WO2013108081A1

WO2013108081A1 - Wind noise attenuation in microphones by controlled leakage

Info

Publication number: WO2013108081A1
Application number: PCT/IB2012/050269
Authority: WO
Inventors: Martin Nystrom
Original assignee: Sony Ericsson Mobile Communications Ab
Priority date: 2012-01-19
Filing date: 2012-01-19
Publication date: 2013-07-25

Abstract

The invention is directed to systems, methods and computer program products associated with a microphone system with an adjustable leakage aperture. An exemplary system includes a housing that encloses one or more parts of the microphone system, and a leakage aperture with an adjustable width provided between the housing and the atmosphere. The width of the leakage aperture determines a cutoff frequency for a high pass filter associated with the microphone system. The width of the leakage aperture may be increased, thereby resulting in a higher cutoff frequency for the high pass filter. The width of the leakage aperture may be decreased, thereby resulting in a lower cutoff frequency for the high pass filter.

Description

WIND NOISE ATTENUATION IN MICROPHONES

BY CONTROLLED LEAKAGE

BACKGROUND

[0001] A cutoff frequency of a microphone determines the signal frequencies that pass through a filter associated with the microphone and the signal frequencies that are attenuated by the filter. A microphone with a high cutoff frequency is desired when the microphone is being operated in a noisy environment (e.g., when a microphone is being operated in an open environment where wind noise is present). A microphone with a low cutoff frequency is desired when the microphone is being operated in a quiet environment (e.g., when a microphone is being operated in a closed environment where minimal wind noise is present). Currently, a microphone's cutoff frequency cannot be altered. Therefore, when a microphone with a high cutoff frequency is used in a quiet environment or is used for an application that requires a larger bandwidth, the microphone cannot record a larger bandwidth of frequencies. Similarly, when a microphone with a low cutoff frequency is used in a noisy environment or is used for an application that requires a smaller bandwidth, the microphone records low frequency signals associated with wind noise or any other type of low frequency noise. Therefore, what is needed is a microphone with an adjustable cutoff frequency so that the cutoff frequency can be altered based on the environment in which the microphone is operating and/or based on an application for which the microphone is being used.

BRIEF SUMMARY

[0002] Embodiments of the invention are directed to systems, methods and computer program products associated with a microphone system with adjustable leakage. An exemplary system includes a housing that at least partially encloses a cavity and an electrode; a moveable membrane that is attached to the housing and receives sound waves, the membrane and the electrode forming a capacitor, the sound waves causing the movable membrane to move thereby resulting in a change in the capacitor's capacitance; and a leakage aperture with an adjustable width provided between the housing and the atmosphere, the width of the leakage aperture determining a cutoff frequency for a high pass filter associated with the microphone system, wherein the width of the leakage aperture can be increased, the increased width of the leakage aperture resulting in a higher cutoff frequency for the high pass filter, and wherein the width of the leakage aperture can be decreased, the decreased width of the leakage aperture resulting in a lower cutoff frequency for the high pass filter.

[0003] In some embodiments, the high pass filter is an acoustic high pass filter.

In some embodiments, the width of the leakage aperture can be adjusted between at least two different width values. In some embodiments, the width of the leakage aperture can be reduced to zero. In some embodiments, the leakage aperture is positioned near the membrane. In some embodiments, the leakage aperture permits ventilation between the atmosphere and the housing.

[0004] In some embodiments, the leakage aperture is defined by at least one plate. In some embodiments, the breadth of the at least one plate is greater than a thickness of the housing. In some embodiments, the at least one plate is manufactured using at least one of electroactive polymeric material, electrostrictive material, or piezoelectric material.

[0005] In some embodiments, the system enables a user of the system to select at least one mode of operation, each mode of operation being associated with a different numerical value for the width of the leakage aperture. In some embodiments, a processor associated with the system automatically initiates adjustment of the width of the leakage aperture in response to at least one predetermined event.

[0006] In some embodiments, the system further comprises at least one noise- measuring sensor to measure noise associated with sound waves received at the membrane, wherein the at least one noise-measuring sensor is implemented at least in one of hardware or software.

[0007] In some embodiments, the system further comprises a processor configured to: determine a function that is at least one of currently being executed on the system or to be executed on the system within a predetermined period in the future, and at least one of: in response to determining the function is a voice call, cause the width of the leakage aperture to be decreased, or in response to determining the function is an audio or video recording, cause the width of the leakage aperture to be decreased.

[0008] In some embodiments, the system further comprises a processor configured to: determine a function that is at least one of currently being executed on the system or to be executed on the system within a predetermined period in the future; select, for the function, at least one of passing a larger frequency bandwidth of sound waves through the high pass filter or reducing a noise level associated with the sound waves; or at least one of: in response to selecting passing a larger frequency bandwidth of sound waves through the high pass filter, cause the width of the leakage aperture to be decreased, and in response to selecting passing a larger frequency bandwidth of sound waves through the high pass filter, cause the width of the leakage aperture to be increased.

[0009] In some embodiments, the system further comprises a processor configured to: determine a noise level associated with the sound waves received at the membrane, compare the noise level with a predetermined threshold, and at least one of: in response to determining the noise level is greater than the predetermined threshold, cause the width of the leakage aperture to be increased, or in response to determining the noise level is smaller than the predetermined threshold, cause the width of the leakage aperture to be decreased.

[0010] In some embodiments, the system further comprises a processor configured to: determine a current mode of operation of the system, the current mode of operation being associated with a cutoff frequency, determine a noise level associated with the sound waves received at the membrane, compare the noise level with a predetermined threshold, and at least one of: in response to determining both the noise level is greater than the predetermined threshold and the current mode of operation is associated with a lower cutoff frequency, cause the width of the leakage aperture to be increased, or in response to determining both the noise level is smaller than the predetermined threshold and the current mode of operation is associated with a higher cutoff frequency, cause the width of the leakage aperture to be decreased.

[0011] In some embodiments an exemplary method comprises providing a microphone system comprising: a housing that at least partially encloses a cavity and an electrode; a moveable membrane that is attached to the housing and receives sound waves, the membrane and the electrode forming a capacitor, the sound waves causing the movable membrane to move thereby resulting in a change in the capacitor's capacitance; and a leakage aperture with an adjustable width provided between the housing and the atmosphere, the width of the leakage aperture determining a cutoff frequency for a high pass filter associated with the microphone system; determining, by the microphone system, whether to adjust the width of the leakage aperture based at least partially on an application that is at least one of currently being executed on the microphone system or to be executed on the microphone system within a predetermined period in the future; and in response to determining the width of the leakage aperture is to be adjusted, initiate adjustment of the width of the leakage aperture. In some embodiments, the determining step further comprises determining, by the microphone system, whether to adjust the width of the leakage aperture based at least partially on a noise level associated with sound waves received at the membrane.

[0012] In some embodiments an exemplary computer program product comprises a non-transitory computer readable medium comprising code configured to: determine whether to adjust an adjustable width of a leakage aperture associated with a microphone system based at least partially on a noise level associated with sound waves received at a membrane associated with the microphone system; and in response to determining the width of the leakage aperture is to be adjusted, initiate adjustment of the width of the leakage aperture, wherein the microphone system comprises: a housing that at least partially encloses a cavity and an electrode; a moveable membrane that is attached to the housing and receives sound waves, the membrane and the electrode forming a capacitor, the sound waves causing the movable membrane to move thereby resulting in a change in the capacitor's capacitance; and the leakage aperture with the adjustable width provided between the housing and the atmosphere, the width of the leakage aperture determining a cutoff frequency for a high pass filter associated with the microphone system.

[0013] In some embodiments, the code configured to determine is further configured to determine whether to adjust the width of the leakage aperture based at least partially on an application that is at least one of currently being executed on the microphone system or to be executed on the microphone system within a predetermined period in the future. As used herein, an application (e.g., voice calling, audio or video recording, etc.) may also be referred to as a function.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Having thus described embodiments of the invention in general terms, reference will now be made to the accompanying drawings, where: Figure 1 is an exemplary microphone system with adjustable leakage, in accordance with embodiments of the present invention;

Figure 2 is exemplary microphone system with adjustable leakage, in accordance with embodiments of the present invention;

Figure 3 is exemplary microphone system with adjustable leakage, where the adjustable leakage aperture width is increased, in accordance with embodiments of the present invention;

Figure 4 is a frequency response chart associated with the exemplary microphone system presented in Figure 3, in accordance with embodiments of the present invention;

Figure 5 is exemplary microphone system with adjustable leakage, where the adjustable leakage aperture is decreased, in accordance with embodiments of the present invention;

Figure 6 is a frequency response chart associated with the exemplary microphone system presented in Figure 5, in accordance with embodiments of the present invention; and

Figure 7 is an exemplary process flow associated with a microphone system with adjustable leakage, in accordance with embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0015] Embodiments of the present invention now may be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure may satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0016] Embodiments of the invention are directed to systems, methods and computer program products for providing a microphone system with adjustable leakage, where the adjustable leakage permits the microphone system to adapt to various environmental conditions and/or various types of applications that are executed using the microphone system. An exemplary system includes a housing that encloses one or more parts of the microphone system, and a leakage aperture with an adjustable width provided between the microphone housing and the atmosphere. The width of the leakage aperture determines a cutoff frequency for a high pass filter associated with the microphone system. The width of the leakage aperture may be increased in a noisy environment or when an application requires a smaller frequency bandwidth, resulting in a higher cutoff frequency for the high pass filter. The width of the leakage aperture may be decreased in a quiet environment or when an application requires a larger frequency bandwidth, resulting in a lower cutoff frequency for the high pass filter. In some embodiments, the leakage aperture may be closed fully (e.g., width of zero).

[0017] Microphones are used for receiving audio input into a system, e.g., a computing system or a non-computing system. Sometimes, the audio may be a user's voice (e.g., when a user is participating in a voice call via the system). Other times, the audio may be environmental audio associated with an audio recording or a video recording. As used herein, a microphone may also be referred to as a microphone system. A microphone system may be any computing or non-computing system that comprises a microphone. Examples of microphone systems include, but are not limited to, stand-alone microphones, mobile computing devices (e.g., mobile phones), image- capturing devices (e.g., cameras), gaming devices, laptop computers, portable media players, tablet computers, e-readers, scanners, other portable or non-portable computing or non-computing devices, as well as, in some embodiments, one or more components thereof and/or one or more peripheral devices associated therewith.

[0018] Sometimes, the microphone is built into a system described herein. This built-in microphone may capture audio that is broadcast within a predetermined distance from the system. Other times, a wired microphone is plugged into an appropriate microphone jack associated with the system. At such times, a user of the microphone may have to bring the microphone close to the source of the audio (e.g., the user's lips) in order to input the audio (e.g., the user's voice) into the system via the microphone. Still other times, a wireless microphone may be carried by an audio source, and any audio signals received by the wireless microphone are wirelessly transmitted (e.g., via one or more short-range mechanisms such as near- field communication (NFC) or long- range wireless mechanisms (e.g., radio frequency (RF) communication) to a receiver associated with a computing or non-computing system described herein.

[0019] Omni-directional microphones are normally pressure sensors for an audio frequency range. A microphone as described herein comprises a membrane that encloses a closed cavity. In some embodiments, the microphone fully encloses the closed cavity, while in other embodiments, the microphone partially encloses the closed cavity. In some embodiments (e.g., Figure 1), the closed cavity includes a hollow or partially hollow back chamber. In some embodiments, pressure changes (due to sound waves) between the back chamber and the free air result in the membrane moving and taking a new position. Embodiments of the invention provide systems, methods, and computer program products to measure this movement and/or adjust this movement either automatically or manually.

[0020] Referring now to Figure 1, Figure 1 presents a microphone system 100.

In some embodiments, the microphone system may be a condenser microphone system. In other embodiments, the microphone system may be some other type of microphone system. The microphone system 100 is housed in a single microphone housing 105. In some embodiments, the microphone housing 105 at least partially surrounds a membrane 110, an electrode 130, and a back chamber 120. For example as shown in Figure 1, the microphone housing 105 at least partially encloses the membrane 110, the electrode 130, and the back chamber 120 on at least three sides or surfaces. The microphone housing 105 does not cover the membrane 110 to allow the membrane to receive sound waves. In some embodiments, the microphone system may be shaped as a cylinder (e.g., tubular) or as a cone. Therefore, while the microphone housing 105 defines at least two sides or surfaces of the microphone system (e.g., the longitudinal sides or surfaces of a cylindrical-shaped or conical-shaped microphone system), the membrane 110 defines at least one side or surface of the microphone system (e.g., the head of a cylindrical-shaped or conical-shaped microphone system). In other embodiments, the microphone housing 105 may define more or less than two sides or surfaces of the microphone system, and the membrane 110 may define more or less than one side or surface of the microphone system. In some embodiments, one or more electrical connections may pass through the microphone housing 105. As used herein, a side of the microphone housing may also be referred to as a surface of the microphone housing.

[0021] When sound pressure changes between the back chamber 120 and the free air (i.e., the atmosphere) cause the membrane 110 to move and take a new position, the distance between the membrane 110 and the electrode 130 changes (e.g., increases or decreases) resulting in a change of capacitance between the membrane 110 and the electrode 130. This change of capacitance may be read out or interpreted as an electrical signal. Therefore, the membrane 110 and the electrode 130 act as opposite plates of a capacitor. The membrane 110 may be a movable front plate, while the electrode 130 may be a back plate that is fixed in position. In some embodiments, the electrode 130 may be a movable plate as well.

[0022] In embodiments where the microphone system is a condenser microphone system, the microphone system may either be externally polarized or permanently polarized. An externally polarized microphone system may use an external power source to provide the polarizing voltage needed for the microphone capacitive circuit. A permanently polarized microphone system may have the polarizing voltage applied during the manufacture of the microphone system, and this polarizing voltage is retained by the microphone system during its lifetime.

[0023] In order to counter low frequency pressure changes such as weather changes or altitude changes that may affect the output of the microphone system, embodiments of the invention provide a leakage aperture 140 between the back chamber 120 and the atmosphere or the outside environment. This leakage aperture 140 may be a ventilation aperture in the microphone housing 105. Since wind noise is turbulent by nature, the leakage aperture 140 is placed near the membrane 110 of the microphone system. In the embodiment presented in Figure 1, the leakage aperture 140 is placed on the left side or surface of the housing 105. However, in other embodiments, the leakage aperture 140 may be placed on other sides or surfaces of the housing 105. For instance, the leakage aperture 140 may be placed on the right side or surface of the housing 105 or on the bottom side or surface of the housing 105. In some embodiments, the leakage aperture 140 is placed on either the left side or surface, or the right side or surface, of the housing 105 and as close as possible to the membrane 110. In some embodiments, more than one leakage aperture 140 may be provided. Each of the provided leakage apertures may be provided on the same side or surface of the housing 105, or on different sides or surfaces of the housing 105. Some of the leakage apertures may be adjustable and controllable as described herein, while other leakage apertures may be non-adjustable and/or non-controllable.

[0024] In some embodiments, the leakage aperture 140 may be substantially circular. This substantially circular leakage aperture 140 may be positioned on the surface of the microphone housing 105 and may be coupled with a substantially cylindrical tube located in the microphone housing 105 (e.g., the back chamber of the microphone housing 105). This substantially cylindrical leakage tube permits ventilation between the microphone housing 105 and the outside environment. Therefore, as used herein, the width of a leakage aperture 140 may refer to the diameter of a substantially circular leakage aperture 140 or the diameter of a substantially cylindrical leakage tube. As used herein, adjusting the width of the leakage aperture 140 may refer to adjusting the diameter of a substantially circular leakage aperture 140 or adjusting the diameter of a substantially cylindrical leakage tube. Although the leakage tube is located inside the microphone housing 105, in some embodiments, the leakage tube may slightly protrude outside the microphone housing through the substantially circular leakage aperture 140.

[0025] The leakage aperture 140 together with the back chamber 120 determines a cutoff frequency for an acoustic first order high pass filter associated with or defined by the microphone system. The acoustic first order high pass filter passes signals associated with frequencies higher than a cutoff frequency and attenuates (e.g., reduces the amplitude of) signals associated with frequencies lower than the cutoff frequency. Embodiments of the invention provide systems, methods, and computer program products to adjust the cutoff frequency. As used herein, a "cutoff frequency" is a cutoff frequency associated with an acoustic first order high pass filter.

[0026] Referring now to Figure 2, Figure 2 presents a microphone system 200, where the adjustable leakage aperture 140 is presented in greater detail. In some embodiments, the leakage aperture is defined by two opposing plates 142 and 144. The material that is used to manufacture each plate is described in further detail below. Each plate may either have the same thickness or different thickness. In some embodiments, as presented in Figure 2, the breadth B of each leakage aperture plate may extend beyond the thickness of the microphone housing 105. In other embodiments, the breadth B of each leakage aperture plate may not extend beyond the thickness of the microphone housing 105.

[0027] An acoustic filter described herein is superior to an electronic filter that filters audio frequencies in the electrical or electronic domain. As described previously, electronic signals are produced as a result of the change in capacitance of the capacitor defined by the membrane and the electrode in Figure 1 or Figure 2. An electronic filter filters these electronic signals. Therefore, in a microphone with an electronic filter, the input surface of the microphone receives a full bandwidth (e.g., 0 Hz to 20 kHz) of frequencies (e.g., audio or acoustic frequencies), and electronic signals corresponding to this full bandwidth of frequencies is input to the electronic filter. Since the full bandwidth of frequencies includes frequencies distorted by wind, the frequencies received by the electronic filter include audible artifacts that may not be able to be filtered by the electronic filter.

[0028] An acoustic filter as described herein filters, in the acoustic domain, frequencies received at the input surface (e.g., membrane) of the microphone. Therefore, the input acoustic signals received at the input surface of the microphone are filtered before the input signals are converted into electronic signals. Thus, in an embodiment with an acoustic filter, electronic signals produced by a change in capacitance of the capacitor correspond to a smaller bandwidth of audio or acoustic frequencies. In some embodiments, an electronic filter may be used in addition to an acoustic filter. In some embodiments, an acoustic high pass filter described herein may be replaced with an electronic high pass filter.

[0029] In some embodiments, for a microphone system that does not attenuate low frequencies, the cutoff frequency may be set to 1 - 5 Hz. However, the cutoff frequency may be set higher or lower than the range described herein. In some embodiment, the cutoff frequency may be set to 0 Hz. A microphone system that does not attenuate low frequencies has a flat frequency response at low frequencies. A microphone system that has a flat frequency response at low frequencies may not attenuate wind noise and may allow a larger bandwidth of audio frequencies (sometimes referred to as a full audio bandwidth) to be input into the microphone system. In some embodiments, for a microphone system that attenuates low frequencies, the cutoff frequency may be set to 100 - 200 Hz. However, the cutoff frequency may be set higher or lower than the range described herein. A microphone system that attenuates low frequencies may be used to attenuate wind noise.

[0030] Embodiments of the invention are directed to producing systems, methods, and computer program products that are designed to attenuate wind noise in situations where wind noise is present (e.g., when a magnitude of wind noise is greater than a predetermined noise threshold) when a microphone system is in operation, and that are designed to provide a larger or full bandwidth of frequencies when wind noise is minimal (e.g., when a magnitude of wind noise is smaller than a predetermined noise threshold) when the microphone system is in operation. As used herein, a full bandwidth may refer to embodiments of a microphone system where there is no cutoff frequency (e.g., cutoff frequency set to 0 Hz) or a microphone system where the cutoff frequency is low (e.g., cutoff frequency set to 1-5 Hz). Therefore, embodiments of the invention are directed to systems, method, and computer program products that are designed to adjust a cutoff frequency of a microphone system.

[0031] A microphone system as described herein may determine the environment in which a microphone system is to be operated in or is operating in. Therefore, the determining step may be executed either prior to beginning operation of the microphone system (i.e., receiving audio input) or after beginning operation of the microphone system. In some embodiments, the determining step may comprise determining noise levels associated with at least one of the environment in which the microphone system is located, or associated with audio input received at the microphone system. In some embodiments, one or more noise-measuring sensors (implemented at least in one of hardware or software) that are comprised in the microphone housing may be used to determine noise levels associated with audio frequencies that are received at the membrane associated with the microphone system or associated with the environment in which the microphone system is being operated. A hardware-implemented sensor may directly measure at least one of the noise level associated with sound waves received at the membrane or the general noise level (e.g., wind noise level) associated with the environment in which the microphone system is being operated. A software

implemented sensor may analyze the sound waves received at the microphone system (e.g., a membrane), and using one or more algorithms, determine the noise level associated with the sound waves received at the microphone system.

[0032] Therefore, embodiments of the invention may initially determine and distinguish useful audio signals from noisy audio signals. After determining and distinguishing useful audio signals from noisy audio signals (e.g., wind noise), a system as described herein may measure the magnitude of the noisy audio signals. As used herein, useful audio signals include audio signals that are desired to be input via a microphone system (e.g., a user's voice, desirable audio associated with subjects in the environment, etc.). In some embodiments, a system as described herein may periodically execute the determining step described previously. As described anywhere in this specification, any operation that is performed by the microphone system may

additionally or alternatively be performed by a computing system that is in wired or wireless communication with the microphone system.

[0033] The microphone system may subsequently compare the magnitude (e.g., amplitude) of the noisy audio signals with one or more predetermined magnitude values. Additionally, the microphone system may determine the current mode of operation of the microphone system. In some embodiments, the microphone system may have two modes of operation: one for wind noise attenuation (higher cutoff frequency, smaller bandwidth) and one for higher or full audio bandwidth (lower cutoff frequency, higher bandwidth). In response to determining that the microphone system is currently in a full audio bandwidth mode and in response to determining the magnitude of the noise signals are greater than one or more predetermined magnitude values, the microphone system may switch to a wind noise attenuation mode. In response to determining that the microphone system is currently in in a wind noise attenuation mode and in response to determining the magnitude of the noise signals are greater than one or more

predetermined magnitude values, the microphone system may continue to remain in or operate in a wind noise attenuation mode. In response to determining that the

microphone system is currently in a wind noise attenuation mode and in response to determining the magnitude of the noise signals is less than one or more predetermined magnitude values, the microphone system may switch to a full audio bandwidth mode. In response to determining that the microphone system is currently in in a wind noise attenuation mode and in response to determining the magnitude of the noise signals are greater than one or more predetermined magnitude values, the microphone system may continue to remain in or operate in a wind noise attenuation mode. As used herein, the full audio bandwidth mode may also be referred to a high audio bandwidth mode, and the wind noise attenuation mode may also be referred to as a low audio bandwidth mode.

[0034] In some embodiments, the full audio bandwidth mode may be a mode of operation that is automatically selected by a system described herein when the system determines that the user is currently recording audio or video using the system, or when the system is about to record audio or video using the system. In some embodiments, the wind noise attenuation mode may be a mode of operation that is automatically selected by a system described herein when the system determines that the user is currently engaging in a voice call, or when the system is about to engage in a voice call (e.g., when the system receives a telephone call).

[0035] A system as described herein permits shifting of a cutoff frequency between two values: one for wind noise attenuation and one for full audio bandwidth. In some embodiments, the system may permit shifting of a cutoff frequency between more than two values (or between a continuous range of values), where each value on the continuous range is associated with a particular measured value of wind noise. A higher cutoff frequency may be associated with a higher measured value of wind noise and a lower cutoff frequency may be associated with a lower measured value of wind noise.

[0036] Referring now to Figures 3 and 4, Figure 3 presents a microphone 300 with a large leakage aperture 140 and Figure 4 presents a frequency response 400 associated with the microphone presented in Figure 3. The large leakage aperture presented in Figure 3 results in a higher cutoff frequency for the high pass filter described herein. This higher cutoff frequency is visible in Figure 4. While signal frequencies greater than the cutoff frequency are not attenuated, signal frequencies smaller than the cutoff frequency are attenuated.

[0037] Referring now to Figures 5 and 6, Figure 5 presents a microphone 500 with a small leakage aperture 140 and Figure 6 presents a frequency response 600 associated with the microphone presented in Figure 5. The small leakage aperture presented in Figure 5 results in a lower cutoff frequency for the high pass filter described herein. This lower cutoff frequency is visible in Figure 6. Therefore, this lower cutoff frequency enables a larger bandwidth of audio frequencies to pass through the high pass filter. Furthermore, the attenuation of the low signal frequencies for the microphone in Figure 5 is smaller than the attenuation of the low signal frequencies for the microphone in Figure 3.

[0038] A tradeoff exists between the amount of filtering associated with a high pass filter and the bandwidth of audio frequencies that pass through the high pass filter without attenuation. A higher cutoff frequency results in greater amount of filtering of wind noise, but a smaller bandwidth of audio frequencies that pass through the high pass filter. A lower cutoff frequency results in a larger bandwidth of audio frequencies that pass through the high pass filter. The present invention is directed to automatically selecting or tuning a cutoff frequency to optimize the tradeoff between wind noise suppression and the bandwidth of audio frequencies that pass through the high pass filter. The cutoff frequency may be tuned or selected using one or more executable software algorithms that are stored in the system. In some embodiments, a software algorithm as described herein may be configured to select a cutoff frequency based on a type of function currently in operation (e.g., voice call, audio or video recording etc.) on the microphone system. This software algorithm may be executed by a computing processor associated with the microphone system.

[0039] In some embodiments, when the software algorithm determines that passing a larger bandwidth of audio frequencies is more important (e.g., for voice calls) than attenuating the low frequency signals (e.g., noisy signals) for better or optimal performance of a function that is at least one of currently being executed on the microphone system or to be executed on the microphone system within a predetermined period in the future, the algorithm may choose a lower cutoff frequency even if the magnitude of the low frequency signals is greater than a first predetermined threshold. However, in some embodiments, the algorithm may choose a slightly higher cutoff frequency (compared to the lower cutoff frequency) if the magnitude of the low frequency signals is greater than a second predetermined threshold, which is higher than the first predetermined threshold. The microphone system described herein selects the cutoff frequency by adjusting the width of the leakage aperture. Each width value associated with the leakage aperture corresponds to a different cutoff frequency associated with the high pass filter.

[0040] As a further example, in some embodiments, when the software algorithm determines the attenuation of low frequency signals (e.g., noisy signals) is more important (e.g., for audio or video recording) than the passage of a larger bandwidth of audio frequencies for better or optimal performance of a function that is at least one of currently being executed on the microphone system or to be executed on the microphone system within a predetermined period in the future, the algorithm may choose a higher cutoff frequency even if the magnitude of the low frequency signals is smaller than a third predetermined threshold. However, in some embodiments, the algorithm may choose a slightly lower cutoff frequency (compared to the higher cutoff frequency) if the magnitude of the low frequency signals is smaller than a fourth predetermined threshold, which is lower than the third predetermined threshold.

[0041] In some embodiments, the plates of the leakage aperture are manufactured using at least one of electrostrictive material, electroactive polymeric material, or piezoelectric material, or using a combination of any of these materials. For instance, in some embodiments, one plate that defines the leakage aperture may be manufactured with one type of material, and another plate (e.g., the opposing plate) that defines the leakage aperture may be manufactured with a different type of material. In some embodiments, one plate may be maintained in a constant position, while the other plate may change its size, shape, or position under the application of an electric field. The invention is not limited to any particular material that is used to manufacture the plates that define the leakage aperture. In some embodiments, application of an electric field may also move the position of the leakage aperture along the side or surface of the microphone housing. Thus, the leakage aperture may be moved closer to or further away from the membrane associated with the microphone system.

[0042] An electrostrictive material is a dielectric material that changes its size, shape, or position under the application of an electric field. Therefore, when an electrostrictive material is used to manufacture the plates of the leakage aperture, the width between the plates, or the diameter of the leakage aperture, may be altered by applying an electric field to only one of the plates or to each of the plates that define the leakage aperture. An electroactive polymeric material is a polymeric material that changes its size, shape, or position under the application of an electric field. Therefore, when an electroactive polymeric material is used to manufacture the plates of the leakage aperture, the width between the plates, or the diameter of the leakage aperture, may be altered by applying an electric field to only one of the plates or to each of the plates that define the leakage aperture.

[0043] A piezeoelectric material is a material that exhibits a piezoelectric effect.

A piezoelectric material may either be natural or man-made. The piezoelectric effect is a linear electromechanical interaction between an electrical state and a mechanical state in a piezoelectric material. A piezoelectric material accumulates electrical charge in response to a mechanical stress that is applied to the material. A piezoelectric material may also exhibit a reverse piezoelectric effect. Therefore, a mechanical stress or strain may be produced in the piezoelectric material in response to an electric field that is applied to the piezoelectric material. Thus, when a piezoelectric material is used to manufacture the plates of the leakage aperture, a mechanical strain or stress may be produced in the plates when an electric field is applied to the plates. The mechanical stress may result in a change in size, shape, or position of the piezoelectric plate.

Therefore, when a piezoelectric material is used to manufacture the plates of the leakage aperture, the width between the plates, or the diameter of the leakage aperture, may be altered by applying an electric field to only one of the plates or to each of the plates that define the leakage aperture.

[0044] The adjusting process described herein may not only permit adjustment of the width of the leakage aperture, but may also permit movement of the leakage aperture along the sides of the microphone housing. For example, for the leakage aperture presented in Figure 1, adjusting the leakage aperture may cause the leakage aperture to move closer to or further away from the membrane. In some embodiments, where the low frequency signals (e.g., noise signals) are determined to be greater than a

predetermined threshold level, the system may automatically move the leakage aperture, which is located along a side or surface of the microphone housing as in Figure 1 , closer to the membrane. In some embodiments, where the low frequency audio signals are determined to be greater than a predetermined threshold level, the system may automatically move the leakage aperture, which is located along a side or surface of the microphone housing as in Figure 1, further away from the membrane.

[0045] The leakage aperture described herein may permit ventilation, i.e., the movement of air through the leakage aperture so that the pressure inside the microphone is substantially similar to the pressure outside the microphone.

[0046] In some embodiments, a microphone system as described herein may permit a user to manually select one or more modes (e.g., a wind noise suppression mode, a full audio bandwidth mode, etc.). In other embodiments, a microphone system as described herein may permit a user to manually select a cutoff frequency associated with a filter. In some embodiments, a user may enter a cutoff frequency value using one or more input mechanisms described herein (e.g., keypad input, touchscreen input, voice input, etc.). Therefore, in such manual embodiments, a user may set the cutoff frequency value or choose an appropriate mode based on a perceived amount of wind noise as sensed by the user of the system. Based on the user input, the microphone system may initiate adjustment of the width of the leakage aperture so that the adjusted width corresponds with the selected cutoff frequency value or the selected mode. In some embodiments, a user may directly input into the microphone system a value for the width of the leakage aperture. Based on the user input, the microphone system initiates adjustment of the width of the leakage aperture.

[0047] Referring now to Figure 7, Figure 7 presents a process flow 700 for an exemplary microphone system with adjustable leakage. At block 710, a processor associated with the microphone system may determine a current mode of operation of the microphone system. Exemplary modes may include a wind noise attenuation mode, a full audio bandwidth mode, etc. As described previously, in some embodiments, there may be more than two modes of operation for the microphone system. Each mode of operation is associated with a separate cutoff frequency for a high pass filter associated with the microphone system.

[0048] At block 720, a processor associated with the microphone system may determine a function being executed or a function to be executed on the microphone system. Exemplary functions include using the microphone system to engage in a voice call, record audio or video, etc. Exemplary functions are not limited to those described herein. As used herein, a function may also be referred to as an application.

[0049] At block 730, a processor associated with the microphone system may determine low frequency signal levels (e.g., noise levels) associated with at least one of the current environment in which the microphone system is being operated or associated with signals received as input to the microphone system (e.g., sound waves or signals received at the membrane of the microphone system). In some embodiments, a processor described herein may determine that any frequencies lower than a

predetermined frequency constitute noise. In some embodiments, the microphone system may determine the magnitude or levels associated with the low frequency noise signals using one or more hardware sensors. Additionally or alternatively, in other embodiments, the microphone system may determine the levels associated with the low frequency noise signals using one or more software algorithms that analyze the frequencies that are input into the microphone system and determines the level(s) associated with the low frequency noise signals. [0050] At block 740, a processor associated with the microphone system may determine the frequency bandwidth required for a function that is at least one of currently being executed on the microphone system or a function to be executed on the

microphone system within a predetermined period of time in the future. For example, the microphone system may determine a frequency bandwidth required for conducting a voice call, recording audio or video, etc. In some embodiments, the microphone system may prompt a user (via a user interface associated with the microphone system) requesting the user whether the user wants to increase or decrease the frequency bandwidth for a function that is at least one of currently being executed on the microphone system or a function to be executed on the microphone system within a predetermined period of time in the future. The microphone system may prompt the user to increase the frequency bandwidth when the microphone system determines that a low frequency signal level (e.g., noise level) associated with the environment in which the microphone system is being operated is below a predetermined threshold level. The microphone system may prompt the user to decrease the frequency bandwidth when the microphone system determines that a low frequency signal level (e.g., noise level) associated with the environment in which the microphone system is being operated is above a predetermined threshold level. Subsequently, the microphone system receives the user input via the user interface. If the user chooses to decrease the frequency bandwidth, the microphone system initiates an increase in the width of the leakage aperture. If the user chooses to increase the frequency bandwidth, the microphone system initiates a decrease in the width of the leakage aperture. An exemplary user interface may be a display associated with the microphone system. The display may be a display included with the microphone system or located remotely from the microphone system.

[0051] At block 750, the microphone system may access or determine one or more pre-stored user preference. For example, a user may store, in the microphone system, the user's preferred frequency bandwidth for voice calls, audio or video recording, etc. Additionally, the user may store, in the microphone system, the user's preferred mode of operation for various environments, where each environment may be associated with a particular low frequency signal or noise level. [0052] At block 760, the microphone system may determine whether to adjust the width of the leakage aperture associated with the microphone system. Adjusting the width of the leakage aperture changes the cutoff frequency associated with a high pass filter described herein. The determining step at block 760 is based at least partially on at least one of the process blocks 710, 720, 730, 740, and 750. Additionally or

alternatively, as explained previously, the microphone system may select a width for the leakage aperture in order to optimize the tradeoff between the amount of filtering associated with an acoustic high pass filter and the bandwidth of audio frequencies that pass through the acoustic filter without attenuation. Therefore, the width of the leakage aperture (and consequently the cutoff frequency) may be automatically controlled by the microphone system. Alternatively, as explained previously, a user of the microphone system may manually control the width of the leakage aperture by selecting one or more modes of operation, each mode of operation being associated with a different width for the leakage aperture.

[0053] In some embodiments, the process flow may be performed in the order shown in Figure 7, while in other embodiments, the process flow may be performed in a different order from that presented in Figure 7.

[0054] As used herein, the term "automatic" refers to a function, a process, a method, or any part thereof, which is executed by computer software upon occurrence of an event or a condition without intervention by a user.

[0055] As used herein, the terms "smaller" and "lower" are equivalent and may be used interchangeably. Additionally, as used herein, the terms " greater" and "higher" are equivalent and may be used interchangeably.

[0056] In accordance with embodiments of the invention, the term "module" with respect to a system (or a device) may refer to a hardware component of the system, a software component of the system, or a component of the system that includes both hardware and software. As used herein, a module may include one or more modules, where each module may reside in separate pieces of hardware or software.

[0057] Although many embodiments of the present invention have just been described above, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Also, it will be understood that, where possible, any of the advantages, features, functions, devices, and/or operational aspects of any of the embodiments of the present invention described and/or contemplated herein may be included in any of the other embodiments of the present invention described and/or contemplated herein, and/or vice versa. In addition, where possible, any terms expressed in the singular form herein are meant to also include the plural form and/or vice versa, unless explicitly stated otherwise. Accordingly, the terms "a" and/or "an" shall mean "one or more," even though the phrase "one or more" is also used herein. Like numbers refer to like elements throughout.

[0058] As will be appreciated by one of ordinary skill in the art in view of this disclosure, the present invention may include and/or be embodied as an apparatus (including, for example, a system, machine, device, computer program product, and/or the like), as a method (including, for example, a business method, computer- implemented process, and/or the like), or as any combination of the foregoing.

Accordingly, embodiments of the present invention may take the form of an entirely business method embodiment, an entirely software embodiment (including firmware, resident software, micro-code, stored procedures in a database, etc.), an entirely hardware embodiment, or an embodiment combining business method, software, and hardware aspects that may generally be referred to herein as a "system." Furthermore, embodiments of the present invention may take the form of a computer program product that includes a computer-readable storage medium having one or more computer- executable program code portions stored therein. As used herein, a processor, which may include one or more processors, may be "configured to" perform a certain function in a variety of ways, including, for example, by having one or more general-purpose circuits perform the function by executing one or more computer-executable program code portions embodied in a computer-readable medium, and/or by having one or more application-specific circuits perform the function.

[0059] It will be understood that any suitable computer-readable medium may be utilized. The computer-readable medium may include, but is not limited to, a non- transitory computer-readable medium, such as a tangible electronic, magnetic, optical, electromagnetic, infrared, and/or semiconductor system, device, and/or other apparatus. For example, in some embodiments, the non-transitory computer-readable medium includes a tangible medium such as a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable readonly memory (EPROM or Flash memory), a compact disc read-only memory (CD- ROM), and/or some other tangible optical and/or magnetic storage device. In other embodiments of the present invention, however, the computer-readable medium may be transitory, such as, for example, a propagation signal including computer-executable program code portions embodied therein.

[0060] One or more computer-executable program code portions for carrying out operations of the present invention may include object-oriented, scripted, and/or unscripted programming languages, such as, for example, Java, Perl, Smalltalk, C++, SAS, SQL, Python, Objective C, JavaScript, and/or the like. In some embodiments, the one or more computer-executable program code portions for carrying out operations of embodiments of the present invention are written in conventional procedural

programming languages, such as the "C" programming languages and/or similar programming languages. The computer program code may alternatively or additionally be written in one or more multi-paradigm programming languages, such as, for example, F#.

[0061] Some embodiments of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of apparatus and/or methods. It will be understood that each block included in the flowchart illustrations and/or block diagrams, and/or combinations of blocks included in the flowchart illustrations and/or block diagrams, may be implemented by one or more computer-executable program code portions. These one or more computer-executable program code portions may be provided to a processor of a general purpose computer, special purpose computer, and/or some other programmable data processing apparatus in order to produce a particular machine, such that the one or more computer-executable program code portions, which execute via the processor of the computer and/or other programmable data processing apparatus, create mechanisms for implementing the steps and/or functions represented by the flowchart(s) and/or block diagram block(s).

[0062] The one or more computer-executable program code portions may be stored in a transitory and/or non-transitory computer-readable medium (e.g., a memory, etc.) that can direct, instruct, and/or cause a computer and/or other programmable data processing apparatus to function in a particular manner, such that the computer- executable program code portions stored in the computer-readable medium produce an article of manufacture including instruction mechanisms which implement the steps and/or functions specified in the flowchart(s) and/or block diagram block(s).

[0063] The one or more computer-executable program code portions may also be loaded onto a computer and/or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer and/or other programmable apparatus. In some embodiments, this produces a computer-implemented process such that the one or more computer-executable program code portions which execute on the computer and/or other programmable apparatus provide operational steps to implement the steps specified in the flowchart(s) and/or the functions specified in the block diagram block(s). Alternatively, computer-implemented steps may be combined with, and/or replaced with, operator- and/or human-implemented steps in order to carry out an embodiment of the present invention.

[0064] While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other changes, combinations, omissions, modifications and substitutions, in addition to those set forth in the above paragraphs, are possible. Those skilled in the art will appreciate that various adaptations, modifications, and combinations of the just described embodiments can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.

Claims

WHAT IS CLAIMED IS:

1. A microphone system comprising:

a housing that at least partially encloses a cavity and an electrode;

a moveable membrane that is attached to the housing and is configured to receive sound waves, the membrane and the electrode forming a capacitor, the sound waves causing the movable membrane to move thereby resulting in a change in the capacitor's capacitance; and

a leakage aperture with an adjustable width provided between the housing and the atmosphere, the width of the leakage aperture determining a cutoff frequency for a high pass filter associated with the microphone system,

wherein the width of the leakage aperture can be increased, the increased width of the leakage aperture resulting in a higher cutoff frequency for the high pass filter, and wherein the width of the leakage aperture can be decreased, the decreased width of the leakage aperture resulting in a lower cutoff frequency for the high pass filter.

2. The system of claim 1, wherein the high pass filter is an acoustic high pass filter.

3. The system of claim 1, wherein the width of the leakage aperture can be adjusted between at least two different width values.

4. The system of claim 1, wherein the width of the leakage aperture can be reduced to zero.

5. The system of claim 1, wherein the leakage aperture is positioned near the membrane.

6. The system of claim 1, wherein the leakage aperture is defined by at least one plate.

7. The system of claim 6, wherein the breadth of the at least one plate is greater than a thickness of the housing.

8. The system of claim 6, wherein the at least one plate is manufactured using at least one of electroactive polymeric material, electrostrictive material, or piezoelectric material.

9. The system of claim 1, wherein the leakage aperture permits ventilation between the atmosphere and the housing.

10. The system of claim 1, wherein the system enables a user of the system to select at least one mode of operation, each mode of operation being associated with a different numerical value for the width of the leakage aperture.

11. The system of claim 1 , wherein a processor associated with the system automatically initiates adjustment of the width of the leakage aperture in response to at least one predetermined event.

12. The system of claim 1, further comprising:

at least one noise-measuring sensor to measure noise associated with sound waves received at the membrane, wherein the at least one noise-measuring sensor is implemented in at least one of hardware or software.

13. The system of claim 1, further comprising:

a processor configured to:

determine a function that is at least one of currently being executed on the system or to be executed on the system within a predetermined period in the future, and

at least one of:

in response to determining the function is a voice call, cause the width of the leakage aperture to be decreased, or

in response to determining the function is an audio or video recording, cause the width of the leakage aperture to be decreased.

14. The system of claim 1, further comprising:

a processor configured to:

determine a function that is at least one of currently being executed on the system or to be executed on the system within a predetermined period in the future,

select, for the function, at least one of passing a larger frequency bandwidth of sound waves through the high pass filter or reducing a noise level associated with the sound waves, and

at least one of:

in response to selecting passing a larger frequency bandwidth of sound waves through the high pass, cause the width of the leakage aperture to be decreased, or

in response to selecting reducing a noise level associated with the sound waves, cause the width of the leakage aperture to be increased.

15. The system of claim 1, further comprising:

a processor configured to:

determine a noise level associated with the sound waves received at the membrane,

compare the noise level with a predetermined threshold, and

at least one of:

in response to determining the noise level is greater than the predetermined threshold, cause the width of the leakage aperture to be increased, or

in response to determining the noise level is smaller than the predetermined threshold, cause the width of the leakage aperture to be decreased.

16. The system of claim 1, further comprising:

a processor configured to:

determine a current mode of operation of the system, the current mode of operation being associated with a cutoff frequency,

compare the noise level with a predetermined threshold, and

at least one of:

in response to determining both the noise level is greater than the predetermined threshold and the current mode of operation is associated with a lower cutoff frequency, cause the width of the leakage aperture to be increased, or

in response to determining both the noise level is smaller than the predetermined threshold and the current mode of operation is associated with a higher cutoff frequency, cause the width of the leakage aperture to be decreased.

17. A method to adjust a leakage aperture associated with a microphone system, the method comprising:

providing a microphone system comprising:

a housing that at least partially encloses a cavity and an electrode;

a moveable membrane that is attached to the housing and that is configured to receive sound waves, the membrane and the electrode forming a capacitor, the sound waves causing the movable membrane to move thereby resulting in a change in the capacitor's capacitance; and

a leakage aperture with an adjustable width provided between the housing and the atmosphere, the width of the leakage aperture determining a cutoff frequency for a high pass filter associated with the microphone system;

determining, by the microphone system, whether to adjust the width of the leakage aperture based at least partially on an application that is at least one of currently being executed on the microphone system or to be executed on the microphone system within a predetermined period in the future; and

in response to determining the width of the leakage aperture is to be adjusted, initiate adjustment of the width of the leakage aperture.

18. The method of claim 17, wherein the determining step further comprises determining, by the microphone system, whether to adjust the width of the leakage aperture based at least partially on a noise level associated with sound waves received at the membrane.

19. A computer program product to adjust a leakage aperture associated with a microphone system, the computer program product comprising:

a non-transitory computer readable medium comprising code configured to: determine whether to adjust an adjustable width of a leakage aperture associated with a microphone system based at least partially on a noise level associated with sound waves received at a membrane associated with the microphone system; and

in response to determining the width of the leakage aperture is to be adjusted, initiate adjustment of the width of the leakage aperture, wherein the microphone system comprises:

a housing that at least partially encloses a cavity and an electrode;

the leakage aperture with the adjustable width provided between the housing and the atmosphere, the width of the leakage aperture determining a cutoff frequency for a high pass filter associated with the microphone system.

20. The computer program product of claim 19, wherein the code is configured to determine whether to adjust the width of the leakage aperture based at least partially on an application that is at least one of currently being executed on the microphone system or to be executed on the microphone system within a predetermined period in the future.