Helmholtz resonator for microphone assembly

Abstract

This disclosure relates to a Helmholtz resonator for a microphone assembly. A sensor assembly includes a housing having an external device interface and an acoustic port leading to the interior of the housing. A transducer and circuitry are disposed within the housing. The transducer is acoustically coupled to the acoustic port, while the circuitry is electrically connected to the transducer and the external device interface. A cavity is formed in a portion of the sensor assembly. In some embodiments, this portion is the base of the housing of the sensor assembly. In other embodiments, this portion is an adapter for the acoustic port connected to the sensor assembly. In any case, the cavity is acoustically coupled to the interior of the housing via the acoustic port and includes wall portions configured to alter the acoustic characteristics of the sensor assembly.

Description

Technical Field

[0001] The present disclosure relates generally to microphone assemblies, and more particularly, to microphones having Helmholtz-resonators and other structures for modifying sound input to microphone assemblies. Background Art

[0002] Microphones are used in a variety of devices, including hearing aids, mobile phones, smart speakers, personal computers, and other devices and equipment. Microphones typically include a transducer and, in some devices, an integrated circuit disposed in a housing formed by a can or cover mounted on a base. The sound port typically extends through the base (for bottom-port devices) or through the top of the housing (for top-port devices). In either case, sound passes through the sound port and is converted into an electrical signal by the transducer.

[0003] For certain applications, microphones are exposed to ultrasonic frequencies emitted by motion sensors, proximity detectors, and other sources. These ultrasonic devices can interfere with the resonant response of the microphone and cause audible noise at its output. Therefore, users can benefit from an improved microphone design that reduces adverse effects associated with ultrasonic or other signals that would otherwise be detected by known microphone assemblies. Summary of the invention

[0004] In a first aspect, a sensor assembly is provided, comprising: a shell having an external device interface and a sound port leading to the interior of the shell; a transducer disposed in the shell and acoustically coupled to the sound port; a circuit disposed in the shell and electrically connected to the transducer and to an electrical contact on the external device interface; and a cavity formed in a portion of the sensor assembly and acoustically coupled to the interior of the shell through the sound port, the cavity having a wall portion, the wall portion being configured to change the acoustic characteristics of the sensor assembly.

[0005] Preferably, the housing comprises a base having the external device interface and the sound port, and wherein the cavity and the wall portion are formed in the base.

[0006] Preferably, the cavity and the wall portion form a Helmholtz resonator comprising a neck connected to one or more chambers.

[0007] Preferably, said sound port is acoustically coupled to said one or more chambers of said Helmholtz resonator through said neck.

[0008] Preferably, the neck of the Helmholtz resonator and the one or more chambers are formed in or on the same layer of the base.

[0009] Preferably, the neck of the Helmholtz resonator and the one or more chambers are formed in or on different layers of the base, wherein the neck is formed in or on a first layer and the one or more chambers are formed in or on a different second layer.

[0010] Preferably, the sensor assembly also includes a sound port adapter having a sound channel, the sound channel having a sound inlet and a sound outlet, the sound outlet being on the mounting surface of the sound port adapter, the sound port adapter being mounted above the sound port of the shell so that the sound outlet of the sound port adapter is acoustically coupled to the sound port, wherein the cavity and the wall portion are formed in the sound port adapter.

[0011] Preferably, said acoustic channel of said sound port adapter is acoustically coupled to said cavity.

[0012] Preferably, the acoustic properties of the sensor assembly include any one or more of inertia, acoustic resistance, compliance and resonance.

[0013] In a second aspect, a microphone assembly is provided, which includes: a shell having a surface-mountable external device interface and a sound port leading to the interior of the shell; an electroacoustic transducer disposed in the interior of the shell and acoustically coupled to the sound port; a circuit disposed in the interior of the shell and electrically connected to the electroacoustic transducer and to an electrical contact on the external device interface; and a cavity formed in a portion of the microphone assembly and acoustically coupled to the interior of the shell via the sound port, the cavity having a wall portion, and the wall portion is configured to change the acoustic characteristics of the microphone assembly.

[0014] Preferably, the cavity and the wall portion form a Helmholtz resonator comprising a neck connected to one or more chambers.

[0015] Preferably, the housing comprises a base having the surface mountable external device interface and the sound port, and wherein the Helmholtz resonator is formed in the base.

[0016] Preferably, the sound port is acoustically coupled to the one or more chambers of the Helmholtz resonator via the neck.

[0017] Preferably, the neck of the Helmholtz resonator and the one or more chambers are formed in or on different layers of the base, wherein the neck is formed in or on a first layer and the one or more chambers are formed in or on a different second layer.

[0018] Preferably, the microphone assembly also includes a sound port adapter having a sound channel, the sound channel having a sound inlet and a sound outlet, the sound outlet being on the mounting surface of the sound port adapter, the sound port adapter being mounted above the sound port of the shell so that the sound outlet of the sound port adapter is acoustically coupled to the sound port, wherein the Helmholtz resonator is formed in the sound port adapter.

[0019] Preferably, the sound inlet is located on a surface of the sound port adapter that is different from the mounting surface.

[0020] Preferably, the acoustic characteristics of the microphone assembly include any one or more of inertia, acoustic resistance, compliance and resonance.

[0021] According to a third aspect, a sound port adapter for a microphone assembly including a sound transducer is provided, wherein the sound transducer is arranged in a shell, and the shell has a sound port on the top surface or the bottom surface of the shell, and the sound port adapter comprises: a main body member having a mounting surface, which is configured to be mounted on the shell on the microphone assembly; a sound channel, which is arranged to pass through the main body member, the sound channel having a sound inlet and a sound outlet, and the sound outlet is arranged on the mounting surface of the main body member; and a Helmholtz resonator, which is arranged in the main body member, the Helmholtz resonator comprising a neck and one or more chambers, and the sound channel is acoustically coupled to the one or more chambers through the neck.

[0022] Preferably, the Helmholtz resonator changes any one or more of the resonant frequency and amplitude of sound propagating through the vocal tract of the sound port adapter.

[0023] Preferably, the sound port adapter comprises a wall portion configured to form a non-straight acoustic path in the acoustic channel.

[0024]

[0013] The various aspects, features and advantages of the present disclosure will become more fully apparent to those of ordinary skill in the art upon consideration of the following detailed description and the accompanying drawings described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present disclosure is described in more detail below in conjunction with the accompanying drawings, and in which like reference numerals represent like components:

[0026] Figure 1 is a cross-sectional view of a microphone assembly having a Helmholtz resonator formed in a base of the microphone assembly;

[0027] Figure 2 yes Figure 1 a transparent view of the base of the microphone assembly;

[0028] Figure 3 yes Figure 1 a transparent view of another configuration of the base of the microphone assembly;

[0029] Figure 4 yes Figure 1 a transparent view of yet another configuration of a base of a microphone assembly;

[0030] Figure 5 is a bottom view of a sound port adapter having a Helmholtz resonator in a first configuration;

[0031] Figure 6 It is connected to the microphone assembly Figure 5 A transparent view of the sound port adapter;

[0032] Figure 7 is a bottom view of a sound port adapter having a Helmholtz resonator in a second configuration;

[0033] Figure 8 It is connected to the microphone assembly Figure 7 A transparent view of the sound port adapter;

[0034] Fig. 9 is a bottom view of a sound port adapter having a Helmholtz resonator in a third configuration;

[0035] Fig.10 It is connected to the microphone assembly Fig. 9 A transparent view of the sound port adapter;

[0036] Fig.11 yes Figure 1 A cross-sectional view of another embodiment of a microphone assembly; and

[0037] Fig.12 yes Fig.11 A transparent view of the base of the microphone assembly. DETAILED DESCRIPTION

[0038] According to one aspect of the present disclosure, a sensor assembly includes a housing having an external device interface and a sound port leading to the interior of the housing. A transducer is disposed within the housing and acoustically coupled to the sound port. A circuit is also disposed within the housing and electrically coupled to the transducer and to an electrical contact on the external device interface. A cavity is formed in a portion of the sensor assembly and acoustically coupled to the interior of the housing via the sound port. The cavity has a wall portion configured to change the acoustic properties of the sensor assembly, such as any one or more of inertia, acoustic resistance, compliance, and resonance. In one example, the sensor assembly is a microphone. In other examples, the sensor assembly includes other sensor types such as pressure sensors, accelerometers, gas sensors, mass flow sensors, and the like.

[0039] In various embodiments, the cavity and the wall portion form a Helmholtz resonator that changes any one or more of the resonant frequency and amplitude of sound propagating through the sound port. The Helmholtz resonator is configured with a neck connected to one or more chambers, wherein the sound port is acoustically coupled to the one or more chambers via the neck.

[0040] In some embodiments, the cavity and wall portions forming the Helmholtz resonator are arranged in the base of the sensor assembly. The base is an integral part of the housing and includes an external device interface and a sound port. In one implementation, the neck and one or more chambers are formed in or on the same layer of the base. In another implementation, the neck and one or more chambers are formed in or on different layers of the base, wherein the neck is formed in or on the first layer and one or more chambers are formed in or on different second layers. In other embodiments, other suitable neck and chamber implementations are contemplated.

[0041] In some embodiments, the cavity and wall portions forming the Helmholtz resonator are disposed in a sound port adapter that can be assembled to the sensor assembly. The sound port adapter includes a sound channel that is acoustically coupled to the cavity. The sound port adapter includes a sound outlet and a sound inlet disposed on a mounting surface. When the mounting surface is coupled to a surface (e.g., a base) of the sensor assembly, the sound outlet is acoustically coupled to the sound port.

[0042] According to another aspect of the present disclosure, a sound port adapter for a microphone assembly includes a main body member having a mounting surface and a sound channel arranged to pass through the main body member. The sound channel includes a sound inlet and a sound outlet. The main body member is configured to be mounted on a surface (e.g., a top surface or a bottom surface) of the microphone assembly on which the sound port is arranged. A Helmholtz resonator including a neck and one or more chambers is arranged in the main body member. The sound channel is acoustically coupled to one or more chambers through the neck.

[0043] In some embodiments, the body member includes a wall portion configured to form a non-straight sound path in the sound channel to change any one or more of the inertia and acoustic resistance of the sound channel. In other embodiments, the body member includes a wall portion configured to prevent debris from entering the sound channel to achieve ingress protection.

[0044] In various applications, sound attenuation devices such as Helmholtz resonators may be used to reduce or attenuate acoustic signals at specific frequencies (eg, high frequencies) at the input of a microphone or other sensor. Figures 1 to 10 Different configurations of Helmholtz resonators for such a sensor assembly are shown. Figures 1 to 4 In the embodiment of the invention, the Helmholtz resonator is arranged in the base of the microphone assembly. Figures 5 to 10 In the embodiment of the present invention, the Helmholtz resonator is configured in a sound port adapter that can be assembled to the sound port of the microphone assembly. If desired, the sound port adapter can be configured for other acoustic tuning (e.g., inertia, acoustic resistance, compliance) and / or ingress protection (e.g., preventing debris from entering the sound port).

[0045] A sensor assembly typically includes various components enclosed in a housing. Figure 1 A cross-sectional view of a microphone assembly 100 is shown. The microphone assembly includes a transducer 102 and a circuit 104 (e.g., an integrated circuit) disposed in a housing 105 having a cover or cap 106 mounted on a base 108 having a sound port 110. The transducer, circuit, and sound port are all disposed within the interior of the housing. The transducer is acoustically coupled to the sound port, and the circuit is electrically coupled to the transducer and to electrical contacts 112 on an external device interface (see Figure 2 ). In one implementation, the external device interface is a surface mount interface suitable for integrating the microphone assembly into a host device, for example, by reflow soldering or wave soldering or some other known or future surface mount technology. Figure 1 A micro-electromechanical system (MEMS) capacitive transducer having one or more diaphragms 103 is shown, but other types of transducers are contemplated in other embodiments (eg, capacitive, piezoelectric, optical, electro-acoustic, etc.) Additionally, the transducer is not necessarily limited to an acoustic transducer.

[0046] The converter is configured to convert sound into an electrical signal. Once converted, the circuit conditions the electrical signal before providing the conditioned signal at the external device interface. Such conditioning may include buffering, amplification, filtering, analog-to-digital (A / D) conversion for digital devices, and signal protocol formatting, among other processing. Figure 1The microphone assembly of exemplifies a bottom port device having a transducer mounted on a base and in acoustic communication with a sound port. In other embodiments, the microphone assembly may be a top port device having a transducer mounted above a sound port on a cover.

[0047] In order to change the acoustic characteristics of the microphone assembly, a tuning structure may be formed in a portion of the microphone assembly. Figure 1 to Figure 2 In the embodiment of the present invention, the tuning structure is a cavity 114 having a wall portion 116 formed in the base of the microphone assembly. The cavity is acoustically coupled to the interior of the housing via or through the sound port. The cavity is partially defined by side walls 118, 120. The wall portion includes wall segments 122, 124 and defines an opening 126 connected to the sound port. The opening allows sound to enter the cavity and move to the sound port. The cavity and wall portion can be made by using laser drilling, manual drilling or other suitable techniques.

[0048] like Figure 1 to Figure 2 As shown in , the cavity and wall portions are configured to form a Helmholtz resonator that operates to change the resonant frequency and / or resonant amplitude of sound propagating through the sound port (e.g., attenuate the resonant amplitude, change the resonant frequency, etc.). The Helmholtz resonator includes a narrow opening or neck 130 connected to a chamber 131. In this example, the chamber includes two chambers 132, 134. The neck is formed between the wall segments, and each of the two chambers is formed between the corresponding wall segment and the side wall.

[0049] The neck acoustically couples the sound port to the two chambers. Figure 2 As shown in FIG. 2 , there are gaps 202, 204 between the ends 206, 208 of the wall segments and the perimeter 210 of the cavity. The corresponding surfaces 212, 214 of the wall segments also meet the surface 216 of the sound port. In this way, the sound coming from the opening moves through the neck and into the cavity via the gap, and then travels back through the neck into the sound port. Although Figure 2 The chambers in are shown as two finger-shaped chambers with rounded tops, but any number of other suitable shaped chambers are contemplated. In fact, it is the enclosed volume defined by the chambers that forms part of the Helmholtz resonator design. Therefore, in other embodiments, other suitable neck and chamber configurations for the Helmholtz resonator are contemplated.

[0050] Despite Figure 1 to Figure 2 A microphone is shown in FIG, but the Helmholtz resonator can be applied to any type of sensor (e.g., pressure sensor, gas sensor, etc.). More generally, any device can be equipped with a Helmholtz resonator for resonance tuning. Additional structures can be added to achieve other acoustic tuning features such as inertial, acoustic resistance, and / or compliance tuning if desired.

[0051] Different techniques can be used to embed the Helmholtz resonator into the base of the microphone assembly. The base can include various layers of material (e.g., FR-4, epoxy, plastic, ceramic, fiberglass, etc.). Figure 2 In the embodiment, the neck and the cavity of the Helmholtz resonator are formed in or on the same layer of the base. Figure 3 In the embodiment of the present invention, the neck and the cavity of the Helmholtz resonator are formed in or on different layers of the base. For example, the neck is formed in or on a first layer 302, and the cavity is formed in or on a different second layer 304. A plurality of pillars 306 may be used to support the cavity in the second layer. The first layer and the second layer may be made of the same or different materials. Figure 3 As shown in , the cavity is divided into a first layer and a second layer, wherein the first layer is thinner than the second layer. However, in other embodiments, other configurations of the cavities in different layers are contemplated.

[0052] Figure 4 Another configuration of a Helmholtz resonator in the base of a microphone assembly is shown. In this example, the chamber is a single chamber connected to the neck. The single chamber covers almost the entire cavity, wherein the cavity covers almost the entire base. The single chamber can be formed by etching inside the base and around the neck, sound port, and electrical contacts. Figure 4 In the embodiment, the base is made of a copper material, although other suitable materials are contemplated in other embodiments.

[0053] In some embodiments, as an alternative to having a tuning structure in the base of the sensor assembly, the sound port adapter may be configured with tuning structures for changing various acoustic properties of the sensor assembly (e.g., inertia, acoustic resistance, compliance, and / or resonance). Figures 5 to 10 Different configurations of a one-piece sound port adapter that can be assembled to a microphone assembly are shown. The sound port adapter can be made of any suitable material (e.g., metal, plastic, ceramic, glass, etc.) using any suitable technique such as etching, laser ablation, molding, 3D printing, etc. Although Figures 5 to 10 The sound port adapter is shown as being square in shape, but other suitable shapes are contemplated in other embodiments (e.g., rectangular, trapezoidal, oval, etc.).

[0054] Figure 5 A sound port adapter 500 is shown that includes a body member 502 having a mounting surface 506. The mounting surface includes a sound channel 507 defined by side walls 508, 509. The sound channel is provided through the body member to create a sound inlet 510 and a sound outlet 512.

[0055] The body member includes a Helmholtz resonator formed by a cavity and a wall portion. Here, the wall portion includes wall segments 514, 516 that extend horizontally (e.g., parallel to the sound inlet) into the cavity to define a neck of the Helmholtz resonator. The chamber of the Helmholtz resonator is defined by these two wall segments and a third side wall 518. In this way, the sound channel is acoustically coupled to the chamber through the neck. The chamber is shown to have rounded corners 520, 522, although other shapes are contemplated. Although in Figure 5 A rectangular shaped chamber is shown in FIG. 1 , but any number of other suitable shaped chambers are contemplated in other embodiments.

[0056] Figure 6 A sound port adapter is shown mounted to a microphone assembly that may be identical to microphone assembly 100, except that the base does not include a Helmholtz resonator. When mounted to the base, the sound outlet is acoustically coupled to the sound port and the sound inlet defines a side port location. In other words, the sound port adapter converts the microphone assembly from a bottom port microphone assembly to a side port microphone assembly.

[0057] To facilitate installation of the sound port adapter, the surface 602 of the housing on which the sound port is disposed may include a ground plane 604. The shape of the ground plane may correspond to the side walls of the sound port adapter so that the side walls can be attached to the ground plane (e.g., by using solder or glue). The surface may also include a plurality of contact pads 606-610 for external device interfaces (e.g., supply voltage, clock, data, etc.).

[0058] exist Figures 7 and 8 In addition to forming a Helmholtz resonator, the wall portion also includes a plurality of discrete wall portions 702-712 arranged horizontally (e.g., parallel to the sound inlet) across the sound channel. The discrete wall portions are used to change the acoustic impedance of the sound channel. In this example, the discrete wall portions are implemented as six equally sized cylindrical pillars. However, in other embodiments, any number of appropriately sized shapes that repeat the pattern are contemplated.

[0059] The discrete wall portions are arranged in a spaced relationship with each other, and the distance between the discrete wall portions can be adjusted as required. The space between the discrete wall portions forms a sound inlet to enable sound to travel to the sound outlet. The arrangement also acts like a net or screen to prevent debris from entering the sound channel.

[0060] exist Figures 9 and 10In addition to forming a Helmholtz resonator, the wall portion also includes a discrete wall portion in the curved sound channel. In this example, the wall portion includes cylindrical pillars 702-712 and wall segments 902-910. Wall segments 902-908 are arranged horizontally (e.g., parallelly), while wall segment 910 is arranged vertically (e.g., perpendicularly) relative to the sound inlet. In this configuration, the neck of the Helmholtz resonator is defined between wall segments 906 and 910. The chamber of the Helmholtz resonator is defined by wall segments 904, 906, 910 and side walls 509, 518.

[0061] The sound inlet is narrowed by the placement of the wall segment 908 relative to the side wall 509. The arrangement also defines a non-straight path 912 with three turns for the sound to follow from the sound inlet to the sound outlet. In general, the wall portion can be configured with various wall segments to form any type of non-straight path (e.g., a spiral path, a twisted path, an S-shaped path, a sinusoidal path, a zigzag path, a serpentine path, etc.) to change the inertia of the sound channel and prevent debris from entering the sound channel.

[0062] The cylindrical support is located near the sound outlet and is vertically disposed between wall segments 902 and 906. In other examples, the cylindrical support may be located near the sound inlet. In other embodiments, other configurations of curved sound channels having one or more discrete wall portions are contemplated.

[0063] Fig.11 and Fig.12 Another embodiment of the microphone assembly 100 is illustrated, wherein: Fig.11 The microphone assembly is shown along line AA (see Fig.12 ) in cross section. In this example, the cavity 114 is partially defined by side walls 118, 120 and wall portion 116. The wall portion is a single segment with a height less than the height of the base. This enables the wall portion to form the neck of the Helmholtz resonator. Fig.11 and Fig.12 As shown in , the chamber of the Helmholtz resonator is a single circular chamber embedded in a base. Figure 4 Differently, the chamber does not cover the entire base. As desired, in other embodiments, chambers of other shapes (eg, rectangular, oval, etc.) are contemplated.

[0064] Employing a Helmholtz resonator near the entry port of a microphone or another sensor can be used to tune the resonant response of the device, thereby improving the quality of the output signal, among other advantages. Other benefits will be recognized by one of ordinary skill in the art.

[0065] While the present disclosure has been described in a manner that establishes ownership by the inventors and enables one of ordinary skill in the art to make and use the disclosure, and what is presently believed to be the best mode thereof, it should be understood and appreciated that there are many equivalents to the exemplary embodiments disclosed herein, and that numerous modifications and variations may be made thereto without departing from the scope and spirit of the present disclosure, which will be governed not by the exemplary embodiments but by the claims that follow.

Claims

1. A sensor assembly, comprising: a housing having an external device interface and a sound port leading to an interior of the housing; a transducer disposed within the housing and acoustically coupled to the acoustic port; an electrical circuit disposed within the housing and electrically coupled to the transducer and to electrical contacts on the external device interface; as well as a cavity formed in a portion of the sensor assembly and acoustically coupled to an interior of the housing through the acoustic port, The cavity has a wall portion configured to change an acoustic characteristic of the sensor assembly.

2. The sensor assembly according to claim 1, wherein: The housing includes a base having the external device interface and the sound port, and wherein the cavity and the wall portion are formed in the base.

3. The sensor assembly according to claim 2, wherein: The cavity and the wall portion form a Helmholtz resonator including a neck connected to one or more chambers.

4. The sensor assembly according to claim 3, wherein: The sound port is acoustically coupled to the one or more chambers of the Helmholtz resonator through the neck.

5. The sensor assembly according to claim 4, wherein: The neck of the Helmholtz resonator and the one or more chambers are formed in or on a same layer of the base.

6. The sensor assembly according to claim 4, wherein: The neck of the Helmholtz resonator and the one or more cavities are formed in or on different layers of the base, wherein the neck is formed in or on a first layer and the one or more cavities are formed in or on a second, different layer.

7. The sensor assembly according to claim 1, further comprising a sound port adapter having a sound channel, the sound channel having a sound inlet and a sound outlet, the sound outlet being on a mounting surface of the sound port adapter, the sound port adapter being mounted above the sound port of the housing so that the sound outlet of the sound port adapter is acoustically coupled to the sound port, wherein The cavity and the wall portion are formed in the sound port adapter.

8. The sensor assembly according to claim 7, wherein: The acoustic channel of the sound port adapter is acoustically coupled to the cavity.

9. The sensor assembly according to claim 1, wherein: The acoustic properties of the sensor assembly include any one or more of inertia, acoustic resistance, compliance, and resonance.

10. A microphone assembly, comprising: a housing having a surface mountable external device interface and an acoustic port leading to an interior of the housing; an electroacoustic transducer disposed within the interior of the housing and acoustically coupled to the acoustic port; an electrical circuit disposed within the interior of the housing and electrically coupled to the electroacoustic transducer and to electrical contacts on the external device interface; as well as a cavity formed in a portion of the microphone assembly and acoustically coupled to an interior of the housing via the acoustic port, The cavity has a wall portion configured to alter an acoustic characteristic of the microphone assembly.

11. The microphone assembly according to claim 10, wherein: The cavity and the wall portion form a Helmholtz resonator including a neck connected to one or more chambers.

12. The microphone assembly of claim 11, wherein: The housing includes a base having the surface mountable external device interface and the sound port, and wherein the Helmholtz resonator is formed in the base.

13. The microphone assembly of claim 12, wherein: The sound port is acoustically coupled to the one or more chambers of the Helmholtz resonator via the neck.

14. The microphone assembly of claim 13, wherein: The neck of the Helmholtz resonator and the one or more cavities are formed in or on different layers of the base, wherein the neck is formed in or on a first layer and the one or more cavities are formed in or on a second, different layer.

15. The microphone assembly according to claim 11, further comprising a sound port adapter having a sound channel, the sound channel having a sound inlet and a sound outlet, the sound outlet being on a mounting surface of the sound port adapter, the sound port adapter being mounted above the sound port of the housing so that the sound outlet of the sound port adapter is acoustically coupled to the sound port, wherein The Helmholtz resonator is formed in the sound port adapter.

16. The microphone assembly of claim 15, wherein: The sound inlet is located on a surface of the sound port adapter that is different from the mounting surface.

17. The microphone assembly of claim 10, wherein: The acoustic properties of the microphone assembly include any one or more of inertia, acoustic resistance, compliance, and resonance.

18. A sound port adapter for a microphone assembly including a sound transducer disposed in a housing having a sound port on a top or bottom surface of the housing, the sound port adapter comprising: a body member having a mounting surface configured to be mounted on the housing on the microphone assembly; a sound channel disposed through the body member, the sound channel having a sound inlet and a sound outlet, the sound outlet being disposed on the mounting surface of the body member; as well as A Helmholtz resonator is disposed in the body member, the Helmholtz resonator comprising a neck and one or more chambers, the acoustic channel being acoustically coupled to the one or more chambers through the neck.

19. The sound port adapter of claim 18, wherein: The Helmholtz resonator changes any one or more of the resonant frequency and amplitude of sound propagating through the acoustic channel of the sound port adapter.

20. The sound port adapter of claim 18, wherein: The sound port adapter includes a wall portion configured to form a non-straight acoustic path in the acoustic channel.

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