Abstract:
Methods, systems and apparatus are described for mitigating noise during sound recording. A noise mitigating microphone attachment comprises a foam structure. A first cavity extending from a first opening at a surface of the foam structure and into the foam structure. A microphone is inserted into the first cavity with sound receiving elements of the microphone fully installed in the structure. A second cavity extending from a second opening at the surface of the foam structure and into the foam structure is configured to receive sound from a sound source. The first cavity is fluidly connected to the second cavity within the foam structure so that a junction is formed between the first cavity and the second cavity. The junction, the sound cavity, and the sealing of the microphone work to shield the sound receiving elements of the microphone from sound other than received through the second opening.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation-in-part application of and claims priority to U.S. patent application Ser. No. 13/604,589, filed Sep. 5, 2012 (Attorney Docket No. 94821-849332), the entire contents of which are herein incorporated by reference for all purposes. 
     
    
     BACKGROUND 
       [0002]    When a microphone is used to record a performance in a space that has not been treated for sound recording, sound that is unrelated to the performance may be picked up by the microphone. Ambient noise or “room tone” can include noise originating within the space, such as the sound of an air conditioner or computer fan in the room. Noise entering the space from the exterior, such as traffic noise, may also contribute to ambient noise levels. Ambient noise that is picked up by a microphone during the recording of a performance can detract from the quality of the recording. 
         [0003]    Additionally, performance sound can be reflected from interior surfaces of the space, such as walls, ceiling, floor, furniture, etc. When the reflected sound waves arrive at the microphone, the reflected sound waves may be out of phase with the sound waves traveling directly from the performer to the microphone. These reflected sound waves may be picked up by the microphone as a muddled version or echo of the performance. 
         [0004]    Because of these issues, performances are often recorded in a room that is specially treated for sound recording. For example, the interior surfaces of the room may be treated with sound absorbing materials to reduce reflections of performance sound within the room. The windows and doors of the room may be reinforced or constructed from materials designed to reduce the intrusion of exterior noise into the space. Additional measures may be taken to reduce machine noise in the room. Such measures can make treating a room for sound recording a costly and complicated endeavor. Moreover, when sound recording occurs within a home, it may be undesirable to alter the appearance of the room as needed to accommodate sound recording. 
         [0005]    Portable sound recording booths may be set up within a room that is not treated for sound recording. The portable sound recording booth may have walls and a ceiling treated with sound absorbing material to reduce the amount of reflected sound picked up by a microphone. The booth may be costly, require a complicated assembly process and, when assembled, can occupy a substantial amount of space within a room. 
         [0006]    Embodiments of the invention solve these and other problems. 
       BRIEF SUMMARY 
       [0007]    Methods and apparatus are described for mitigating noise with a portable microphone attachment. 
         [0008]    According to one embodiment, an attachment for a microphone comprises a foam structure. A first cavity extends from a first opening at a surface of the foam structure and into the foam structure. The first cavity is configured to seal a mobile device at least partly in the cavity. The attachment also has a second cavity extending from a second opening at the surface of the foam structure and into the foam structure. The second opening receives sound from a sound source. The first cavity is fluidly connected to the second cavity within the foam structure so that a junction is formed between the first cavity, the second cavity, and the sealing of the mobile device. The junction works to shield the sound receiving elements of a microphone coupled to the mobile device from sound other than the sound received through the second opening. 
         [0009]    In a another embodiment, a method for mitigating noise comprises receiving a mobile device through a first opening of a foam structure into a first cavity in the foam structure. A microphone coupled to the mobile device extends into a second cavity in the foam structure. The second cavity is fluidly connected to the first cavity within the foam structure and extends from a second opening at a surface of the foam structure. Performance sound is received from a performance sound source via the second cavity. Sound waves incident on an exterior surface of the second cavity are attenuated by the foam structure. 
         [0010]    To better understand the nature and advantages of the present invention, reference should be made to the following description and the accompanying figures. It is to be understood, however, that each of the figures is provided for the purpose of illustration only and is not intended as a definition of the limits of the scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  shows an illustrative noise mitigating microphone attachment, according to an embodiment. 
           [0012]      FIG. 2  shows an illustrative pop filter, according to an embodiment. 
           [0013]      FIG. 3  illustrates the insertion of a pop filter and a microphone into an illustrative noise mitigating microphone attachment, according to an embodiment. 
           [0014]      FIG. 4  is a front view of an illustrative noise mitigating microphone attachment shown seated in a shock mount, according to an embodiment. 
           [0015]      FIG. 5  is an illustrative flowchart of a process for mitigating noise during a recording with a noise mitigating microphone attachment, according to an embodiment. 
           [0016]      FIG. 6  shows an illustrative noise mitigating microphone attachment having a cavity configured to receive a mobile device. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Embodiments of the present invention relate to mitigating noise during a capture of sound recording with a noise mitigating microphone attachment. Noise can refer to any unwanted sound, i.e., sound that is not desirable to have a microphone detect during a recording. For example, it may be desirable that noise such as ambient noise and reflections of sound waves originating from a performance sound source is mitigated. The noise mitigating microphone attachment can reduce the amount of noise that a microphone will pick up during a sound recording. 
         [0018]    The noise mitigating microphone attachment is typically a foam structure, such as a foam sphere. The noise mitigating microphone attachment can have two openings. A microphone can be inserted through one of the openings into a first hollow cavity (“microphone cavity”) within the foam structure. The second opening may be placed proximate to a sound source, such as a vocalist or an instrument. Sound radiating from the sound source travels through the second opening into a second hollow cavity (“sound cavity”). The microphone cavity and the sound cavity can intersect, allowing sound from the sound source to travel to the microphone via the sound cavity. In some embodiments, the microphone can extend through the microphone cavity into the sound cavity. In other embodiments, the microphone may be coupled to a mobile device that extends through the microphone cavity into the sound cavity. 
         [0019]    In some embodiments, a microphone coupled to a mobile device is used with the noise mitigating microphone attachment. Where the term “microphone” is used herein, a mobile device or other device having a microphone attachment may be used. For example, a mobile device can extend through the microphone cavity such that a microphone connected to the mobile device extends into the sound cavity. 
         [0020]    The microphone can be attached to the foam structure by an elastic coupling between the microphone and the foam structure. The elastic coupling may form a seal around the casing of microphone. The seal can reduce the amount of noise that enters the sound cavity through the microphone cavity. 
         [0021]    The structure (e.g., foam) surrounding the sound cavity can be a sound attenuating material for attenuating sound waves incident on the exterior surface of the sound cavity, such that sound waves traveling through the structure into the sound cavity are attenuated. In some embodiments, the structure can absorb sound incident on the exterior surface of the noise mitigating microphone attachment. The structure may additionally attenuate sound waves incident on the interior surface of the sound cavity, such that sound waves traveling through the structure from the sound cavity to the exterior of the structure are attenuated. The structure can further absorb noise incident on the interior surface of the sound cavity. Performance sound received at the opening into the sound cavity can be channeled along the sound cavity to the microphone. 
         [0022]      FIG. 1  shows a side view of a noise mitigating microphone attachment according to an embodiment. Noise mitigating microphone attachment  100  can include structure  102  having a sound cavity  104  and a microphone cavity  108 . In some embodiments, structure  102  is a foam having sound absorbing properties. For example, structure  102  may be polyurethane foam, such as an open cell polyurethane foam. The foam may have an Indentation Force Deflection (IFD) at 25% deflection between 40 and 150 pounds per 50 square inches (lb./50 in. 2 ), such as 65 to 70 lb./50 in. 2 , e.g., 70 lb./50 in. 2 . The foam may have a density threshold between 1.5 and 3.5 pounds per cubic foot (PCF), such as 2.45-2.65 PCF, e.g., 2.5 PCF. Polyurethane foam may be fabricated in a mold. The foam can be fabricated with an integral skin or may be fabricated or modified to have no integral skin. In a preferred embodiment, the foam has no integral skin. 
         [0023]    Structure  102  may have a spherical shape. The spherical shape can allow the noise mitigating microphone attachment to be supported within a shock mount, as described further below. Polyurethane foam may experience discoloration over time, and such discoloration may be relatively inconspicuous on a form having a spherical shape (compared with other shapes) due to even exposure of the sphere&#39;s surface to air. Structure  102  may be a sphere having a diameter in the range of 2 inches to 36 inches, such as 4 inches to 12 inches, e.g. 7.6 inches. The spherical shape may also facilitate seating of the noise mitigating microphone attachment within a shock mount. This allows the noise mitigating microphone attachment to be used with a microphone mounted to a microphone stand with a shock mount. 
         [0024]    Sound cavity  104  may extend from an opening  106  at the surface of structure  102 . In some embodiments, sound cavity  104  has a cylindrical shape. A cylindrical shape can allow even absorption and/or reflection of sound around the circumference and along the interior of sound cavity  104 . It will be understood that due to sound absorbing characteristics of the material of which structure  102  may be composed, reflection of sound occurring within sound cavity  104  may be low or negligible. Sound cavity  104  may have a diameter in the range of 1 inch to 12 inches, such as 4 inches to 5 inches, e.g. 4¼ inches. Sound cavity  104  may have a length in the range of 3 inches to 15 inches, such as 5 inches to 6 inches, e.g. 5½ inches. The distance from sound cavity  104  to the outer surface of structure  102  may be in the range of 1 inch to 6 inches, such as 1½″ to 3 inches, e.g., 2 inches. 
         [0025]    Microphone cavity  108  may extend from an opening  110  at the surface of structure  102  and may intersect sound cavity  104 . In some embodiments, microphone cavity  108  has a cylindrical shape. A cylindrical shape can allow microphone cavity  108  to accommodate microphones having a variety of casings, such as cylindrical casings, rectangular casings, etc. A microphone may be inserted into microphone cavity  108  via opening  110 . The microphone may extend through microphone cavity  108  into sound cavity  104 . Microphone cavity  108  may have a diameter in the range of ⅛ inch to 3 inches, such as 1 inch to 2 inches, e.g. 1¾ inches. Microphone cavity  108  may have a length in the range of 1 inch to 8 inches, such as 1½ inches to 3 inches, e.g. 2 inches. 
         [0026]    In some embodiments, microphone cavity  108  may have a rectangular, square, ovoid, or other non-circular cross section to receive a microphone, mobile device, or other device having a non-circular cross section. For example, a microphone used with microphone attachment  100  may be coupled to a mobile device, such as a cellular phone, having a rectangular cross section. Microphone cavity  108  may have a rectangular cross-sectional area configured to receive a mobile device that has a rectangular cross-sectional area. When the mobile device is inserted into microphone cavity  108 , microphone cavity  108  may seal the mobile device into the cavity. Alternatively, a converter insert, such as a circular-profile-to-rectangular-profile converter insert may be inserted into microphone cavity  108  to accommodate a microphone, mobile device, or other device having a cross sectional area that differs from the cross-sectional area of microphone cavity  108 . The converter insert may include one or more pieces of foam material. When inserted into microphone cavity  108  along with a device, the converter insert can seal the device within microphone cavity  108 . 
         [0027]    In another embodiment, microphone attachment  100  may have a slit or hole in lieu of microphone cavity  108 . For example, the slit or hole may be just large enough to allow a cable, such as a microphone cable, to pass from the exterior of microphone attachment  100  to a microphone or mobile device that is fully or partially located in sound cavity  104 . A slit used in lieu of microphone cavity  108  may be located at the position of opening  110 . Alternatively, the slit may be located opposite opening  106 , such that a cable passing through the slit to the microphone is parallel to the longitudinal axis of sound cavity  104 . 
         [0028]    The microphone can be located at a distance from opening  106 , such a distance in a range of 1 inch to 8 inches, such as 1½ inches to 4 inches e.g., 2½ inches. The microphone can also be located at a distance from the end of sound cavity opposing opening  106 , such as a distance in a range of 1 inch to 8 inches, such as 2 to 5 inches, e.g., 3 inches. Locating the microphone at a distance from opening  106  allows noise entering sound cavity  104  to interact with absorptive interior surface of sound cavity  104  before arriving at a microphone in microphone cavity  108 . For example, the noise may enter sound cavity at an angle such that it is absorbed by the interior surface of sound cavity  104 . Sound cavity  104  may have a minimal effect on performance sound travelling directly from the performance sound source to the microphone. 
         [0029]    Sound cavity  104  and microphone cavity  108  may be oriented at a variety of angles with respect to one another. For example, the longitudinal axis of sound cavity  104  and the longitudinal axis of microphone cavity  108  may be perpendicular with respect to one another, as shown in the illustrative example of  FIG. 1 . In other embodiments, the longitudinal axis of sound cavity  104  may be aligned with the longitudinal axis of microphone cavity  108  (e.g., a single cavity extending through the noise mitigating microphone attachment can function as both microphone cavity and sound cavity, receiving a microphone at one end of the cavity and receiving sound at the other end of the cavity.) 
         [0030]    A performance sound source may be placed proximate to opening  106  of sound cavity  104 . For example, microphone attachment  100  may be positioned such that opening  106  is aligned with and facing the mouth of a vocalist. In another example,  106  may be positioned adjacent to an instrument. Typically, opening  106  would be placed at a location relative to the performance sound source similar to where a microphone would be placed for recording the performance sound source. Because microphones contain sensitive components, when the microphone lacks a protective covering, the microphone may be placed at a sufficient distance from a performance sound source in order to protect the microphone from damage. In this way, the microphone can be protected against accidental bumps by instruments or performers. The foam structure of noise mitigation microphone attachment may protect a microphone by providing impact resistance. Because the structure of noise mitigating microphone attachment  100  can protect the microphone from jarring or bumping, opening  106  of noise mitigating microphone attachment  100  can be placed closer to a performance sound source than a microphone would be placed without the attachment. 
         [0031]    In some embodiments, a plurality of microphone attachments  100  may be used when performance sound is being captured. For example, when a collection of instruments, such as a collection of percussion instruments (e.g., a drum set), is used for a performance, a different microphone may be used to simultaneously record each instrument of the collection of instruments. A microphone attachment  100  may be used with each microphone. Opening  106  of sound cavity  104  for each microphone attachment of the plurality of microphone attachments may be positioned to face a different part of a drum set or other collection of instruments. In an illustrative example, a microphone can be placed in a “close-miked” position (e.g., 1 to 12 inches, such as 2 to 4 inches) relative to each drum of a drum set and a microphone can be placed in a close-miked position relative to each of one or more cymbals. 
         [0032]    In another example, the performance of multiple performers may be captured with a plurality of microphones and an attachment  100  for each microphone. For example, if multiple microphones are used simultaneously to capture the performance of a musical group having one or more vocalists and/or one or more instrumentalists, an attachment  100  may be used with each microphone. Opening  106  of sound cavity  104  for each microphone attachment of the plurality of microphone attachments may be positioned to face each of (or groups of) the vocalists and/or instruments. 
         [0033]    In a further embodiment, microphone attachment  100  may be used with a boom microphone or other microphone used to capture performance sound during video or other motion picture recording. A boom microphone is typically located at one end of a boom pole. The other end of the boom pole may be handled or otherwise managed by a boom operator. The boom microphone can be used to capture performance sound associated with an actor or action by placing the boom microphone in proximity to the actor or action but outside of a camera&#39;s frame. Opening  106  of sound cavity  104  may be positioned such that it faces the actor or action that is the sound source of interest. 
         [0034]      FIG. 2  shows a pop filter  200  that can be coupled to a noise mitigating microphone attachment, according to an embodiment. For example, pop filter  200  can be inserted into opening  106  of attachment of noise mitigating microphone attachment  100 . A pop filter can be used to reduce and/or eliminate popping sounds caused when plosive sounds (such as sound that may occur when the letter “B” or “P” is pronounced) and sibilants (such as sound that may occur when the letter “S” or “Z” is pronounced) are recorded by a microphone. Pop filter  200  can include base  206  and lip  204 . Base  206  and lip  204  can be metal, plastic, or other material. Base  206  and lip  204  can be fabricated as a single part. Lip  204  may extend beyond opening  106  over the surface of structure  102 . Pop filter  200  can include mesh  202  extending across the area defined by the interior circumference of lip  204 . Mesh  202  may be, e.g., a polyester, metal, or nylon mesh. It will be recognized that a variety of materials or structures could be used as a pop filter in conjunction with a noise mitigating microphone attachment. 
         [0035]      FIG. 3  illustrates the insertion of elements such as a pop filter and microphone into noise mitigating microphone attachment structure  300 , according to an embodiment. Pop filter  302  may correspond to pop filter  200  described with reference to  FIG. 2 . Pop filter  302  can be inserted into opening  306  of structure  300 . The material of structure  300  may be resilient such that pop filter can be inserted within opening  306  of structure  300  and held in place relative to structure  300  by the material of structure  300 . 
         [0036]    Microphone  304  can be inserted into microphone cavity  308  of noise mitigating microphone attachment  300 . The material of structure  300  may be resilient such that different sizes of microphones can be accommodated by microphone cavity  308 . In some embodiments, when microphone  304  is inserted into opening  308  of structure  300 , the material of structure  300  elastically couples noise mitigating microphone attachment  300  to microphone  304 . If a base of microphone  304  is too narrow to fit snugly within opening  308 , an insert, such as a foam collar insert, may be placed around the microphone casing. In this manner, the diameter of the microphone base may be increased such that the microphone base can fit snugly within opening  308 . When microphone  304  is inserted in opening  308 , elastic coupling between the casing of microphone  304  (or a collar tightly secured around microphone  304 ) and opening  308  may form a seal. The seal can reduce the amount of noise that enters the sound cavity through the microphone cavity. In some embodiments, the elastic coupling between microphone  304  and opening  308  can allow the noise mitigating microphone attachment to be suspended from microphone  304  (i.e., as if  FIG. 3  were rotated 180 degrees). 
         [0037]    Microphone  304  can include sound receiving elements  310  and casing  312 . Sound receiving elements  310  can include elements such as a capsule, diaphragm, protective elements, and the like. Microphone  304  can be any of a wide variety of microphones. The microphone type may be, for example, condenser, electret condenser, dynamic, etc. Typically, microphone  304  is a microphone designed for use in a recording studio environment, although it will be recognized that other microphones may be used. Microphone  304  may have any polar pattern, such as omnidirectional, cardioid, hypercardioid, supercardioid, etc. 
         [0038]    The noise mitigating microphone attachment can improve the performance of an omnidirectional microphone for recording performance sound. As will be recognized by those skilled in the art, an omnidirectional microphone may be undesirable when a microphone is used for recording a performance from a particular sound source, such as a vocal performance, because the omnidirectional microphone will pick up sound arriving directly from the vocalist and sound from other directions (e.g., environmental noise and reflected sound from the performance sound source) approximately equally. In contrast, when a noise mitigating microphone attachment is used with an omnidirectional microphone, the noise mitigating microphone attachment receives direct performance sound via the sound cavity and can attenuate and/or absorb sound arriving from other directions. 
         [0039]      FIG. 4  is a front view  400  of a noise mitigating microphone attachment shown seated in a shock mount, according to an embodiment. In some embodiments, noise mitigating microphone attachment  402  can be seated in a shock mount  404 . A shock mount is a mechanical fastener that can suspend a microphone in elastics that are attached to a microphone stand such that transmission of vibrations from the microphone stand to the microphone is minimized. The shape of the noise mitigating microphone attachment allows it to be used with a microphone mounted in a shock mount. The noise mitigating microphone attachment can also be used with a microphone mounted directly to a microphone stand. 
         [0040]    To mount noise mitigating microphone attachment  402  within shock mount  404 , the noise mitigating microphone attachment  402  is seated within a cradle formed by the upper arms of shock mount  404 . In this manner, the noise mitigating microphone attachment  402  is held in place relative to shock mount  404  by gravity. 
         [0041]      FIG. 5  is a flowchart of a process  500  for channeling sound during a recording with a noise mitigating microphone attachment, according to an embodiment. 
         [0042]    At block  502 , a microphone can be inserted into a first opening, such as opening  110  of microphone cavity  108 , of a noise mitigating microphone attachment  100 . At block  504 , the microphone can be extended through first cavity  108  into a second cavity, such as sound cavity  104 , of the noise mitigating microphone attachment  100 . At block  506 , a performance sound source, such as the mouth of a vocalist, can be positioned proximate to a second opening, such as opening  106 , of the noise mitigating microphone attachment. At block  508 , the microphone can be used to record sound waves from the performance sound source that enter the second cavity via the second opening. 
         [0043]      FIG. 6  shows an illustrative microphone attachment  600  having a microphone cavity  610  with a rectangular profile. In some embodiments, microphone cavity  610  may be configured to receive a mobile device  612  with microphone attachment  614 . Microphone cavity  610  may extend from an opening  610  at the surface of structure  102  and may intersect sound cavity  104 . 
         [0044]    Mobile device  612  may be a cellular phone, tablet, media player, or other handheld electronic device. Microphone  614  may be a microphone that is configured to couple physically and/or mechanically to a mobile device. For example, microphone  614  may couple to mobile device  612  via connector of the mobile device such as a USB, ⅛-inch, 30-pin or other connector. Microphone  614  can be, for example, a compact microphone such as Mini Mic by VeriCorder, Flexible Mini Capsule Microphone by Brando Workshop, or Mikey by Blue Microphones. Microphone cavity  610  may have a rectangular or other shape of cross-sectional area configured to receive a device having an attached microphone. 
         [0045]    The embodiments described herein provide a portable device that can be produced at low cost relative to the cost of existing solutions for noise mitigation in recording environments. The noise mitigation microphone attachment can be used for sound recording in a home studio, outdoors, or other environment to protect a microphone from picking up unwanted sounds during a performance. A microphone can be inserted into a first opening of the noise mitigation microphone attachment and extend through a microphone cavity into a sound cavity. The sound cavity can extend from a second opening at the surface of the noise mitigating microphone attachment. A performance sound source is typically located proximate to the second opening. Sound incident on the exterior of the noise mitigating microphone attachment is attenuated by the structure of the noise mitigating microphone attachment. 
         [0046]    While the invention has been described with respect to specific embodiments, one skilled in the art will recognize that numerous modifications are possible. Thus, although the invention has been described with respect to specific embodiments, it will be appreciated that the invention is intended to cover all modifications and equivalents within the scope of the following claims.