Acoustic sensor devices with offset transducers

Abstract

A device includes a first sound port, a second sound port connected with the first sound port via an acoustic channel. A transducer is disposed in the acoustic channel such that a first channel portion of the acoustic channel couples a first side of the transducer to an ambient environment via the first sound port and a second channel portion of the acoustic channel couples a second side of the transducer to the ambient environment via the second sound port. A first acoustic channel length of the first channel portion of the acoustic channel between the first sound port and the transducer differs from a second acoustic channel length of the second channel portion of the acoustic channel between the second sound port and the transducer by an offset. The offset is greater than a thickness of the transducer.

Description

ACOUSTIC SENSOR DEVICES WITH OFFSET TRANSDUCERSCROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. provisional application entitled “Offset Microphone,” filed July 27, 2023, and assigned Serial No. 63 / 529,242, the entire disclosure of which is hereby expressly incorporated by reference.BACKGROUND OF THE DISCLOSUREField of the Disclosure

[0002] The disclosure relates generally to directional acoustic sensor devices.Brief Description of Related Technology

[0003] A directional acoustic sensor device (e.g., a directional microphone) typically includes two sound ports that are coupled to the ambient air upon integration of the directional acoustic sensor device into a module (e.g., a microphone module) or an end product device (e.g., a webcam or a laptop). Such integration often results in long acoustic channels that connect the sound ports of the acoustic sensor device to corresponding sound ports provided in the module or the end product. The long acoustic channels often resonate in the audio band. As the length of the acoustic channel increases, the resonance frequency undesirably decreases. Such resonances often compromise the directionality of the integrated acoustic sensor device.SUMMARY OF THE DISCLOSURE

[0004] In accordance with one aspect of the disclosure, a device includes a first sound port, a second sound port connected with the first sound port via an acoustic channel, and a transducer disposed in the acoustic channel such that i) a first channel portion of the acoustic channel couples a first side of the transducer to an ambient environment via the first sound port and ii) a second channel portion of the acoustic channel couples a second side of the transducer to the ambient environment via the second sound port. A first acoustic channel length of the first channel portion of the acoustic channel between the first sound port and the transducer differs from a second acoustic channel length of the second channelportion of the acoustic channel between the second sound port and the transducer by an offset. The offset is greater than a thickness of the transducer.

[0005] In accordance with another aspect of the disclosure, a device includes a first sound port, a second sound port connected with the first sound port via an acoustic channel, and an acoustic sensor device comprising a package and a transducer housed in the package, the transducer being disposed in the acoustic channel such that i) a first channel portion of the acoustic channel couples a first side of the transducer to an ambient environment via the first sound port and ii) a second channel portion of the acoustic channel couples a second side of the transducer to the ambient environment via the second sound port. A first volume of the first channel portion of the acoustic channel between the first sound port and the transducer differs from a second volume of a second channel portion of the acoustic channel between the second sound port and the transducer by an offset volume. The offset volume is designed to reduce effects of resonance of the acoustic channel to improve directionality exhibited by the acoustic sensor device with respect to sound waves traveling in the ambient environment.

[0006] In accordance with yet another aspect of the disclosure, a device includes a first sound port, a second sound port connected with the first sound port via an acoustic channel, and a transducer disposed in the acoustic channel. The transducer is asymmetrically disposed within the acoustic channel relative to the first sound port and second sound port by an offset. The offset is greater than a thickness of the transducer.

[0007] In connection with any one of the aforementioned aspects, the devices and / or methods described herein may alternatively or additionally include or involve any combination of one or more of the following aspects or features. The transducer is housed in a package comprising a lid The package is disposed in the acoustic channel such that the first acoustic channel length of the first channel portion of the acoustic channel between the first sound port and the transducer differs from the second acoustic channel length of the second channel portion of the acoustic channel between the second sound port and the transducer by the offset. The package is disposed in the acoustic channel such that i) the lid is oriented towards the first sound port and ii) the offset positions the package such that the first acoustic channel length is less than the second acoustic channel length to position the transducer closer to the first sound port than the second sound port. The offset is greater than a thickness of an enclosed space, within the package, defined by the lid adjacent to the transducer. The offset is greater than a thickness of the package. The offset is on an order of a thickness of the package. The offset is within one order of a magnitude of a thickness ofthe package. The device further includes a gasket. The acoustic channel is formed in the gasket. The acoustic channel is arranged in one of i) a V-shaped configuration, ii) a U- shaped configuration, or iii) a straight through-hole configuration. A characteristic of a crosssection of the first channel portion of the acoustic channel between the first sound port and the transducer is different from the characteristic of a cross-section of the second channel portion of the acoustic channel between the second sound port and the transducer. The characteristic is one or both of a diameter of the cross-section and a shape of the crosssection. The offset is within a range of about 1 millimeter to 2.5 millimeters. The device further comprises a device housing in which the first sound port and the second sound port are defined. The package comprises a lid on a side of the package closer to the first sound port that the first sound port. The offset volume positions the transducer closer to the first sound port than the second sound port. The device further includes a device housing in which the first sound port and the second sound port are defined and a gasket disposed between the device housing and the acoustic sensor device, wherein the acoustic channel is formed in the gasket. The device further includes a package in which the transducer is housed. The package comprises a lid on a side of the package closer to the first sound port that the second sound port, and the offset positions the transducer closer to the first sound port than the second sound port. The offset is greater than a thickness of an enclosed space, within the package, defined by the lid adjacent to the transducer.BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0008] For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawing figures, in which like reference numerals identify like elements in the figures.

[0009] Figure 1 is a cross-sectional view of a device equipped with an acoustic sensor device 102 asymmetrically integrated into the device with an offset to avoid adverse resonance effects in accordance with one example.

[0010] Figure 2 is a graphical plot of directivity index for an example device having an offset acoustic sensor device.

[0011] Figure 3 depicts a cross-sectional view of a device equipped with an acoustic sensor device with a distance-based offset to avoid adverse resonance effects in accordance with an example.

[0012] Figure 4 depicts a cross-sectional view of a device equipped with an acoustic sensor device with a volume-based offset to avoid adverse resonance effects in accordance with an example.

[0013] Figure 5 is a cross-sectional, schematic view of an acoustic sensor device, according to an example.

[0014] The embodiments of the disclosed devices may assume various forms. Specific embodiments are illustrated in the drawing and hereafter described with the understanding that the disclosure is intended to be illustrative. The disclosure is not intended to limit the invention to the specific embodiments described and illustrated herein.DETAILED DESCRIPTION OF THE DISCLOSURE

[0015] Devices equipped with asymmetrically disposed transducers (or acoustic sensor devices, such as microphones, that includes the transducers) are described. In an example, an acoustic channel may be disposed between two sound ports of a device and may be provided to expose opposing sides of the transducer to an ambient environment via the sound ports of the device. For example, the transducer may be disposed in the acoustic channel such that a first portion of the acoustic channel exposes a first side of the transducer to an ambient environment via the first sound port and a second portion of the acoustic channel couples a second, opposing, side of the transducer to the ambient environment via the second sound port. The transducer may thus sense a pressure gradient between the opposing sides of the transducer created by sound waves travelling in the ambient environment. The transducer may be asymmetrical disposed in the acoustic channel such that the first portion of the acoustic channel differs from the second portion of the acoustic channel. For example, as described in more detail below, the first portion and the second portion of the acoustic channel may differ in length and / or volume by an offset to provide asymmetry, in various examples.

[0016] Accordingly, the asymmetry may constitute, and / or be characterized as or realized in, an offset in two acoustic channel lengths and / or an offset volume. For instance, the asymmetry may be an offset in two acoustic channel lengths of an acoustic channel configured to couple the transducer to an ambient environment. Alternatively or additionally, the asymmetry may be an offset volume between the volumes of the channel.

[0017] The asymmetrical disposition of the transducer (or an acoustic sensor device, such as a microphone, that includes the transducer) leads to unexpected benefits. Theasymmetry runs counter to the notion that the transducer, or the acoustic sensor device that includes the transducer, is placed perfectly in the middle of the acoustic channel (e.g., to maintain symmetry on each side). Offsetting the transducer (or the acoustic sensor device that includes the transducer) from a centered position reduces the impact of resonance (e.g., resonance of the acoustic channel). As a result, the acoustic sensor device achieves better directionality than expected. For example, the acoustic sensor device may achieve better directionality than an acoustic sensor device that is positioned in an acoustic channel without an offset.

[0018] The asymmetrically disposed transducers or acoustic sensor devices (e.g., microphones) may be integrated into, and / or otherwise useful in connection with a wide variety of products (e.g., product devices). For instance, the asymmetry may be applied to various types of product devices having an internal microphone coupled to lengthy acoustic channels. Examples include webcams, laptops, conference phones, soundbars, and VR headsets.

[0019] Although generally described in connection with microphones, the disclosed asymmetrical acoustic channel configurations may be used in other applications and contexts. For instance, the disclosed asymmetrical acoustic channel configurations are useful in connection with accelerometers, gyroscopes, inertial sensors, pressure sensors, gas sensors, etc. The disclosed asymmetrical acoustic channel configurations are described in the context of excitation by sound waves. However, alternative or additional stimuli may excite the asymmetrically disposed transducers or sensor devices in other contexts.

[0020] Figure 1 depicts a device 100 equipped with an acoustic sensor device 102 asymmetrically integrated into the device 100 with an offset to avoid adverse resonance effects in accordance with one example. Only a portion of the device 100 is shown for ease of illustration. The acoustic sensor device 102 may be a microphone, for example. The device 100 may be or include any product device, such as a webcam. In another example, the device 100 may be a stand-alone module or a module that may be configured for integration into an end product device, such as a webcam. The acoustic sensor device 102 may be configured as a directional acoustic sensor device (e.g., a directional microphone) having two sound ports. The acoustic sensor device 102 may thus be configured to exhibit a directional response or pick-up pattern, such as a dipole or “figure 8” pattern, with respect to sound waves traveling in the ambient environment. In other examples, the acoustic sensor device 102 may be configured to exhibit a directional response or pick-up pattern different from a dipole pattern, such as a cardioid pattern or another suitable directional pattern. Anexample acoustic sensor device that may correspond to the acoustic sensor device 102 is described in more detail below with reference to Figure 5. In other examples, the acoustic sensor device 102 may be different from the acoustic sensor device of Figure 5.

[0021] The device 100 includes a gasket 104 in which an acoustic channel 116 is defined. The device 100 also includes a device housing 106 in which a first sound port 120 and a second sound port 124 are defined. For instance, the device housing 106 may include a wall, side, or other structure adjacent to the gasket 104. The gasket 104 is thus disposed between the device housing 106 and the acoustic sensor device 102. The acoustic channel 116 connects or couples the first sound port 120 to the second sound port 124. In an example, the gasket 104 defines a pair of tubes. The tubes are arranged to define a bent acoustic channel 116 that allows the first sound port 120 and the second sound port 124 to be disposed on a same surface of the device 100. For example, the acoustic channel 116 may be V-shaped or a U-shaped channel.

[0022] The acoustic sensor device 102 includes a transducer 108 supported by a substrate, such as a printed circuit board (PCB), 110 and protected by a lid 112. The acoustic sensor device 102 also includes an application-specific integrated circuit (ASIC) that is not shown in Figure 1 for ease of illustration. The ASIC is used to amplify the signal generated by the transducer 108. The acoustic sensor device 102 also includes two sound ports (not shown in Figure 1) including a first sound port that may be embedded in the lid 112 and a second sound port that may be embedded in the PCB 110. The acoustic sensor device 102 may be supported by a substrate or product PCB 114. In some examples, the substrate or product PCB 114 is used to transfer the signal from the acoustic sensor device 102 to other components in the device 100.

[0023] The acoustic channel 116 includes a first channel portion 118 and a second channel portion 122. The first channel portion 118 is a lid-side channel portion that couples the first sound port 120 in the device 100 to the first sound port embedded in the lid 112 of the acoustic sensor device 102. The second channel portion 122 is a PCB-side channel portion that couples the second sound port 124 of the device 100 to the second sound port embedded in the PCB 110 of the acoustic sensor device 102.

[0024] As shown in Figure 1 , the acoustic sensor device 102 and the transducer 108 are offset from a center point of the acoustic channel 116. The center point of the acoustic channel 116 may be defined as the position in the acoustic channel 116 in which the length and / or the volume of the first channel portion 118 and the second channel portion 122 are equal. The offset may comprise an offset specifically designed to reduce effects ofresonance of the acoustic channel on the directionality exhibited by the acoustic sensor device with respect to sound waves traveling in the ambient environment. In an example, the offset is greater than an unintentional offset due to, for instance, a manufacturing tolerance. In some examples, the acoustic sensor device 102 is offset such that the length of the first (lid-side) channel portion 118 is shorter than the second (PCB-side) channel portion 122. In some cases, the acoustic sensor device 102 is offset by at least about 1 millimeter (mm) but less than 2.5 mm relative to the center point of the acoustic channel 116. In an example, the offset may be greater than a thickness 126 of the transducer 108. The thickness 126 of the transducer 108 may correspond to a thickness of a substrate (e.g., a silicone die substrate) in which the transducer 108 is formed. In some examples, the thickness 126 of the transducer 108 is less than 1mm. In an example, the thickness 126 of the transducer 108 is about 500 micrometers (pm). In some examples, the offset may be greater than a thickness of a diaphragm of the transducer 108 and less than a thickness of a substrate (e.g., a silicone die substrate) in which the transducer 108 is formed. For example, the transducer 108 may be a MEMS transducer formed in a silicone die having a thickness in a range of about 300 pm to 600 pm, for example. The MEMS transducer may include a MEMS diaphragm having a thickness of, for example, less than 10 pm. The offset may be greater than the thickness of the MEMS diaphragm (e.g., greater than 10 pm) and less than the thickness of the silicone die (e.g., less than 300 pm - 600 pm) in which the MEMS transducer is formed.

[0025] Alternatively or additionally, the offset may be greater than a thickness 128 of the acoustic sensor device 102 (e.g., greater thickness of a package of the acoustic sensor device 102) which may include the thickness of the lid 112 and thickness of the PCB 110. In some examples, the thickness of the acoustic sensor device 102 may be in the range between 0.6 mm and 1 .5 mm.

[0026] It can be thought that the volume of air inside the package of the acoustic sensor device 102 creates a type of asymmetry within the acoustic channel 116. Accordingly, offsetting the position of the acoustic sensor device 102 may counteract the adverse effects of the package of the acoustic sensor device 102, balancing both sides of the acoustic channels around the transducer 108.

[0027] The offset with which the acoustic sensor device 102 is placed relative to the center point of the acoustic channel 116 may be characterized by distance and / or volume. In terms of distance, the first channel portion 118 of the acoustic channel 116 has an acoustic channel length that is different from an acoustic length of the second channel portion 122 ofthe acoustic channel 116 by an offset length. In terms of volume, the first channel portion 118 of the acoustic channel 116 has a volume that is different from a volume of the second channel portion 122 of the acoustic channel 116 by an offset volume. In some examples, the offset volume may be similar to or greater than an enclosed space within a package of the acoustic sensor device.

[0028] The amount of the offset may vary. For instance, in some examples, the acoustic sensor device 102 is offset by at least about 1 mm relative to the center point. In other cases, the acoustic sensor device 102 is offset by at least about 2.5 mm relative to the center point of the acoustic channel 116. In an example, the acoustic sensor device 102 is offset by an offset in a range between 1 mm and 2.5 mm relative to the center point. Alternatively or additionally, the offset is greater than a thickness of an enclosed space defined by the lid 112 of the acoustic sensor device 102 adjacent to the transducer 108.

[0029] In some cases, the offset is in the direction on a side of the acoustic sensor device 102 having the lid 112. Thus, if the acoustic sensor device 102 is oriented such that the lid 112 is disposed on the side closer to a first sound port (e.g., the sound port 120, as illustrated in Figure 1), the offset may be in the direction of the side of the acoustic sensor device 102 closer to the first sound port 120 than to the second sound port 124. Accordingly, in this case, the length of the first channel portion 118 may be less than the length of the second channel portion 122, in an embodiment.

[0030] In some examples, the offset is on the order of the thickness 128 of the package of the acoustic sensor device 102. For example, the package of the acoustic sensor device 102 may have a thickness in the range between 0.6 mm and 1 .5 mm, and the offset may be greater than the thickness the package of the acoustic sensor device 102 and less than about twice the thickness of the package of the acoustic sensor device 102. In another example, the offset may be within one order of magnitude of the thickness 128 of the package of the acoustic sensor device 102. For example, the package of the acoustic sensor device 102 may have a thickness of about 0.5 mm or 0.6 mm, and the offset may be greater than the thickness the package of the acoustic sensor device 102 and less than about 4 mm. As just an example, the package of the acoustic sensor device 102 may have a thickness of about 0.5 mm or 0.6 mm, and the offset may be about 2 mm or 3 mm. The thickness 128 of the acoustic sensor device 102 may refer to the dimension of the package of the acoustic sensor device 102 in the direction of sound travel through the acoustic channel 116.

[0031] In some examples, the offset is not greater than about 3 mm. In some examples, the offset is not greater than about six times the thickness 128 of the package of the acoustic sensor device 102. As just an example, the package of the acoustic sensor device 102 may have a thickness of about 0.5 mm or 0.6 mm, and the offset may be about four, five or six times the thickness of the package of the of the acoustic sensor device 102.

[0032] In some examples, the configuration of the acoustic channel 116 may vary in alternative or additional ways. For instance, a characteristic of a cross-section of the acoustic channel 116 on one side of the acoustic sensor device 102 may differ from the characteristic of a cross-section of the acoustic channel 116 on the other side of the acoustic sensor device 102. Thus, for example, a characteristic (e.g., a size, a diameter, a shape, etc.) of a cross-section of the first portion 118 of the acoustic channel 116 may differ from the characteristic (e.g., a size, a diameter, a shape, etc.) of a cross-section of the second portion 122 of the acoustic channel 116. The characteristic may include one or more of a size, a diameter, and a shape, for example.

[0033] Figure 2 is a graphical plot 200 depicting the directivity index (DI) as a function of frequency for example acoustic sensor devices (e.g., microphones) disposed in a V-shaped gasket channel, such as the acoustic channel 116 formed in the gasket 104, with and without an offset. As shown in Figure 2, in the illustrated example, the average directivity index (Dl) of the acoustic sensor device from 20Hz to 20kHz, with or without the offset, is 4.6 dB. Curve 202 shows the directivity index for the centered acoustic sensor device within the acoustic channel, without any offset. As shown, the directivity index dips at about 10kHz, which means directionality is lost. Generally, a value of OdB is indicative of an omnidirectional microphone and a value of 4.8dB is an ideal dipole microphone. Curve 204 shows the directivity index for an acoustic sensor device offset by about 1 mm to 2 mm. The dip in directionality is mitigated and, as a result, the acoustic sensor device maintains better directionality around 10kHz.

[0034] Although the acoustic sensor device 100 is described in connection with product devices having sound ports located on the same surface of the end product (rather than, e.g., on opposing sides), the location of the sound ports and / or other aspects of the configuration of the disclosed devices may vary. Thus, the shape and / or other aspects of the channel may vary accordingly. For instance, the disclosed devices are not limited to configurations in which the acoustic sensor device is coupled to a V-shaped channel or other configurations that use bent tubes to connect the sound ports of the acoustic sensor device to a same surface of the device into which the acoustic sensor device is integrated.

[0035] Figure 3 depicts a cross-sectional view of a device 300 equipped with an acoustic sensor device 302 with a distance-based offset to avoid adverse resonance effects in accordance with an example. The device 300 is similar to the device 100 of Figure 1 and includes like-numbered elements with the device 100 of Figure 1 that are not described in detail below for the purpose of brevity. The acoustic sensor device 302 includes a transducer (e.g., a MEMS transducer) 308 mounted on or otherwise supported by a substrate (e.g., a PCB) 310. The acoustic sensor device 302 also includes a lid 312 that may be attached to the substrate 310 and may encapsulate the transducer 308. The substrate 310 and the lid 312 may form a package of the acoustic sensor device 302. The acoustic sensor device 302 also includes a first sound port (not illustrated in Figure 3) that may be embedded in the lid 312 and a second sound port (not shown in Figure 3) that may be embedded in the substrate 310.

[0036] The acoustic sensor device 302 is embedded within a gasket 304. Unlike gasket 104 which assumes a bent (e.g., arranged in a “V” shape or a “U” shape), gasket 304 uses a thru hole configuration. An acoustic channel 316 is formed in the gasket 304. The acoustic channel 316 includes a first channel portion 318 and a second channel portion 322. The first channel portion 318 of the acoustic channel 316 is a lid-side channel portion that couples a first sound port 320 in the device 300 to the top side of a transducer 308 of the acoustic sensor device 302 via the first sound port embedded in the lid 312 of the acoustic sensor device 302. The second channel portion 322 is a PCB-side channel portion that couples a second sound port 324 in the device 300 to the bottom side of the transducer 308 of acoustic sensor device 302. The first channel portion 318 and the second channel portion 322 may be configured in various manners described above with respect to the first channel portion 118 and the second channel portion 122 to provide an offset of the transducer 308 from a center of the acoustic channel 316, in various examples. The acoustic sensor device 302 may be placed in the acoustic channel 316 such that the first channel portion 318 has an acoustic length different from an acoustic length of the second channel portion 324. For example, as illustrated in Figure 3, the acoustic sensor device 302 may be placed in the acoustic channel 316 with an offset such that the length of the lid-side channel portion 318 is shorter than the length of the PCB-side channel portion 322.

[0037] Figure 4 depicts a cross-sectional view of a device 400 that may be an alternative embodiment of the device 300 of Figure 3. Device 400 includes an acoustic sensor device 402 embedded within an acoustic channel 416 formed in a gasket 404. The acoustic channel 416 may be arranged to provide a volume-based offset to avoid adverse resonance effects.The acoustic sensor device 402 includes a transducer (e.g., a MEMS transducer) 408 mounted on or otherwise supported by a substrate (e.g., a PCB) 410. The acoustic sensor device 402 also includes a lid 412 that may be attached to the substrate 410 and may encapsulate the transducer 408. The substrate 410 and the lid 412 may form a package of the acoustic sensor device 402. The acoustic sensor device 402 also includes a first sound port (not illustrated in Figure 4) that may be embedded in the lid 412 and a second sound port (not shown in Figure 4) that may be embedded in the substrate 410.

[0038] The acoustic channel 416 includes a first channel portion 418 and a second channel portion 422. The first channel portion 418 of the acoustic channel 416 is a lid-side channel portion that couples a first sound port 420 in the device 400 to the top side of a transducer 408 of the acoustic sensor device 402 via the first sound port embedded in the lid 412 of the acoustic sensor device 402. The second channel portion 422 is a PCB-side channel portion that couples a second sound port 424 in the device 400 to the bottom side of the transducer 408 of the acoustic sensor device 402. In the example illustrated in Figure 4, the length of the lid-side channel portion 418 is equal to the length of the PCB-side channel portion 422. However, the lid-side channel portion 418 is modified relative to the channel portion 418 of Figure 3 such that the lid-side channel portion 418 has a smaller diameter relative to the PCB-side channel portion 422 and thus smaller volume of air that the PCB-side channel portion 422. This volume-based offset may counteract asymmetry introduced by the package of the acoustic sensor device 402 and balance the two acoustic channels on the opposing sides of the transducer 408.

[0039] Figure 5 is a cross-sectional, schematic view of an acoustic sensor device 502, according to an example. The acoustic sensor device 502 may be a microphone, for example. In various examples, the acoustic sensor device 500 corresponds to the acoustic sensor devices described above, such as the acoustic sensor device 102 described above with reference to Figure 1 , acoustic sensor device 302 described above with reference to Figure 3, and acoustic sensor device 402 described above with reference to Figure 4. The acoustic sensor device 502 includes like-numbered elements that may be the same as or similar to the corresponding elements of the acoustic sensor devices 102, 302, 402. In other examples, however, the acoustic sensor devices 102, 302, 402 may be different from the acoustic sensor device 502.

[0040] The acoustic sensor device 502 includes a transducer 508. The transducer 508 may be a MEMS transducer, for example. In other examples, the transducer 508 may comprise a suitable transducer other than a MEMS transducer. The transducer 508 may beattached to or otherwise supported by a PCB or other substrate 510 (generally referred to herein as “PCB 510”). The PCB 510 may comprise one or more layers. In an example in which the PCB 510 comprises multiple layers, respective ones of the multiple layers may be separated from one another by a dielectric material. The one or more layers of the PCB 510 may include conductive traces that may route electrical signals in the PCB 510. The acoustic sensor device 502 may also include a lid or other enclosure 512 (generally referred to herein as “lid 512”). The lid 512 may be placed over the PCB 510 to enclose the components of the acoustic sensor device 502 mounted on or otherwise attached to the PCB 510. The lid 512 may be composed of, or otherwise include, a metal, plastic, ceramic, or other material. The lid 512 and the PCB 510 may form a package of the acoustic sensor device 502. In other examples, a package of the acoustic sensor device 502 may be formed in other suitable manners.

[0041] The transducer 508 may include a sensing element 530 positioned over a cavity 542. The cavity 542 may be formed in the transducer 508 through various microfabrication practices including, for instance, deep reactive ion etching (DRIE). The sensing element 530 may comprise a diaphragm, for example. The sensing element 530 includes a first side that faces outwards with respect to the cavity 542 and a second side that faces the cavity 542. In an example, the sensing element 530 may comprise a cantilever diaphragm structure that is attached on one end and is free to move on the other end. In another example, the sensing element 530 may comprise another suitable structure, such as a fixed-fixed structure that is fixed on more than two sides, such as a diaphragm that is fixed or anchored on all sides around the perimeter.

[0042] The acoustic sensor device 502 may include a first sound port 536 formed in the lid 512 and a second sound port 538 formed in the PCB 510. A first air volume 560 may be formed in the package of the acoustic sensor device 502 between the PCB 510 and the lid 512 and may be configured to be exposed to the ambient environment via the first sound port 536. A second air volume 562 may comprise the cavity 542 in the transducer 508 and may be configured to be exposed to the ambient environment via the second sound port 538. The sensing element 530 may thus have two opposing sides exposed to the ambient environment, and may sense a pressure gradient between the opposing sides of the sensing element 530 exposed to the ambient environment. Because the sensing element 530 of the transducer 508 has two opposing sides that are exposed to the ambient environment, and thus the transducer 508 senses the pressure gradient between the opposing sides of the sensing element 530 exposed to the ambient environment, the transducer 508 may exhibit adirectional polar pattern. For example, the transducer 508 may exhibit a dipole, or figure 8, polar pattern.

[0043] The acoustic sensor device 502 may also include an ASIC 574. The ASIC 574 may be mounted on or otherwise attached to the PCB 510. The ASIC 574 may be covered by a globtop 576. The ASIC 574 may be electrically coupled to the transducer 508. For example, the transducer 508 and ASIC 574 may be electrically connected by wire bonds 578, either directly to each other, or via traces on the PCB 510. The ASIC 574 may also be electrically connected to the PCB 510 by wire bonds 580. In other examples, the transducer 508 and the ASIC 574 may be attached and / or electrically coupled using other suitable methods. For example, the transducer 508 may be attached to the PCB 510 using flip chip technology. The ASIC 574 may be configured to read out electrical signals generated by the transducer 508 based on movement of the sensing element 530 and to amplify the signals.

[0044] In various examples, the acoustic sensor device 502 may be asymmetrically integrated into an acoustic channel as described herein. For example, the acoustic sensor device 502 may be integrated into an acoustic channel that includes a first portion coupled to the sound port 536 and a second portion coupled to the sound port 538. The first acoustic portion of the acoustic channel may be disposed between the sound port 536 and a first sound port of a module or an end product device that incorporate the acoustic sensor device 502. The first acoustic portion of the acoustic channel may thus expose the air volume 560 to the ambient environment via the sound port 536 and the first sound port of the module or the end product device that incorporate the acoustic sensor device 502. The second portion of the acoustic channel may be disposed between the sound port 538 and a second sound port of the module or the end product device that incorporate the acoustic sensor device 502. The second acoustic portion of the acoustic channel may thus expose the air volume 562 to the ambient environment via the sound port 538 and the second sound port of the module or the end product device that incorporate the acoustic sensor device 502. The first portion of the acoustic channel and the second portion of the acoustic channel may be differently configured to provide asymmetry as described herein, and improve directionality of the acoustic sensor device 502, in various examples. For example, first portion of the acoustic channel and the second portion of the acoustic channel may differ in acoustic length and / or acoustic volume by an offset to provide asymmetry as described herein, and improve directionality of the acoustic sensor device 502, in various examples.

[0045] Examples are described in which an offset in acoustic sensor device (e.g., microphone) position in an acoustic channel leads to directionality at higher frequencies andmitigates the adverse effects of resonances. In turn, these unexpected benefits of the offset allow the acoustic sensor device to be used with longer acoustic channels. As a result, the acoustic sensor device may be integrated with, and disposed in, a wider variety of products and product configurations.

[0046] The offset of the disclosed devices may be useful in additional or alternative aspects of product design. For instance, the offset may lead to increased flexibility in product designs involving non-ideal acoustic sensor device locations. The offset of the disclosed devices may be useful in counterbalancing the effects of such non-ideal acoustic sensor device placements.

[0047] The term "about" is used herein in a manner to include deviations from a specified value that would be understood by one of ordinary skill in the art to effectively be the same as the specified value due to, for instance, the absence of appreciable, detectable, or otherwise effective difference in operation, outcome, characteristic, or other aspect of the disclosed methods and devices.

[0048] The present disclosure has been described with reference to specific examples that are intended to be illustrative only and not to be limiting of the disclosure. Changes, additions and / or deletions may be made to the examples without departing from the spirit and scope of the disclosure.

[0049] The foregoing description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom.

Claims

What is Claimed is:

1. A device comprising: a first sound port; a second sound port connected with the first sound port via an acoustic channel; and a transducer disposed in the acoustic channel such that i) a first channel portion of the acoustic channel couples a first side of the transducer to an ambient environment via the first sound port and ii) a second channel portion of the acoustic channel couples a second side of the transducer to the ambient environment via the second sound port; wherein: a first acoustic channel length of the first channel portion of the acoustic channel between the first sound port and the transducer differs from a second acoustic channel length of the second channel portion of the acoustic channel between the second sound port and the transducer by an offset, and the offset is greater than a thickness of the transducer.

2. The device of claim 1 , wherein: the transducer is housed in a package comprising a lid; and the package is disposed in the acoustic channel such that the first acoustic channel length of the first channel portion of the acoustic channel between the first sound port and the transducer differs from the second acoustic channel length of the second channel portion of the acoustic channel between the second sound port and the transducer by the offset.

3. The device of claim 2, wherein the package is disposed in the acoustic channel such that i) the lid is oriented towards the first sound port and ii) the offset positions the package such that the first acoustic channel length is less than the second acoustic channel length to position the transducer closer to the first sound port than the second sound port.

4. The device of claim 2, wherein the offset is greater than a thickness of an enclosed space, within the package, defined by the lid adjacent to the transducer.

5. The device of claim 2, wherein the offset is greater than a thickness of the package.

6. The device of claim 2, wherein the offset is on an order of a thickness of the package.

7. The device of claim 2, wherein the offset is within one order of a magnitude of a thickness of the package.

8. The device of claim 1 , further comprising a gasket, wherein the acoustic channel is formed in the gasket.

9. The device of claim 1 , wherein the acoustic channel is arranged in one of i) a V- shaped configuration, ii) a U-shaped configuration, or iii) a straight through-hole configuration.

10. The device of claim 1 , wherein a characteristic of a cross-section of the first channel portion of the acoustic channel between the first sound port and the transducer is different from the characteristic of a cross-section of the second channel portion of the acoustic channel between the second sound port and the transducer.11 . The device of claim 10, wherein the characteristic is one or both of a diameter of the cross-section and a shape of the cross-section.

12. The device of claim 1 , wherein the offset is within a range of about 1 millimeter to 2.5 millimeters.

13. The device of claim 1 , further comprising a device housing in which the first sound port and the second sound port are defined.

14. A device comprising: a first sound port; a second sound port connected with the first sound port via an acoustic channel; and an acoustic sensor device comprising a package and a transducer housed in the package, the transducer being disposed in the acoustic channel such that i) a first channel portion of the acoustic channel couples a first side of the transducer to an ambient environment via the first sound port and ii) a second channel portion of the acoustic channel couples a second side of the transducer to the ambient environment via the second sound port; wherein: a first volume of the first channel portion of the acoustic channel between the first sound port and the transducer differs from a second volume of a second channel portion of the acoustic channel between the second sound port and the transducer by an offset volume, and the offset volume is designed to reduce effects of resonance of the acousticchannel to improve directionality exhibited by the acoustic sensor device with respect to sound waves traveling in the ambient environment.

15. The device of claim 14, wherein: the package comprises a lid on a side of the package closer to the first sound port that the first sound port; and the offset volume positions the transducer closer to the first sound port than the second sound port.

16. The device of claim 14, further comprising: a device housing in which the first sound port and the second sound port are defined; and a gasket disposed between the device housing and the acoustic sensor device, wherein the acoustic channel is formed in the gasket.

17. The device of claim 14, wherein the acoustic channel is arranged in one of i) a V- shaped configuration, ii) a U-shaped configuration, or iii) a straight through-hole configuration .

18. The device of claim 14, wherein a characteristic of a cross-section of the first channel portion of the acoustic channel between the first sound port and the transducer is different from the characteristic of a cross-section of the second channel portion of the acoustic channel between the second sound port and the transducer.

19. A device comprising: a first sound port; a second sound port connected with the first sound port via an acoustic channel; and a transducer disposed in the acoustic channel; wherein: the transducer is asymmetrically disposed within the acoustic channel relative to the first sound port and second sound port by an offset, and the offset is greater than a thickness of the transducer.

20. The device of claim 19, further comprising a package in which the transducer is housed, wherein: the package comprises a lid on a side of the package closer to the first sound port that the second sound port; andthe offset positions the transducer closer to the first sound port than the second sound port.21 . The device of claim 19, further comprising a package in which the transducer is housed, wherein: the package comprises a lid; and the offset is greater than a thickness of an enclosed space, within the package, defined by the lid adjacent to the transducer.

22. The device of claim 19, further comprising: a device housing in which the first sound port and the second sound port are defined; and a gasket disposed within the device housing, wherein the acoustic channel is formed in the gasket.

23. The device of claim 19, further comprising a package in which the transducer is housed, wherein the offset is greater than a thickness of the package.

24. The device of claim 23, wherein the offset is on an order of the thickness of the package.

25. The device of claim 23, wherein the offset is within one order of magnitude of the thickness of the package.

Images