rear chamber at a position adjacent to the port and substantially less than the cross-sectional area of the acoustic waveguide at a position adjacent to the port, such that the port contracts from the rear chamber and expands to the acoustic waveguide. 
 
     
     
       15. The headphone according to  claim 14 , wherein the waveguide comprises an annular waveguide. 
     
     
       16. The headphone according to  claim 14 , wherein the speaker transducer defines a longitudinal axis, wherein the longitudinal axis of the speaker transducer is collinear with the longitudinal axis of the rear housing member. 
     
     
       17. The headphone according to  claim 14 , wherein the speaker transducer defines a longitudinal axis, wherein the longitudinal axis of the speaker transducer is offset from the longitudinal axis of the rear housing member. 
     
     
       18. The headphone according to  claim 14 , wherein each of the first waveguide member and the rear housing member constitutes a respective portion of a unitary construct. 
     
     
       19. The headphone according to  claim 18 , wherein the rear housing member defines the port. 
     
     
       20. The headphone according to  claim 14 , wherein each of the first waveguide member and the front housing member constitutes a respective portion of a unitary construct. 
     
     
       21. The headphone according to  claim 20 , wherein the front housing member defines the port. 
     
     
       22. The headphone according to  claim 14 , wherein the port comprises a first port, wherein the acoustic waveguide and the rear chamber are acoustically coupled together through at least one other port circumferentially spaced apart from the first port relative to the longitudinal axis defined by the rear housing member.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of and priority to U.S. Patent Application No. 62/187,107, filed Jun. 30, 2015, the contents of which patent application are hereby incorporated by reference as if recited in full herein for all purposes. 
    
    
     BACKGROUND 
     This application, and the innovations and related subject matter disclosed herein, (collectively referred to as the “disclosure”) generally concern acoustic enclosures, and more particularly but not exclusively, enclosures suitable for headphones, with several vented enclosures for headphones being but particular examples incorporating disclosed innovations. Some disclosed enclosures define a waveguide for enhancing a frequency response, while also being configured to provide a thin enclosure. Some disclosed waveguides are further configured to passively attenuate environmental noise without substantially interfering with passive noise attenuation for headphones. 
     Audio headphones are worn on or over a user&#39;s ears. Audio headsets can have a headband for supporting a headphone in relation to a user&#39;s head. Often, such headsets include a pair of headphones, and the headband supports and separates the headphones from each other. Each headphone, in turn, can have one or more respective speaker transducers, sometimes referred to as “speakers” or “loudspeakers positioned within a housing. Generally speaking, the housing can define an acoustic enclosure for the speaker, providing the headphone with selected acoustic characteristics (e.g., a selected response at various audible frequencies, a degree of acceptable harmonic distortion, etc.). Headphones can also have ear pads, or cushions. Typically, ear cushions are provided to make wearing the headset comfortable, and to passively attenuate ambient noise. 
     As noted, ear pads for headphones or ear cushions for earphones can improve comfort for a user. Circumaural headphone ear pads and occluding earphone ear cushions, and to a smaller extent supraaural headphone ear pads and non-occluding earphone ear cushions, can also attenuate sound waves emitted by sources other than a corresponding headphone or earphone speaker transducer and can thus improve a user&#39;s listening experience in relation to sound emitted by the transducer. Such attenuation is sometimes referred to in the art as “passive” noise cancellation or attenuation. 
     In general, “passive” noise attenuation mechanically insulates a wearer&#39;s ear in relation to environmental sources of sound (generally referred to as “noise”). Although passive noise attenuation can improve a user&#39;s listening experience, it can be ineffective or less effective than desired for some frequency bands (e.g., below about 500 Hz). 
     A circumaural headphone, commonly referred to in the art as an “over-the-ear headphone,” has an ear pad configured to surround a user&#39;s outer ear and presses directly against the user&#39;s head at a position outwardly of the ear. By contrast, a supraaural headphone, commonly referred to in the art as an “on-ear headphone”, has an ear pad that rests on the wearer&#39;s outer ear. 
     Circumaural and supraaural headphones are contrasted with earphones that have small speaker enclosures typically worn in the user&#39;s outer ear, e.g., at an entrance to the wearer&#39;s ear canal. Some earphones do not have ear cushions. Other earphones have a cushioning member configured to enhance user comfort and/or to modify sound quality. Some cushioning members for earphones occlude a wearer&#39;s ear canal, and other cushioning members do not occlude the ear canal. 
     An enclosure for a speaker can define a first chamber and an opposed second chamber positioned opposite the first chamber relative to the speaker. Each chamber can be sealed or vented. Although a sealed chamber is not necessarily hermetically sealed, a sealed chamber inhibits or substantially prevents a flow of an ambient fluid, for example, air, across a boundary of the chamber as a diaphragm of the speaker vibrates to-and-fro emitting sound. By contrast, a vented chamber permits a flow of the ambient fluid across a boundary of the chamber. A given speaker combined with a vented chamber can provide different acoustic characteristics as compared to the same speaker combined with a sealed chamber. 
     For example, overall sound quality of a speaker combined with a sealed chamber, particularly in context of an enclosure for an earphone or headphone, is sometimes described as providing improved bass response, yet with a smaller soundstage and less fidelity compared to a vented (or “open”) enclosure. Such fidelity loss can arise, in part, from sympathetic acoustic and mechanical resonances within the chamber. 
     Nonetheless, conventional open enclosures do not lend themselves to passive acoustic attenuation, as external noise can “leak” through conventional vented chambers. As well, audio playback can “leak” through conventional open enclosures and disturb others near the listener. 
     An acoustic transmission line, or waveguide, can improve low-end frequency response of a vented enclosure. However, acoustic waveguides desirably provide a continuously expanding cross-sectional area (or nozzle). Conventional waveguides, therefore, have been large and bulky, and generally unsuitable for use in applications where small or otherwise diminutive enclosures are required or desired, such as in headphone or earphone applications, or in applications where aesthetic considerations are important. 
     Therefore, a need exists for improved loudspeaker enclosures. For example, enclosures providing strong bass response combined with high fidelity over desired audible frequencies are needed. A similar need exists for small or diminutive enclosures that allow users to enjoy accurate (e.g. low-distortion) reproduction of sound over extended low-frequencies. As well, a need remains for such enclosures that provide substantial passive noise attenuation. In addition, a need remains for such enclosures that are compatible with thin headphones and/or earphones. 
     SUMMARY 
     The innovations disclosed herein overcome many problems in the prior art and address one or more of the aforementioned or other needs. In some respects, innovations disclosed herein are directed to acoustic enclosures, and more particularly, but not exclusively, to headphone enclosure arrangements. In other respects, innovations disclosed herein pertain to vented speaker enclosures, with vented enclosures for headphones being but particular examples of acoustic enclosures incorporating innovative principles disclosed herein. 
     Enclosures for a speaker transducer are disclosed. A rear housing member can define a concave chamber region having a longitudinal axis extending therethrough. The enclosure can have a front wall and a rear wall longitudinally spaced apart from the front wall. A channel can be defined by the gap between the front wall and the rear wall. At least a segment of the channel can be oriented transversely relative to the longitudinal axis. A port can extend between the chamber region and the channel. The channel extends at least 90-degrees circumferentially around the longitudinal axis, and wherein a cross-sectional area of the channel continuously expands radially outward of the port. 
     Headphones are also disclosed. A headphone can have a speaker transducer, a front housing member and a rear housing member. The speaker transducer can be positioned between the front housing member and the rear housing member, and spaced apart from the rear housing member to define a rear chamber positioned between the speaker transducer and the rear housing member. The rear housing member can define a longitudinal axis. A first waveguide member and a second waveguide member can be spaced apart from each other to define an acoustic waveguide oriented transversely relative to the longitudinal axis. The waveguide can be acoustically coupled with the rear chamber through a port. A cross-sectional area of the acoustic waveguide can expand radially outward of the port relative to the longitudinal axis. The acoustic waveguide can also extend circumferentially more than 90-degrees around the longitudinal axis. 
     The foregoing and other features and advantages will become more apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Unless specified otherwise, the accompanying drawings illustrate aspects of the innovative subject matter described herein. Referring to the drawings, wherein like numerals refer to like parts throughout the several views and this specification, several embodiments of presently disclosed principles are illustrated by way of example, and not by way of limitation, wherein: 
         FIG. 1A  shows a side view of a loudspeaker enclosure having a longitudinally extending waveguide; 
         FIG. 1B  shows a plot of cross-sectional area in relation to longitudinal position for the waveguide shown in  FIG. 1A ; 
         FIG. 1C  shows a side view of another loudspeaker enclosure having a longitudinally extending waveguide; 
         FIG. 1D  shows a plot of cross-sectional area in relation to longitudinal position for the waveguide shown in  FIG. 1C ; 
         FIG. 2  schematically illustrates a side view of a cross-section of a headphone enclosure having a radially extending waveguide; 
         FIG. 3  shows an exploded view of another headphone enclosure having a radially extending waveguide; 
         FIG. 4  shows a side view of a cross-section of the headphone enclosure shown in  FIG. 3 ; 
         FIG. 5  shows additional detail of the cross-section shown in  FIG. 4 ; 
         FIG. 6  shows the rear housing member shown in  FIG. 4 ; 
         FIG. 7  shows the rear housing member shown in  FIGS. 4 and 6  with acoustic mesh extending over several acoustic port exhaust apertures; 
         FIG. 8  shows the rear housing member shown in  FIG. 7  with a gasket installed; 
         FIG. 9  shows a partial sectional view of the rear housing member shown in  FIGS. 4 and 6  with acoustic mesh over several acoustic port inlet apertures; 
         FIG. 10  shows a partial sectional view of the rear housing member and acoustic mesh arrangement shown in  FIG. 9  with a gasket installed, as in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     The following describes various innovative principles related to acoustic enclosures by way of reference to specific examples of headphone enclosures, and more particularly but not exclusively, to vented headphone enclosures. Nonetheless, one or more of the disclosed principles can be incorporated in various other enclosures, or systems, to achieve any of a variety of corresponding system characteristics. Acoustic enclosures and systems described in relation to particular configurations, applications, or uses, are merely examples of acoustic enclosures and systems incorporating one or more of the innovative principles disclosed herein and are used to illustrate one or more aspects of the innovative principles. 
     Thus, enclosures and systems having attributes that are different from those specific examples discussed herein can embody one or more of the innovative principles, and can be used in applications not described herein in detail, for example, acoustic enclosures for earphones, home-stereo speakers, speaker bars, hearing aids, automobile speakers, etc. Accordingly, alternative embodiments of disclosed innovations also fall within the scope of this disclosure. 
     Overview 
       FIG. 1A  schematically illustrates a portion of an enclosure  10  for a speaker transducer. The enclosure defines a rear chamber  30  positioned “behind” a transducer  40  (i.e., relative to a front environment  60  adjacent a diaphragm of the transducer). A rear wall  32  of the chamber  30  defines an acoustic port  33  opening to a waveguide  70  extending longitudinally away from the rear chamber. The waveguide  70  opens to a rear environment  80 . 
     A cross-sectional area of the illustrated waveguide  70  changes in proportion to a longitudinal distance, X, away from the wall  32  separating the rear chamber  30  from the waveguide. The acoustic port acoustically couples the rear chamber  30  to the acoustic waveguide  70 , or horn, and can provide improved fidelity (e.g., in part through reducing resonance) compared to similarly sized enclosures having a sealed rear chamber. To achieve such improved fidelity, the cross-sectional area of the waveguide  70  continually and monotonically expands in correspondence with the longitudinal distance, X, from the acoustic port  33  in the rear wall  32 , as indicated in the plot in  FIG. 1B . The enclosure  10 , chamber  30 , and waveguide  70  can be axisymmetric (e.g., about a longitudinally extending axis parallel to the X-axis shown in  FIG. 1B ), but need not be. 
     The waveguide acts like a tuning tube when the mesh does not occur until after the waveguide. The rear chamber  30  can be “tuned” by adjusting a cross-sectional area of the port  32 . An acoustic damper, or mesh, can adjust the Q factor of that tuning by damping the air flow through the port. 
     The Q factor is a dimensionless parameter that compares the exponential time constant τ for decay of an oscillating physical system&#39;s amplitude to its oscillation period. It compares a frequency at which a given system oscillates to a rate at which it dissipates its energy. Physically speaking, Q is 2π times a ratio of the total energy stored divided by the energy lost in a single cycle or equivalently a ratio of the stored energy to the energy dissipated over one radian of oscillation. 
     A theoretically perfect transmission line, or waveguide, would absorb all frequencies entering the line from the rear chamber, but is not practically attainable, as it would have to be infinitely long. In physically implementable waveguides, usually upper bass frequencies are loaded (e.g., fully absorbed), and the low-end bass frequencies are allowed to freely radiate from enclosure. Waveguides thus effectively function like a low pass filter, providing a sort of physically implemented acoustic crossover. This energy combines with the output of the bass unit, extending the enclosure&#39;s low-frequency response. 
     Once the enclosure is tuned, the waveguides guide the output to the outside environment. Critically damping the port with an acoustic mesh can provide a smooth frequency response to the enclosure. 
     Structure shown in  FIG. 1C  is similar, but not identical, to structure shown in  FIG. 1A . Such similar structure shares the same reference numeral as that shown in  FIG. 1A , but the difference is indicated by a prime (i.e., a “′”) or a double prime (i.e., a “″”). The rear wall  32 ′ in  FIG. 1C  defines a first acoustic port  33 ′. Longitudinally aft of the first acoustic port, the enclosure defines a throat having an expanded cross-sectional area, and a second rear wall  32 ″ defines a second acoustic port  33 ″. The nozzle portion of the waveguide  70  expands longitudinally aft of the second port  33 ″ in an identical fashion as the waveguide  70  shown in  FIG. 1A . 
     However, the enclosure shown in  FIG. 1C  yields inferior fidelity compared to the enclosure shown in  FIG. 1A  because the enclosure in  FIG. 1C  does not provide a monotonically increasing cross-sectional area for sound waves to expand. As  FIG. 1D  shows, the cross-sectional area expands longitudinally immediately aft of the first acoustic port  32 ′, remains constant over the length of the throat, contracts at the second acoustic port  33 ″ and then expands monotonically aft of the second acoustic port. Such expansion followed by contraction can impair acoustic performance. 
     Each waveguide  70  defines a major axis corresponding to a general direction over which the cross-sectional area expands. In  FIGS. 1A and 1C , the major axis defined by the waveguide  70  is coextensive with a longitudinal axis defined by the rear chamber  30 . Consequently, the waveguide  70  shown in  FIGS. 1A and 1C  extends longitudinally away from the rear chamber  30  and the transducer  40 , yielding a longitudinally deep enclosure  10  generally ill-suited for applications requiring a shallow enclosure. 
     Enclosures Having a Radial Waveguide 
     In contrast to the enclosures shown in  FIGS. 1A and 1C ,  FIGS. 2 through 10  illustrate relatively shallow enclosures  110 ,  210  having waveguides extending generally radially outward and circumferentially of a longitudinal axis defined by each respective enclosure. For example, the waveguides  170 ,  270  shown in  FIGS. 2 and 4  include a segment having a major axis oriented transversely, and in some instances orthogonally, relative to the longitudinal axis  102  of the enclosure. Despite having a constant or nearly constant channel height (e.g., spacing between walls), the acoustic cross-sectional area of the waveguides  170 ,  270  expands in correspondence with increasing radial dimension relative to the longitudinal axis  102 . Such a “flat,” radial expansion keeps the waveguide and enclosure longitudinally thin while obtaining acoustic benefit of a continuously expanding cross-sectional area, as with the waveguide  70  shown in  FIG. 1A . 
     Despite being substantially “thinner”, the enclosures  110 ,  210  still provide desirable acoustic performance. In some instances, the rear chamber  230 ,  330  can have a volume of about 15 cm 3  (cubic centimeters, or “cc”). Chambers having different volumes are contemplated. In some instances, a rear chamber  130 ,  230  can have a volume between about 10 cc and about 20 cc, such as between about 14 cc and about 18 cc, with about 18.4 cc being but one particular example. 
     An acoustic port  124 ,  224  can have a cross-sectional area of about 150 mm 2  (square millimeters, or sq. mm.). Acoustic ports can have different areas, as well, such as between about 100 sq. mm and about 200 sq. mm., such as between about 130 sq. mm and about 170 sq. mm, with about 150 sq. mm. being but one particular example. 
       FIG. 2  shows a first embodiment of a enclosure  110  for a speaker transducer  140 , and  FIGS. 3 through 10  show a second embodiment of a loudspeaker enclosure  210  for a speaker transducer  240 . Both enclosures  110 ,  210  are suitable for headphone applications. The enclosures  110 ,  210  share several common features, including radially extending waveguides  170 ,  270 . For succinctness, several other common aspects of the enclosures  110 ,  210  are described in this section. Additional aspects of each enclosure are described separately, below. 
     The enclosures  110 ,  210  can be described using a cylindrical coordinate system  101  ( FIG. 2 ). In each enclosure, a longitudinal axis  102  extends generally centrally through a center of the enclosure  110 ,  210 . A radial dimension, r, extends orthogonally from the longitudinal axis, and an azimuthal dimension, θ, extends circumferentially around the longitudinal axis  102 . Although a cylindrical coordinate system is convenient for describing the generally cylindrical headphone embodiment depicted in  FIGS. 2 through 10 , other headphone configurations are possible (e.g., a headphone having an elliptical cross-section taken orthogonally to the longitudinal axis  102 ). Thus, although enclosures having a circular cross-section (sectioned orthogonally relative to the longitudinal axis  102 ) are described in detail below, the principles described below are equally suited for non-circular cross-sections. Accordingly, each reference to a shape using a term connoting a circle can be substituted with reference to another shape corresponding to a given headphone&#39;s actual cross-sectional shape without departing from the principles disclosed herein (e.g., thin waveguides that expand outwardly). 
     Each enclosure  110 ,  210  has a rear housing member  190 ,  210   a  defining a concave chamber region  130 ,  230  having a longitudinal axis  102  extending therethrough. Each enclosure  110 ,  210  also has a front wall  112 ,  212  and a rear wall  123 ,  223  longitudinally spaced apart from each other to define an outwardly expanding (relative to the longitudinal axis  102 ) channel  170 ,  270  positioned therebetween. As indicated in the cross-sectional views of  FIGS. 2 and 4 , a major axis defined by at least a segment of the channel  170 ,  270  formed between the front wall and the rear wall is oriented transversely relative to the longitudinal axis  102 . 
     In both enclosures,  110 ,  210 , a corresponding port  124 ,  224  extends between the chamber region  130 ,  230  and the channel  170 ,  270  forming the outwardly expanding (or radially extending) waveguide. In addition to extending radially, each channel  170 ,  270  extends circumferentially around the longitudinal axis by at least 90-degrees. For example, a projection of the illustrated waveguides  170 ,  270  on an r-O plane (shown in the cylindrical coordinate system  101  in  FIG. 2 ) can define an annulus, or at least a sector thereof extending at least 90 degrees circumferentially around the axis  102 . Waveguides of the type disclosed herein extend between at least 90 degrees and 360 degrees, such as between about 90 degrees and about 180 degrees, with particular waveguides extending circumferentially by between about 100 degrees and about 140 degrees, with about 120 degrees being but one particular example. 
     In each case, a cross-sectional area of the channel  170 ,  270  continuously expands in correspondence with increasing radial distance outward of the port  124 ,  224 . For example, where the channel  170 ,  270  has a constant a gap-distance between the front wall  112 ,  212  and the rear wall  123 ,  223  at positions radially outward of the port  124 ,  224 , the cross-sectional area of the channel outward of the port generally varies linearly with radial position relative to the longitudinal axis  102 . 
     More particularly, the cross-sectional area at a given radial position, r, can be computed according to a product between the radial position, r, and an average longitudinal gap dimension between the front wall  112 ,  212  and the rear wall  123 ,  223  at the selected radial position. Accordingly, the radially extending waveguide  170 ,  270  can provide a suitable expansion of cross-sectional area to permit enhanced response at selected frequencies while maintaining a relatively thin (e.g., along the longitudinal direction  102 ) waveguide, and hence a relatively thin headphone  100 . 
     However, cross-sectional area variation can deviate from a linear variation. For example, some enclosures have one or more standoffs, or support pillars, (not shown) extending between the front wall  112 ,  212  and the rear wall  123 ,  223  to inhibit vibration-induced contact between the front wall and the rear wall. Such standoffs can reduce the acoustic cross-sectional area by a nominal measure at a given radial distance from the axis  102 . Effects arising from such area reductions can be mitigated, as by adjusting the pillars&#39; location and/or by increasing a longitudinal gap between the front wall and the rear wall in regions adjacent the pillars. 
     The channel  170 ,  270  extends from a proximal (e.g., a radially inner) end positioned adjacent the acoustic port  124 ,  224  to a terminal (e.g., a radially outer) end positioned adjacent a vent  128 ,  228  between the channel  170 ,  270  and an environment  180 ,  280 . Thus, the cross-sectional area of the channel can continuously expand from a position radially outward of the port to a position adjacent the vent. 
     As with the port  33  shown in  FIG. 1A , a cross-sectional area of the port  124 ,  224  is substantially less than a cross-sectional area of the chamber region  130 ,  230  adjacent the port and substantially less than the cross-sectional area of the channel  170 ,  270  at a position adjacent the port. Stated differently, the acoustic port  124 ,  224  represents a sudden contraction and a sudden expansion from the rear chamber region. 
     The gap spacing and rate of outward expansion of the waveguide, as well as the degree of damping of apertures  152 ,  124  in the grille region  151  and adjacent the waveguide  170 , respectively, can be selected in accordance with their respective effects on overall headphone tuning. For example, the gap spacing between the front waveguide member  112 ,  212  and the rear waveguide member  123 ,  223  can vary radially in a selected manner to achieve a desired waveguide tuning. 
     As well, an acoustic damper, e.g., an acoustic mesh, can overlie the port  124 ,  224  to tune a frequency response of the enclosure  110 ,  210 . In some working embodiments, the port and the channel can operate as an acoustic low-pass filter having a cut-off frequency less than about 1,500 Hz, such as, for example, between about 1,250 Hz and about 1450 Hz. 
     And, a direction of the major axis of the channel  170 ,  270  can vary from being directly outward (e.g., orthogonal to the axis  102 ) to being within several (e.g., about 10) degrees of parallel to the axis  102 , as the arrow  273   d  in  FIG. 5  indicates. Thus, as the channel  170 ,  270  extends radially outward of the port  124 ,  224 , the major axis of the channel can follow a circuitous outward path, as indicated by the arrows  273   a, b, c  and  d . Configurations of the front walls  112 ,  212  and the rear walls  123 ,  223  providing specific examples of such circuitous paths are described more fully below in connection with the specific enclosure embodiments shown in  FIG. 2  and in  FIGS. 3-10 . Headphones having a circuitous waveguide  170 ,  270  can attenuate acoustic noise entering the terminal end of the channel from the environment, e.g., through the vent  128 ,  228 , enhancing passive attenuation of ambient noise while providing extended low-frequency response. 
     A generally annular cushion member  160 ,  260  extends longitudinally inward of the housing, defining an open interior region  161 ,  261  configured to receive a wearer&#39;s outer ear when the headphone  100  is donned. The cushion member  160 ,  260  can be formed of any suitable material arranged in any suitable configuration to provide a wearer comfort. Some arrangements permit the cushion to sealingly engage a wearer&#39;s head to provide a measure of passive noise attenuation. 
     An annular cushion retainer  111  ( FIG. 2 , similar structure is shown but unlabeled in  FIG. 4 ) can matingly engage with a relatively distal waveguide member  112  to retain an inner most edge  162  of the cushion member  160  therebetween. 
     Enclosure Example 1 
     Additional details of the headphone  100  shown in  FIG. 2  will now be described. 
     The enclosure  110  shown in  FIG. 2  has a front housing member  121 . The rear waveguide member  123  extends outwardly from the front housing member  121 . Stated differently, the front housing member  121  and the rear waveguide member  123  shown in  FIG. 2  constitute respective portions of a unitary construct. In  FIG. 2 , the front housing member  121  defines the acoustic port  124 . 
     As shown in  FIG. 2 , an enclosure  110  for a headphone  100  can have a first chamber  120  and an opposed second chamber  130  relative to a speaker transducer  140 . The first chamber  120  can be positioned between the transducer  140  and a grille portion  151  positioned adjacent an open region  161  occupied by a wearer&#39;s ear (not shown) when the headphone  100  is donned. The grille portion  151  can define a plurality of apertures  152 , and a suitable acoustic mesh (not shown) can overlie the grille portion so as to provide a selected degree of acoustic damping across the grille. 
     The opposed second chamber  130  can be positioned on a side opposite the first chamber  120  relative to the transducer  140 , such that the transducer  140  lies, at least generally, between the first chamber  120  and the second chamber  130 . The first chamber  120  is sometimes referred to in the art as a “front chamber” and the second chamber  130  is sometimes referred to in the art as a “rear chamber.” An annular boundary of the second chamber  130 , in this instance a housing wall  131 , can encircle the transducer  140  and lie adjacent to, and radially outward of, the first chamber  120 . Such an arrangement of the chambers  120 ,  130  can provide suitable acoustic performance while maintaining an acceptably thin enclosure  110 . 
     One or more walls  131 ,  190  can define corresponding boundaries of the rear chamber  130 . A plurality of apertures, or ports,  124  can extend through a boundary of the rear chamber  130  to acoustically couple the rear chamber  130  with a channel  170  extending outwardly of the ports relative to the transducer  140 . As  FIG. 2  shows, the apertures can extend through a wall defining a boundary of the rear chamber  130 . A suitable acoustic mesh can damp each port  124  to facilitate tuning of the enclosure  110 . 
     As also shown in  FIG. 2 , disclosed waveguides (e.g., channel  170 ) can extend in a circuitous path, generally radially outward of the transducer  140 . A circuitous waveguide  170  can provide a desired degree of passive attenuation of non-directional, external noise. 
     Front housing member  121  defines a generally circular grille region  151  corresponding to a generally circular headphone transducer  140 . The grille region  151  is spaced apart from a diaphragm member  141  of the transducer  140  to define a front chamber  120  therebetween. The grille region  151  defines a plurality of apertures  152 , and an acoustic mesh (not shown) can overlie the grille region to selectively damp (e.g., to tune) the front chamber  120 . In some instances, the grille region  151  defines a domed region positioned proximally of the transducer and its diaphragm  141 . 
     Radially outward of the grille region  151  and the transducer  140 , the housing member  121  defines an aperture  122  extending between a rear chamber  130  and the open interior region  161  defined by the annular cushion member  160 . The aperture  122  can have any suitable arrangement. For example, the aperture can comprise a plurality of circular openings, a plurality of arcuate slots, or a plurality of any other suitable opening. The aperture  122  opening between the rear chamber  130  and the open interior region  161  can be covered with an acoustic mesh for tuning the rear chamber. In some embodiments, a sufficient land area positioned outward of the aperture can provide a region of attachment (e.g., for adhesive attachment) for the mesh. 
     In  FIG. 2 , an innermost portion  113  of the annular waveguide member  112  extends radially outward substantially in an r-Θ plane to define a bearing surface for urging against a corresponding inner-most portion of the cushion member  160 . Radially outward of the bearing surface, the illustrated waveguide member  112  defines a convex surface  114  (relative to a user&#39;s head, or a proximal position along the longitudinal axis  102 ). Stated differently, outwardly of the radially inner-most portion  113 , the waveguide member  112  extends longitudinally proximally of the radially inner-most portion  113  before gently and continuously curving outward and extending radially outward to a proximal-most longitudinal position. At the proximal-most longitudinal position, the convex surface  114  extends radially outward in an r-Θ plane and curves to extend distally relative to the longitudinal axis  102 , while still flaring radially outward to an outermost edge  115 . 
     A thin foam or other suitable vibration-damping material can be positioned between the convex surface  114  of the waveguide member  112  and a corresponding concave surface of the cushion retainer  111  to inhibit rattling between the closely spaced members  111 ,  112 . The outermost edge  115  of the illustrated waveguide member  112  is positioned proximally along the longitudinal axis  102  relative to an outermost edge  116  of the cushion retainer  111 . 
     In  FIG. 2 , the housing member  121  extends in a longitudinally distal direction outward of the axis  102  before curving to extend predominantly radially outward to define a generally annular rear waveguide member  123  having a complementary shape compared to the front waveguide member  112 . In the predominantly radially outward portion of the housing member  121 , an aperture  124  can open between the rear chamber  130  and an open waveguide region  170  defined by the gap between the longitudinally proximal (or front) waveguide member  112  and the longitudinally distal (or rear) waveguide member  123  of the housing member  121 . The aperture  124  is configured as an acoustic port. 
     Like the front waveguide member  112  and the cushion retainer  111 , the rear waveguide member  123  can define a convex region  125  positioned radially inward of an outermost, predominantly longitudinally extending wall portion  126 . An outermost lip  127  of the housing member  121  can be positioned opposite a corresponding land region  116  of the cushion retainer  111  relative to an outermost edge  162  of the cushion member  160 . The outermost edge  162  of the cushion member  160  can be retained between the outermost lip  127  of the housing member  121  and the land region  116  of the cushion retainer  111 . 
     The front housing member  121  can define an aperture  128  positioned radially inward of the outermost lip  127 . The aperture, or vent,  128  can open between a radially outer-most portion of the waveguide  170  and an environment  180  external of the headphone  100 . 
     The speaker transducer  140  can be positioned longitudinally distally of the front housing member  121  and co-centrically aligned with the circular grille portion  151  thereof. A generally dome-shaped rear housing member  190  can enclose a rear region  142  of the transducer  140  to define the rear chamber  130 . As shown in  FIG. 2 , an annular flange  191  portion of the dome-shaped housing member  190  can urge against or matingly engage with a corresponding annular flange of the housing member  121 , enclosing the rear chamber  130 . 
     The headphone  100  can also include an outermost housing member  195  overlying the generally dome shaped member  190 , defining a suitable enclosure for, for example, digital signal processing components, microphones, processors, and other headphone components. 
     Enclosure Example 2 
     Additional details of the headphone  100  shown in  FIGS. 3 through 10  will now be described. 
     The enclosure  210  defines an outwardly expanding waveguide  270  using a different housing arrangement. Unlike the rear waveguide member  123  shown in  FIG. 2  which extends outwardly from the front housing member  121 , the rear waveguide member  223  in  FIGS. 3-10  extends from the rear housing member  210   a . Stated differently, the rear waveguide member  223  and the rear housing member  210  constitute a respective portions of a unitary construct. 
     In  FIG. 3 , the front housing  210   b  defines a tilted grille region  251 . Stated differently, the front grille region  251  defines a central axis of symmetry generally being coextensive with an axis of symmetry defined by the speaker transducer, as indicated in  FIG. 4 . The overlapping axes of symmetry are tilted with regard to the axis  102  shown in  FIG. 2  and defined by the circumferential housing wall  231  ( FIG. 4 ). Notwithstanding the canted speaker transducer, the waveguide  270  extends radially outward of the axis  102 , similarly to the waveguide  170  shown in  FIG. 2 . Desirably, the area of the exhaust is between about 3- and about 5-times as large as the inlet to the ports  224   a - d , such as between about 3.5- and about 4.5-times as large, with about 4-times as large being one particular example. 
     As  FIG. 4  indicates, other port embodiments can be defined by an aperture extending through a boundary surface other than a boundary wall. In the embodiment shown in  FIGS. 4 and 5 , the aperture, or port, is defined by the cross-member  229  spaced from the circumferential wall  231 , and is covered by an acoustic mesh  271  to damp the ports. 
     More specifically, the rear housing member  210   a  defines a spatially distributed acoustic port  224   a, b, c , and  d , as shown for example in  FIGS. 3 and 6 . An exemplary configuration of such a distributed acoustic port is described with particular reference to  FIGS. 5 and 6 . The housing  210   a  defines four ports  224   a - d . Each port defines an entry aperture opening from the rear chamber  230 , as indicated by the arrow  273   a . The entry aperture is defined by a cross-bar  229   a - d  extending inwardly of the outer wall  231 . An exhaust aperture opens from the port 
     The rear wall  223  defines a radially extending surface  225 . Recessed “below” (with reference to the inverted rear housing shown in  FIG. 6 ) and substantially parallel to the surface  225 , the port  224   a - d  defines an exhaust aperture between the cross-bar  229   a - d  and the circumferential outer wall  231 . Also recessed from the surface  225  is a shoulder  273   a - d  extending around an outer periphery of each aperture. 
     As shown in  FIG. 7 , the acoustic mesh or other acoustic damper  271   a - d  can overlie each exhaust aperture. The acoustic mesh can be affixed (e.g., by an adhesive) to the recessed shoulder  273   a - d . In  FIG. 8 , a gasket  272  (also shown in  FIG. 5 ), e.g., a closed-cell urethane foam, can extend circumferentially around the surface  225 , and partially overlie the mesh  271   a - d . The gasket shown in  FIG. 7  leaves an acoustic passage between the rear chamber  230  and the outwardly extending waveguide  270 . A suitable gaskets materials are well known. Some gaskets can be made from a urethane commercially available from the Rogers Corporation under the tradename PORON®. Other materials that can prevent airflow from bypassing the ports  224   a - d  (or port  124 ) can be used for the gasket. 
     In  FIGS. 9 and 10 , the mesh  371   a - d  is placed over the inlet to the port, rather than the exhaust  329   a - d . The mesh can be affixed to the cross-member  337   a - d , and the gasket  272  can be placed around the rear chamber, as shown in  FIG. 10 . In the example shown in  FIG. 10 , the wall  339  can have a curved contour  366   a - d  to ensure the cross-sectional area expands smoothly from the inlet aperture to the exhaust aperture  329   a - d  of the port  224   a - d . Other features of the rear housing  300  having similar structure to the rear housing  210   a  have reference numerals incremented by 100. 
     In  FIGS. 9 and 10 , an outermost housing member  395  overlies the generally dome shaped member rear housing. The outermost housing member  395  defines a suitable enclosure for, for example, digital signal processing components, microphones, processors, and other headphone components. A circumferential wall  393  extends into the channel defined by the outer wall  326  and the inner wall  331 . 
     Other Embodiments 
     The examples described above generally concern acoustic echo cancellation techniques and related systems. Incorporating one or more principles disclosed herein, it is possible to attenuate a wide-variety to noise spectra (e.g., spectra other than audible noise, such as electromagnetic interference, etc.). 
     Other embodiments than those described above in detail are contemplated based on the principles disclosed herein, together with any attendant changes in configurations of the respective apparatus described herein. For example, an acoustic port need not have any particular cross-sectional shape. In some instances, for example, an acoustic port can extend circumferentially around a boundary of a rear chamber. Similarly, the acoustic damper need not be discrete segments, as shown in the accompanying drawings, but rather can be distributed to a similar or lesser extent as the port(s) with which the damper is associated. For example, with a circumferentially extending, annular port, a corresponding acoustic damper can be a continuous annular damper having a unitary construction, or the damper can be formed of several juxtaposed annular sectors (e.g., arcuate segments) when assembled end-to-end form an annulus being coextensive with the circumferential port. 
     Directions and other relative references (e.g., up, down, top, bottom, left, right, rearward, forward, etc.) may be used to facilitate discussion of the drawings and principles herein, but are not intended to be limiting. For example, certain terms may be used such as “up,” “down,”, “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” and the like. Such terms are used, where applicable, to provide some clarity of description when dealing with relative relationships, particularly with respect to the illustrated embodiments. Such terms are not, however, intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface simply by turning the object over. Nevertheless, it is still the same surface and the object remains the same. As used herein, “and/or” means “and” or “or”, as well as “and” and “or.” Moreover, all patent and non-patent literature cited herein is hereby incorporated by references in its entirety for all purposes. 
     The principles described above in connection with any particular example can be combined with the principles described in connection with another example described herein. Accordingly, this detailed description shall not be construed in a limiting sense, and following a review of this disclosure, those of ordinary skill in the art will appreciate the wide variety of filtering and computational techniques can be devised using the various concepts described herein. Moreover, those of ordinary skill in the art will appreciate that the exemplary embodiments disclosed herein can be adapted to various configurations and/or uses without departing from the disclosed principles. 
     The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the disclosed innovations. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of this disclosure. Thus, the claimed inventions are not intended to be limited to the embodiments shown herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the features described and claimed herein. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 USC 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for”. 
     Thus, in view of the many possible embodiments to which the disclosed principles can be applied, we reserve to the right to claim any and all combinations of features described herein, including, for example, the combinations of features recited in the following paragraphs and all that comes within the scope and spirit of the foregoing description.

Metadata:
Filing Date: 20160629
Publication Date: 20180828
Grant Date: 20180828
Priority Date: 20150630
Inventors: BRUSS, JOHN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R1/2826", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/2849", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/2857", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2888", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2400/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2201/029", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2865", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1075", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2201/029", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2888", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/2865", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2857", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2849", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/2826", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1075", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1075", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2400/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2888", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/2865", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/2857", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 57684399