Techniques for reducing wind noise

Abstract

Certain aspects of the present disclosure provide an apparatus. The apparatus includes a support structure including at least one microphone sensor, and a first material layer disposed adjacent to the support structure, wherein a first air layer is formed between the first material layer and the support structure, the first air layer being adjacent to the microphone sensor. In certain aspects, multiple material layers can be used, each material layer forming an air layer. For example, the apparatus can further include a second material layer disposed adjacent to the first material layer, wherein a second air layer is formed between the first material layer and the second material layer.

Description

Background Technology

[0001] This disclosure relates in general to microphone equipment.

[0002] Headphones and speakers may include any number of microphones. Microphones can be used for, but are not limited to, one or more synchronous or asynchronous applications such as active noise cancellation, noise reduction, and / or communication. Microphones can be used in a variety of environments that may affect the user experience. For example, in harsh environments, microphones should be waterproof, sweatproof, dustproof, etc. Also, in windy conditions, wind noise may degrade the quality of the audio signal sensed by the microphone. Therefore, it is necessary to improve the signal-to-wind noise ratio of the microphone. Summary of the Invention

[0003] All examples and features mentioned in this article can be combined in any technically possible way.

[0004] A specific aspect of this disclosure provides an apparatus. The apparatus includes a support structure comprising at least one microphone sensor, and a first material layer disposed adjacent to the support structure, wherein a first air layer is formed between the first material layer and the support structure, the first air layer being adjacent to the microphone sensor.

[0005] In one aspect, the support structure includes a housing having a cavity in which the at least one microphone sensor is located, and wherein the first material layer is adjacent to an opening in the cavity. In another aspect, the first material layer includes a screen of acoustically resistive material.

[0006] In certain aspects, the first material layer includes a membrane. In certain aspects, the membrane is at least one of waterproof or dustproof.

[0007] In a particular aspect, the device further includes a second material layer disposed adjacent to the first material layer, wherein a second air layer is formed between the first material layer and the second material layer. In a particular aspect, the device further includes a third material layer disposed adjacent to the second material layer, wherein a third air layer is formed between the second material layer and the third material layer. In a particular aspect, each of the first material layer, the second material layer, and the third material layer comprises a film or layer of acoustically resistive material.

[0008] In one aspect, the at least one microphone sensor includes a high-impedance microphone sensor. In another aspect, the high-impedance microphone sensor includes a microelectromechanical system (MEMS) microphone sensor.

[0009] A specific aspect of this disclosure provides a method for sensing an audio signal. The method typically includes sensing the audio signal via at least one microphone sensor supported by a support structure, receiving the audio signal via a first material layer positioned adjacent to the microphone sensor, wherein a first air layer is formed between the first material layer and the support structure, the first air layer being adjacent to the support structure, and generating an electrical signal based on the audio signal via the microphone sensor.

[0010] In one aspect, the support structure includes a housing having a cavity in which the at least one microphone sensor is located, and wherein the first material layer is adjacent to an opening in the cavity. In another aspect, the first material layer includes a screen of acoustically resistive material.

[0011] In certain aspects, the first material layer includes a membrane. In certain aspects, the membrane is at least one of waterproof or dustproof.

[0012] In one aspect, the audio signal is received via a second material layer positioned adjacent to the first material layer, wherein a second air layer is formed between the first and second material layers. In another aspect, the audio signal is received via a third material layer positioned adjacent to the second material layer, wherein a third air layer is formed between the second and third material layers. In another aspect, each of the first, second, and third material layers comprises a film or layer of acoustically resistive material.

[0013] In one aspect, the at least one microphone sensor includes a high-impedance microphone sensor. In another aspect, the high-impedance microphone sensor includes a MEMS microphone sensor. Attached Figure Description

[0014] Figure 1 An exemplary earpiece cover for a headset receiver is shown.

[0015] Figure 2 The internal portion of the headphones is shown after the headphone cover has been removed.

[0016] Figure 3 An example of a top microphone element is shown.

[0017] Figure 4 An exemplary microelectromechanical system (MEMS) microphone according to a specific aspect of this disclosure is shown.

[0018] Figure 5 It is a graph showing the attenuation of audio signals and wind noise according to a specific aspect of this disclosure.

[0019] Figure 6An exemplary MEMS microphone, implemented according to a specific aspect of this disclosure, is shown through multiple material layers having acoustic resistivity.

[0020] Figure 7A and Figure 7B The graph shows the improvement in signal-to-noise ratio (SNR) of a MEMS microphone implemented using multiple material layers according to a specific aspect of this disclosure.

[0021] Figure 8 An exemplary MEMS microphone with a material layer implemented using a membrane is shown according to a specific aspect of this disclosure.

[0022] Figure 9 An exemplary MEMS microphone having a membrane and material layer is shown according to a specific aspect of this disclosure.

[0023] Figure 10 A flowchart illustrating an exemplary operation for sensing an audio signal according to a specific aspect of this disclosure is shown. Detailed Implementation

[0024] Specific aspects of this disclosure provide techniques for reducing flow noise on microphones or other pressure transducers that may be caused by wind or other airborne local pressure fluctuations. As described in more detail below, the techniques described herein are effective for any high-impedance microphone or pressure transducer. For example, the techniques described herein may be effective for any microphone in which the total impedance of the microphone (e.g., diaphragm, port, and front cavity) is significantly higher than the total impedance of the wind noise treatment system described herein. An example of a high-impedance microphone is a microelectromechanical system (MEMS) microphone.

[0025] While the specific examples provided herein describe techniques for reducing flow noise in MEMS microphones for ease of understanding, the aspects described herein can be implemented in any suitable microphone. The aspects of this disclosure can be applied to reduce flow noise in a variety of microphone systems, such as wearable microphone devices with various form factors. These form factors include, but are not limited to, audio glasses, hearing aids, and other head-mounted, shoulder-mounted, or body-worn audio devices that include one or more acoustic drivers to generate sound (whether or not in contact with the user's ear).

[0026] Figure 1 An exemplary earphone cover 100 for a headset is shown. The earphone cover 100 includes a set of perforations 102, 104 located in two positions. Each of the perforation sets 102 and 104 on the earphone cover 100 is associated with a separate microphone element opening visible to the outside world. Although two sets of perforations are shown, the earphone cover may include more or fewer than two sets of perforations. Figure 1It is not shown in the diagram, but one or more openings may exist behind the perforation leading to the microphone element.

[0027] Figure 2 It shows how to remove the headphone cover, such as Figure 1 The image shows the internal portion of the earphone 200 behind the earphone cover 100. It shows two housings 202 and 204. Each housing defines a corresponding (first) cavity. The cavity of the housing is coupled to a corresponding microphone element (not shown). The microphone element includes a microphone sensor disposed within the microphone cavity. According to a particular aspect of this disclosure, as described in more detail herein, one or more material layers may be implemented to reduce flow noise and protect the microphone sensor from water and dust ingress. In some cases, one or more material layers may be disposed at the outer ends of each housing 202 and housing 204.

[0028] A microphone sensor can be housed within a microphone element (which may be referred to as a microphone assembly). The microphone element housing the microphone sensor may have a sound opening that extends through a top cover (referred to as a top microphone element) or through a bottom substrate (referred to as a bottom microphone element). In one aspect, the bottom surface of the microphone element is a substrate, a printed circuit board (PBC), or a flexible circuit board. It should be noted that the aspects described herein are not limited to top microphone elements and can also be implemented in both top and bottom MEMS microphone elements.

[0029] Figure 3 An example of a top microphone element 300 is shown. A sound opening 302 extends through a top cover or cap 304 of the microphone element. A microphone sensor 306 is located within the microphone element 300. If the microphone sensor 306 is a MEMS device, it is coupled to an application-specific integrated circuit (ASIC) 308. The microphone sensor 306 and the ASIC 308 are disposed on a substrate 310, such as a PCB substrate or a flexible circuit board. In one aspect, the flexible circuit board does not contain wires (leads). The microphone sensor 306 is located within a microphone cavity 312 defined by the cap 304 and the substrate 310.

[0030] Specific aspects of this disclosure provide techniques for reducing wind noise in a microphone with minimal impact on the quality of the audio signal sensed by the microphone. In windy environments, it is important to reduce wind noise without compromising audio signal quality, thereby improving the user experience. These specific aspects of the disclosure can be applied to microphones with relatively small cavities, achieved by forming a material layer (e.g., a membrane or any acoustically resistive layer) over the cavity and forming a thin air layer between the material layer and a support structure (e.g., a housing) of the cavity containing the microphone sensor. In some examples, the air layer can be as thin as 100 micrometers or less, although in other examples, the thickness of the air layer can be greater than 100 micrometers.

[0031] Figure 4 An exemplary MEMS microphone 400 according to a specific aspect of this disclosure is illustrated. As shown, the MEMS microphone 400 may include a cavity 408 and a microphone sensor disposed within the cavity 408 (e.g., as per [reference]). Figure 3 The support structure (e.g., housing 406) described herein. A material layer 402 having acoustic resistivity (such as a resistive mesh or microperforated plate) may be configured to be adjacent to the cavity 408. In the example, the material layer 402 may be supported via a support structure 410 so that it is adjacent to a microphone sensor inside the cavity 408. As shown, an air layer 404 may be formed between the material layer 402 and the surface of the microphone or housing 406.

[0032] Material layer 402 and air layer 404 allow for reduction of wind noise sensed by MEMS microphone 400. For example, partially correlated pressure fluctuations on the material layer that may be caused by wind accumulate in air layer 404, resulting in a reduction in wind noise as sensed by the microphone sensor in cavity 408. That is, wind in contact with MEMS microphone 400 generates pressure fluctuations on material layer 402 that are only partially correlated (e.g., have different phases). These pressure fluctuations propagate and accumulate in air layer 404, effectively canceling each other out due to their different phases. On the other hand, sound wave wavelengths have longer wavelengths compared to the size of the air layer. Furthermore, sound wave wavelengths are correlated on the surface of material layer 402 and are therefore not attenuated by material layer 402 and air layer 404. Thus, air layer 404 acts as an accumulator of wind-induced pressure fluctuations, and because the pressure fluctuations are partially correlated, they cancel each other out in air layer 404, resulting in minimal impact on the audio signal.

[0033] Figure 5This is a graph 500 showing the attenuation of audio signal 502 and wind noise 504 according to a specific aspect of this disclosure. As shown, the combination of material layer 402 and air layer 404 reduces wind noise 504 in the frequency band of interest (e.g., by up to 30 dB), while having little effect on audio signal 502. Wind noise reduction can be further improved by using a multilayer system, and thus the signal-to-wind noise ratio can be reduced. For example, multiple material layers with acoustic resistivity can be formed, each material layer forming an air layer between each layer.

[0034] Figure 6 An exemplary MEMS microphone 600, implemented according to a specific aspect of this disclosure, is shown, comprising multiple material layers having acoustic resistivity. As shown, the MEMS microphone 600 includes material layers 602, 606, and 402, each having acoustic resistivity and forming an air gap. For example, an air layer 604 is formed between material layers 602 and 606, an air layer 608 is formed between material layers 606 and 402, and an air layer 404 is formed between material layer 402 and a housing 406.

[0035] Figure 7A and Figure 7B These are graphs 700 and 701 illustrating the improvement in signal-to-noise ratio (SNR) of a MEMS microphone implemented using multiple material layers, relative to a single-material-layer implementation, according to a specific aspect of this disclosure. Graph 700 includes curve 702, which shows the improvement in SNR of a MEMS microphone implemented with two material layers having an acoustic impedance of 700 Rayles compared to a single-material-layer implementation (e.g., as per [reference to...]). Figure 4 (As described). Graph 700 also includes graph 704, which shows the improved signal-to-wind noise ratio of a MEMS microphone implemented with three material layers with an acoustic impedance of 700 Rayles compared to a single material layer implementation.

[0036] Graph 701 includes curve 706, which shows the improved signal-to-wind noise ratio of a MEMS microphone implemented with two material layers having an acoustic impedance of 3300 Rayles compared to a single material layer implementation. Graph 701 also includes curve 708, which shows the improved signal-to-wind noise ratio of a MEMS microphone implemented with three material layers having an acoustic impedance of 3300 Rayles compared to a single material layer implementation.

[0037] As shown in graphs 700 and 701, an improvement of up to 5 dB can be achieved compared to a single material layer implementation. Furthermore, an improvement in the trade-wind noise ratio is achieved within a favorable audio frequency band (e.g., between approximately 800 Hz and 5 kHz).

[0038] Figure 8An exemplary MEMS microphone 800 with a material layer implemented using a membrane 804 having acoustic impedance is shown according to a specific aspect of this disclosure. As shown, the membrane 804 forms an air layer 802 between the membrane 804 and the housing 406. The membrane 804 may be a waterproof and / or dustproof screen. Therefore, adding the membrane 804 improves the signal-to-noise ratio of the MEMS microphone 800 when manufacturing a dustproof and waterproof MEMS microphone 800. In a specific aspect, the membrane 804 may be used in addition to one or more material layers having acoustic resistivity, thereby providing further improvement in the signal-to-noise ratio of the MEMS microphone.

[0039] Figure 9 An exemplary MEMS microphone 900 having a membrane 804 and material layers 602, 606 according to a specific aspect of this disclosure is shown. Because the membrane 804 is implemented above the cavity 408, the MEMS microphone 900 can be waterproof and / or dustproof, while the implementation of material layers 602, 606 above the membrane 804 also provides an additional improvement in the signal-to-wind noise ratio of the MEMS microphone 900 compared to the MEMS microphone 800. Although in the exemplary MEMS microphone 900 the membrane 804 is implemented closer to the housing 406 than the material layers 602, 606, the membrane 804 and the material layers 602, 606 can be arranged adjacent to the housing 406 in any suitable order.

[0040] Because the total system impedance of the air layer (e.g., air layer 404) and the microphone is significantly higher than the impedance of the material layer (e.g., material layer 402), the technique described herein has almost no impact on the microphone's speech and audio pickup, thus resulting in a significant increase in the signal-to-noise ratio sensed by the microphone. In other words, the level of audio signal attenuation depends on the ratio of the impedance of material layer 402 to the total system impedance. With a high-impedance microphone, the total system impedance is much higher than the impedance of material layer 402, making the attenuation of the audio signal by material layer 402 relatively insignificant (e.g., minimal). Furthermore, due to the high impedance of the microphone, the microphone has almost no effect on the pressure in the air layer or the physical behavior of the material layer or membrane described herein, thus allowing for a relatively small cavity for the microphone. Therefore, sensors or pressure transducers implemented inside the cavity can be implemented as high-impedance devices, thereby reducing audio signal attenuation when using a relatively small cavity.

[0041] The material layer described herein can be implemented using any material with acoustic resistivity, or implemented as a membrane with acoustic impedance. For example, the material layer can be a screen, fabric (e.g., cloth), metal mesh, a plate with microperforations, a plastic film, or any material layer that acts as acoustic impedance. In certain aspects, the material layer can be implemented as a metal foam if it provides a reasonable acoustic resistivity. Depending on the application, the material layer can have a variety of acoustic impedance values.

[0042] Figure 10 This is a flowchart illustrating an exemplary operation 1000 for sensing an audio signal according to a specific aspect of this disclosure. Operation 1000 can be controlled by a microphone (such as...) Figure 4 , Figure 6 , Figure 8 and Figure 10 The microphone mentioned above is used for execution.

[0043] Operation 1000 begins at frame 1002, where a microphone senses an audio signal through at least one microphone sensor (e.g., a high-impedance microphone sensor, such as a MEMS microphone sensor) supported by a support structure (e.g., housing 406), and receives the audio signal through a first material layer (e.g., material layer 402) disposed adjacent to the microphone sensor. In certain aspects, the first material layer may be a screen of acoustically resistive material. In some cases, the first material layer is a membrane (e.g., membrane 804). This membrane may be waterproof and / or dustproof.

[0044] In certain aspects, a first air layer (e.g., air layer 404) is formed between the first material layer and the support structure, the first air layer being adjacent to the support structure. In some cases, the support structure is a housing having a cavity (e.g., cavity 408) in which at least one microphone sensor is located, and the first material layer is adjacent to the opening of the cavity.

[0045] In a particular aspect, audio signals are received via a second material layer (e.g., material layer 606) positioned adjacent to the first material layer. A second air layer (e.g., air layer 608) may be formed between the first and second material layers. In a particular aspect, audio signals are received via a third material layer (e.g., material layer 602) positioned adjacent to the second material layer. A third air layer (e.g., air layer 604) may be formed between the second and third material layers. In some cases, each of the first, second, and third material layers may be a film or layer of acoustically resistive material. In a particular aspect, operation 1000 continues at block 1004, where the microphone generates an electrical signal based on the audio signal via a microphone sensor.

[0046] The prior description of this disclosure is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the examples and designs described herein, but is given the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for reducing wind noise, comprising: A support structure, the support structure including at least one microphone sensor; as well as A first material layer is configured to be adjacent to the support structure, wherein a first air layer is formed between the first material layer and the support structure, the first air layer is adjacent to the microphone sensor, and is arranged such that some of the relevant pressure fluctuations on the first material layer caused by wind are canceled in the air layer, thereby improving the signal-to-noise ratio. as well as A second material layer is configured to be adjacent to the first material layer, wherein a second air layer is formed between the first material layer and the second material layer, thereby further improving the trade-wind noise ratio.

2. The device of claim 1, wherein the support structure comprises a housing having a cavity, the at least one microphone sensor being located within the cavity, and wherein the first material layer is adjacent to an opening of the cavity.

3. The apparatus according to claim 1, wherein the first material layer comprises a screen of acoustic damping material.

4. The apparatus of claim 1, wherein the first material layer comprises a film.

5. The apparatus of claim 4, wherein the membrane is at least one of waterproof or dustproof.

6. The apparatus of claim 1 further comprises a third material layer disposed adjacent to the second material layer, wherein a third air layer is formed between the second material layer and the third material layer.

7. The apparatus of claim 6, wherein each of the first material layer, the second material layer and the third material layer comprises a film or layer of acoustic damping material.

8. The apparatus of claim 1, wherein the at least one microphone sensor comprises a high-impedance microphone sensor.

9. The apparatus of claim 8, wherein the high-impedance microphone sensor comprises a microelectromechanical system (MEMS) microphone sensor.

10. A method for sensing an audio signal, comprising: The audio signal is sensed by at least one microphone sensor supported by a support structure, and received by a first material layer positioned adjacent to the microphone sensor, wherein a first air layer is formed between the first material layer and the support structure, the first air layer being adjacent to the support structure and arranged such that some of the relevant pressure fluctuations on the first material layer caused by wind are canceled out in the air layer, thereby improving the signal-to-wind noise ratio; wherein the audio signal is also received by a second material layer positioned adjacent to the first material layer, wherein a second air layer is formed between the first material layer and the second material layer to further improve the signal-to-wind noise ratio; as well as The microphone sensor generates an electrical signal based on the audio signal.

11. The method of claim 10, wherein the support structure comprises a housing having a cavity, the at least one microphone sensor being located within the cavity, and wherein the first material layer is adjacent to an opening in the cavity.

12. The method of claim 10, wherein the first material layer comprises a screen of acoustically resistive material.

13. The method of claim 10, wherein the first material layer comprises a film.

14. The method of claim 13, wherein the membrane is at least one of waterproof or dustproof.

15. The method of claim 10, wherein the audio signal is received via a third material layer configured to be adjacent to the second material layer, wherein a third air layer is formed between the second material layer and the third material layer.

16. The method of claim 15, wherein each of the first material layer, the second material layer, and the third material layer comprises a film or layer of acoustic damping material.

17. The method of claim 10, wherein the at least one microphone sensor comprises a high-impedance microphone sensor.

18. The method of claim 17, wherein the high-impedance microphone sensor comprises a microelectromechanical system (MEMS) microphone sensor.

Images