Hearing aids that provide protection against sudden loud noises

Abstract

The hearing aid includes a microphone and a processing unit. The microphone is configured to receive a sound incident on the hearing aid and send a corresponding microphone output to the processing unit. The processing unit is configured to process the microphone output to determine whether the incident sound includes a potentially harmful sound and generate a processor output including a processed version of the microphone output. A method of protecting a hearing aid wearer from sudden loud sounds includes receiving an incident sound using a microphone in the hearing aid and sending a corresponding microphone output to a processing unit in the hearing aid. The processing unit processes the microphone output to generate a first processor output determined by whether the incident sound includes a potentially harmful impulse sound and a second processor output including a processed version of the microphone output.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. patent application Ser. No. 17 / 693,152, filed Mar. 11, 2022, entitled "HEARING AIDS PROVIDING PROTECTION AGAINST SUDDEN LOUD SOUNDS," which is hereby incorporated by reference for all purposes as if fully set forth herein. [Background technology]

[0002] Loud sounds can have a very detrimental effect on hearing. People who are occasionally or regularly exposed to such sounds, for example in their occupation, can protect themselves by wearing earplugs or headphones that reduce or block the sound, but this protection generally also blocks other low-volume sounds that the wearer would ideally like to hear (such as normal conversations and telephone ringing). In some situations, the loss of these "safe" sounds is worth accepting in order to avoid the risk of serious, even irreversible, damage caused by loud sounds. However, in many situations, especially when loud sounds occur rarely, people often run the risk of damage by choosing to use protective devices not as a preventative measure, but only after the sound has reached an uncomfortably loud level. This is especially problematic when the loud sound is impulsive, that is, a sound that begins suddenly, rises rapidly, and in most cases decays rapidly, with a short duration, usually less than one second. Because such sounds rise suddenly, people exposed to them may not have time to take appropriate measures before they reach dangerously high values.

[0003] Throughout the remainder of this disclosure, the term "impulsive" is defined to mean a noise of less than 1 second duration that rises from a safe level to approaching (or exceeding) a potentially harmful level within 0.5 seconds. The terms "safe" and "harmful" should be understood to include combinations of volume and duration. For example, a noise of volume "A" dBA that lasts for "X" seconds is considered safe, but the same noise of volume "A" dBA that lasts for "3X" seconds is considered potentially harmful.

[0004] Now consider the specific circumstances that affect a hearing-impaired person wearing a hearing aid to amplify the sound waves received from an initial volume that is difficult for the person to hear to a level that the person can hear. An incident sound that is tolerably loud for a non-hearing person may therefore be audible "naturally," but may be problematic for a hearing-impaired person who hears an amplified version of that sound that is sent through the hearing aid to the ear canal. Fortunately, hearing aids have limitations on the volume of sounds that are amplified. However, the sound may enter the ear directly through certain open vents in the hearing aid earpiece, or it may be conducted through the body of the earpiece and enter the hearing canal.

[0005] Because the sound is environmental, there is no impact if the wearer turns off the hearing aid or removes the part of the hearing aid that transmits the sound (the speaker or audio guide tube) from the ear.

[0006] Currently available hearing aids have signal processing circuits that are typically designed to adapt to the wearer's audio profile and may in fact show large "dips" indicative of impairment in any audio frequency band. Age-related hearing impairment is usually related to the high frequencies that are related to speech recognition. At age 40, the average person experiences a 20 dB loss of hearing at frequencies above 3 kHz, and by age 70, a 50 dB loss. For this type of impairment, the hearing aid attempts to accommodate these high frequencies necessary to distinguish consonants in spoken language. The hearing aid selectively amplifies these frequencies, leaving other frequencies alone or attenuating them in relation to other frequencies that are usually associated with less significant ambient noise. As mentioned above, the processing can be tailored to the individual's hearing impairment profile and can also adapt to different ambient sound environments (e.g., crowded rooms, concert halls, busy streets during commutes, etc.). However, current approaches are inadequate to deal with situations where the environmental sound is very loud. Because the volume threshold is exceeded, the hearing aid does not amplify the sound, but the wearer may suffer further hearing impairment. It would be desirable to have a hearing aid that offered some protection from loud sounds, especially sudden, unexpected and harmful sounds.

[0007] Many hearing aids that seal the ear canal, for example in-the-ear or in-the-canal, perform a type of passive noise cancellation by blocking the direct path for sound to enter the ear canal. Some hearing aids have active vent technology that opens or closes a vent in the earpiece of the hearing aid depending on the hearing mode. For example, when the vent is open, low frequency sounds enter the ear canal directly, but when the vent is closed, low frequency sounds do not enter. When streaming music directly to the hearing aid, a closed vent is often preferred because the sound sounds more natural to the wearer because the low frequency sounds emitted by the hearing aid stay in the ear canal and are not mixed with low frequencies from outside. In some cases, this vent control is automatically activated, for example in response to detecting the type of sound environment in which the music is being played. However, to date, active vent technology has not been used or proposed to be used in combination with impulse noise detection.

[0008] The basic idea of ​​active noise cancellation - essentially adding an out-of-phase sound to the sound you want to cancel - dates back to at least the 1930s. Its application to headphones began in the 1950s, but development boomed in the late 1980s, and the technology is now widely used in many readily available consumer products.

[0009] Active noise cancellation (ANC) technology is not built into hearing aids because it selectively amplifies and attenuates certain audio frequencies relative to other frequencies to manage background noise. The purpose of this invention is to cancel out sudden, very loud sounds that can damage your hearing due to sudden noises, such as a door slamming, someone using a hammer in the house, or someone shouting nearby. However, if you go to a concert that is intentionally over-amplified, you will need earplugs or earmuffs.

[0010] As previously mentioned, impulse noises are dangerous to everyone, including hearing aid wearers, and furthermore, protection from such noises occurring in the environment is not adequately addressed by hearing aids. Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, as a prerequisite for limiting potential harm to hearing aid wearers, devices and methods are needed to detect impulse sounds in the immediate environment of the hearing aid. Such devices and methods are preferably optimized to react automatically and very quickly so as to prevent sounds whose waveforms (in terms of volume and loudness as a function of time) are particularly dangerous from reaching the outer ear of the wearer, while interfering as little as possible with the "normal" operation of the hearing aid in the absence of impulse noise. Ideally, the necessary elements can be added or incorporated into the hearing aid, optimizing the comfort and convenience of the user, while minimizing the changes required to the physical housing and operating requirements of the device. [Means for solving the problem]

[0012] The present invention includes methods and systems or devices for reducing the volume of potentially harmful impulse noises that may enter the hearing aid wearer's ears, either in amplified form or by passive transmission.

[0013] In one embodiment, a hearing aid includes a microphone and a processing unit configured to receive sound incident on the hearing aid and send a corresponding microphone output to the processing unit, the processing unit configured to process the microphone output to generate a first processor output that includes a determination of whether the incident sound includes a potentially harmful impulse sound, and to generate a second processor output that includes a processed version of the microphone output.

[0014] In another embodiment, a method of protecting a hearing aid wearer from sudden loud sounds includes receiving an incident sound using a microphone in the hearing aid and sending a corresponding microphone output to a processing unit in the hearing aid, and processing the microphone output using the processing unit to generate a first processor output determined whether the incident sound includes a potentially harmful impulse sound, and generating a second processor output including a processed version of the microphone output.

[0015] A further understanding of the nature and advantages of particular embodiments disclosed herein may be realized by reference to the remaining portions of the specification and the attached drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 illustrates a hearing aid according to some embodiments of the present invention. [Diagram 2] FIG. 1 illustrates the operating principle of an ANC circuit (prior art). [Diagram 3] FIG. 1 shows examples of various configurations of hearing aids (prior art). [Figure 4] FIG. 1 illustrates a method according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Described herein are embodiments of devices and methods for detecting dangerously loud noises and protecting hearing aid wearers with hearing impairments from exposure to dangerously loud noises by using active noise cancellation (ANC) technology.

[0018] FIG. 1 shows a hearing aid 100 according to some embodiments of the present invention. The hearing aid 100 includes audio signal processing circuitry in a processing unit 104, receives an input signal from a microphone 102, and sends an output signal to a speaker 107 housed in an earpiece 106. For clarity, only a single microphone (102) is shown, but depending on the type of hearing aid, there may be multiple microphones, which allows the hearing aid to determine the direction from which sound is received. For example, it may determine that a person is speaking in front of the wearer and amplify that sound more appropriately than sounds coming from the side of the wearer. In the remainder of this disclosure, a single microphone will be described. However, the operating principles of the system and related considerations also apply to embodiments including multiple microphones.

[0019] Although the microphone 102, earpiece 106, and speaker 107 are not necessarily different from the microphones and speakers present in currently widely used hearing aids, the processing unit 104 includes circuitry configured to address the problem of potentially harmful impulse noise. To achieve this, it has a sufficiently fine time resolution and a sufficiently high dynamic range to determine whether such noise is present and provide a corresponding positive or negative first output. The unit 104 also provides a second output that includes a processed version of the microphone output signal (usually a frequency-dependent amplified version).

[0020] The present invention uses adjustable (active) sound vents as one type of response to determining that a potentially harmful impulse sound is present. In some embodiments, the hearing aid 100 has at least one active sound vent. For simplicity, the embodiment of FIG. 1 shows only one such vent 112. As explained in the Background, a vent is an opening in the earpiece of the hearing aid that allows environmental sounds to be transmitted directly to the ear without going through electronic signal processing. Thus, in some embodiments of the present invention, if the first output from the processing unit 104 indicates that a potentially harmful impulse noise is present, the hearing aid can respond by automatically closing any active sound vents that are present. By blocking the direct path of the passively entering and passing sound, the intensity of that "passive" sound can be significantly attenuated before it reaches the ear canal.

[0021] The present invention uses ANC technology as another type of response to determining that a potentially harmful impulse sound is present. An embodiment that enables this response includes ANC circuitry within the processing unit of the hearing aid.

[0022] Consider the case where the hearing aid 100 shown in FIG. 1 receives a sound characterized by an exemplary waveform 108 shown in the form of an envelope of amplitude versus time. The upper positive half of the waveform and the lower negative half of the waveform would touch in the absence of noise, but in this more realistic case, there is clearly low amplitude background noise. The waveform 108 includes two parts of a "true" signal, meaning a signal containing the sound the hearing aid wearer wants to hear, superimposed on the background noise, and one burst of impulse noise occurring in the period between these two signal parts. The ANC circuit in the processing unit 104 operates to send a signal to the speaker 107, which then generates an output sound having a waveform 110 with an envelope substantially devoid of a central peak corresponding to the impulse noise. Throughout this disclosure, the term "substantially devoid" is used to mean that the volume of the corresponding sound is significantly reduced (at least 50%). An ideal reduction would be 100%, meaning that the noise peaks are completely cancelled, but in practice a reduction of 50% or more would provide a significant improvement in terms of potential harm to the hearing aid wearer, who may barely hear the sound at all. How this reduction can be achieved is described further below.

[0023] FIG. 2 illustrates how a conventional ANC circuit works to completely, or more realistically, substantially “cancel” an undesirable sound. For simplicity, consider the hypothetical case where a microphone receives a pure single-frequency sound and generates a corresponding electrical waveform 201 that characterizes that sound. The ANC circuit then responds by generating an “inverse” or “anti-noise” electrical waveform 203 with an inverted phase polarity. The combination of the two waveforms is sent to a speaker, which responds by generating a sound waveform that represents the combination. In the ideal case, the sound waveform will be a flat line that does not change over time, as shown at 205, but more realistically, because noise cancellation may not be perfect, it may be a low amplitude waveform such as 207 that contains components at the input frequency.

[0024] In audio devices prior to this invention, active noise cancellation is a feature that the user selects by performing a deliberate action, such as pressing a button on the headphones. In such devices, all ambient noise outside the headphones is suppressed to some degree.

[0025] Conventional implementations do not address the specific problem of impulse noise cancellation. In the present invention, circuitry within the hearing aid's processing unit (104 in FIG. 1) is specially designed to automatically detect and respond to impulse noises that are particularly dangerous to the hearing aid wearer, and the circuitry works in conjunction with other standard hearing aid components to cancel (or physically block) such noises fast enough to minimize the risk of damage to hearing.

[0026] In many embodiments, the circuitry (including, of course, the ANC circuitry, if present) must be able to handle very high noise levels, well above 80 dBA, a typical threshold used to distinguish between safe and dangerous volume levels. For example, impact sounds generated by fireworks or guns can reach peak volume values ​​of 140-150 dBA. This may impose high dynamic range requirements on the processing unit electronics.

[0027] In many embodiments, the electronics of the processing unit must be able to track signals that rise from normal, safe volume levels to dangerously high levels in a very short time, typically less than half a second, which places correspondingly stringent requirements on time resolution. Meeting such requirements successfully addresses the goal of automatically protecting the hearing aid wearer by electronically canceling or mechanically blocking noise waveforms characteristic of potentially harmful impulse noises.

[0028] In some embodiments, the criteria used by the circuitry in the processing unit to determine that a received noise is potentially harmful (it should be understood that in some embodiments, multiple criteria can be used, so in general, the determination of potential harm can be based in part or in full on the criteria as described in this disclosure) is whether the unit receives a microphone output corresponding to a microphone that detects a dangerously loud noise level. In other words, if a microphone detects an incident sound that includes a portion characterized by a noise waveform that exceeds a volume threshold that is considered dangerously high, the processing unit determines that a corrective action needs to be taken in response, such as activating an ANC circuit or closing an active vent, or both. The volume threshold is, for example, 120 dBA. In some cases, other thresholds may be appropriate depending on the environment in which the hearing aid is used.

[0029] In some embodiments, the criterion used by the circuitry in the processing unit to determine that a received noise is potentially harmful is whether the unit receives a microphone output corresponding to the microphone detecting an impulsive sound that may rise very quickly from a relatively safe level at a very high rate and reach a dangerously high level, even if it may remain at that high level for a very short time. If the rate of increase is, for example, 5 dBA / sec from an initial level of 80 dBA, that combination may activate the ANC circuit. In different situations, different users, or different hearing aid settings, different combinations of initial level and rate of increase values ​​may be more appropriate threshold triggers for ANC operation.

[0030] In yet other embodiments, the criteria used may be a combination of volume level and rate of volume increase, where exceeding either threshold may reliably determine that there is potential harm.

[0031] FIG. 3 shows examples of various configurations of commonly used hearing aids. Some contain the microphone, processing unit, and speaker in a single housing, the majority of which is behind the pinna of the ear, with an audio guide tube hooked in front so that it can be placed in the ear canal. Others have the part containing the microphone, processing unit, and speaker tucked into the fold of the pinna, again with an audio guide tube leading to the ear canal. Still other devices have the microphone and processing unit located in one place, for example to be hooked behind the ear, but the speaker is either at the entrance to the ear canal or separately located in the ear canal. The present invention essentially relies on incorporating ANC circuitry designed for the intended impulse noise cancellation application in the processing unit, and can be implemented in any of these various device configurations.

[0032] It should be noted that depending on the settings of the hearing aid, only certain frequencies of sound can be specifically amplified. Other frequencies can be transmitted at nominal volume, unamplified, or attenuated. Depending on the device, some sounds can passively pass through the hearing aid device and enter the ear canal. While one object of the present invention is to attempt to cancel potentially harmful noises that are electronically processed by passing through the hearing aid, another object of the present invention is to attempt to cancel potentially harmful noises that passively enter the ear canal.

[0033] FIG. 4 illustrates a method 400 according to some embodiments of the present invention. In step 402, a microphone in the hearing aid receives the ambient sound and sends its output to a processing unit in the hearing aid. In step 403, the processing unit processes the microphone output. In step 404, the processing unit determines whether the sound received by the microphone contained potentially harmful noise based on one or more predefined criteria. If the result is negative, the processing unit sends a processed version of the microphone output, usually with frequency-dependent amplification, to a speaker in the earpiece of the hearing aid, so that in step 405 the speaker generates and outputs a sound without harmful noise (because there was no noise in the ambient sound). On the other hand, if the result of the determination in step 404 is positive, at least one of two paths is followed. In a particular embodiment, if the hearing aid is provided with one or more controllable vents, the method proceeds to step 406, where the vents are automatically closed, thereby partially or completely preventing potentially harmful noise passively present in the hearing aid from exiting the earpiece. Although in the figure, step 407 is shown as occurring after step 406, it should be understood that for simplicity, step 407, in which the speaker outputs a processed version of the microphone output, can occur simultaneously with step 406 or before step 406.

[0034] If only the path from step 404 to steps 406 / 407 is followed (which is the case if there is no ANC functionality), then the speaker output at step 407 will contain potentially harmful sounds. In other embodiments, where ANC functionality is present, the method may advantageously follow the path to steps 408, 409, and 410 simultaneously with the path of 406 / 407. This "ANC" path is now described.

[0035] In step 408, the ANC circuitry is activated to generate an anti-noise waveform, as described above with reference to Figure 2. Then, in step 409, the processing unit output to the hearing aid speaker is a constellation including a processed version of the anti-noise waveform and a processed version of the noise waveform, the former expected to cancel, or at least significantly reduce, the amplitude of the latter. In step 410, the speaker provides an audible output that is substantially free of sounds corresponding to portions of the incident sound characterized by the noise waveform.

[0036] Of course, in embodiments where active vents are not present, only the path from step 404 through steps 408-410 can be followed. In preferred embodiments, where both active vents and ANC functionality are present, noise cancellation and vent closure can be performed to more comprehensively address the problem of potentially harmful noise.

[0037] It should be appreciated that method 400, or variations thereof, as shown in Figure 3 and described above, may be applied to many different types of hearing aids in common use. Examples of predetermined criteria that may be applied in step 404 to determine whether a waveform profile is potentially harmful and therefore whether either noise cancellation using ANC circuitry or vent closure (or both) should be triggered are also described above.

[0038] Embodiments of the present invention offer significant advantages over the prior art in this field in addressing impulse noise, and in doing so reliably and conveniently without relying on the active participation of the hearing aid wearer. Retrofitting currently available hearing aids to implement the inventive concepts described herein should be quite feasible.

[0039] Although described above with reference to specific embodiments, these specific embodiments are merely illustrative and not limiting.

[0040] Any suitable programming language may be used to implement the routines of particular embodiments, including C, C++, Java, assembly language, etc. Different programming techniques may be used, such as procedural or object-oriented. The routines may be executed on a single processing device or multiple processors. Although steps, operations, or computations may be presented in a particular order, this order may be changed in different particular embodiments. In some particular embodiments, multiple steps shown sequentially herein may be executed simultaneously.

[0041] Certain embodiments may be implemented in a computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, system, or device. Certain embodiments may be implemented in the form of control logic in software or hardware or a combination of both. The control logic, when executed by one or more processors, is operable to perform what is described in certain embodiments.

[0042] Particular embodiments may be implemented using programmed general-purpose digital computers and / or using application specific integrated circuits, programmable logic devices, field programmable gate arrays, optical, chemical, biological, quantum or nano-engineered systems, components and mechanisms. In general, the functions of particular embodiments may be achieved by any means known in the art. Distributed, networked systems, components and / or circuits may be used. Communication or transfer of data may be by wire, wireless, or any other means.

[0043] It will also be understood that one or more of the elements shown in the drawings / figures may be implemented in a more separate or integrated manner, or in some cases deleted or rendered inoperative, as may be useful depending on the particular application. It is also within the spirit and scope of the present invention to implement a program or code that may be stored on a machine-readable medium to cause a computer to perform any of the methods described above.

[0044] A "processor" includes any suitable hardware and / or software system, mechanism, or component that processes data, signals, or other information. A processor may include a system including a general-purpose central processing unit, multiple processing units, dedicated circuits for implementing functions, or other systems. Processing need not be limited to a geographic location, nor need it have time constraints. For example, a processor may perform its functions in "real-time," "offline," "batch mode," etc. Portions of processing may be performed at different times and in different locations by different (or the same) processing systems. Examples of processing systems may include servers, clients, end-user devices, routers, switches, network storage, etc. A computer may be any processor in communication with a memory. The memory may be any suitable processor-readable storage medium, such as a random access memory (RAM), a read-only memory (ROM), a magnetic or optical disk, or other non-transitory medium suitable for storing instructions for execution by a processor.

[0045] As used in this description and in the claims that follow, the words "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Also, as used in this description and in the claims that follow, the meaning of "in" includes "in" and "on," unless the context clearly dictates otherwise.

[0046] Thus, while specific embodiments have been described herein, it will be understood that modifications, various changes, and freedom of substitution are contemplated in the foregoing disclosure, and that in some cases, some features of a specific embodiment may be used without the corresponding use of other features without departing from the scope and spirit of the described embodiment. Accordingly, many modifications may be made to adapt a particular situation or content to the substantial scope and spirit. [Explanation of symbols]

[0047] 100 Hearing aids 102 Microphone 104 Processing Unit 106 Earpiece 107 Speaker 108 waveform 110 waveform 112 Sound Vent 201 Electrical Waveform 203 Electrical Waveform

Claims

1. A hearing aid, A microphone and A processing unit; Including, the microphone is configured to receive incident sound entering the hearing aid and to send a corresponding microphone output to the processing unit; the processing unit is configured to process the microphone output to determine whether the incident sound includes a potentially harmful impulsive sound and to generate a processor output including a processed version of the microphone output. A hearing aid characterized by:

2. 2. The hearing aid of claim 1, wherein the determination is based in part on whether the incident sound received by the microphone includes a portion characterized by a noise waveform that meets predetermined criteria.

3. 3. The hearing aid of claim 2, wherein the predetermined criteria includes exceeding a first threshold volume level.

4. 4. The hearing aid of claim 3, wherein the first threshold volume level is 120 dBA.

5. 3. The hearing aid of claim 2, wherein the predetermined criteria includes exceeding a first threshold rate of rise starting from a volume level equal to a second threshold volume level.

6. 6. The hearing aid of claim 5, wherein the first threshold rate of rise is 5 dBA / sec and the second threshold volume level is 80 dBA.

7. 3. The hearing aid of claim 2, wherein the processing unit includes an active noise cancellation (ANC) circuit that is automatically activated in response to a determination that the incident sound received by the microphone includes a portion characterized by a noise waveform that satisfies the predetermined criterion and is operable to generate an anti-noise waveform that is included in the processor output.

8. 3. The hearing aid of claim 2, further comprising one or more controllable vents configured to automatically close in response to a determination from the processing unit that the incident sound received by the microphone includes a portion characterized by a noise waveform that satisfies the predetermined criterion.

9. further comprising an earpiece including a speaker; a housing containing the microphone and the processing unit configured to be worn behind the pinna of a user's ear or tucked into the fold of the pinna; The earpiece is configured to be placed in or at the entrance of an ear canal of an ear; audible output generated by the speaker is delivered from the earpiece directly to a user's ear canal; A hearing aid according to claim 1 .

10. 1. A method for protecting a hearing aid wearer from sudden loud noises, the method comprising: receiving incident sound using a microphone within the hearing aid and sending a corresponding microphone output to a processing unit within the hearing aid; processing the microphone output using the processing unit to generate a first processor output determined by whether the incident sound includes a potentially harmful impulse sound and to generate a second processor output comprising a processed version of the microphone output; The method according to claim 1, further comprising:

11. 11. The method of claim 10, wherein the determination is based in part on whether the incident sound received by the microphone includes a portion characterized by a noise waveform that meets predetermined criteria.

12. 12. The method of claim 11, wherein the predetermined criteria includes exceeding a first threshold volume level.

13. 13. The method of claim 12, wherein the first threshold volume level is 120 dBA.

14. 12. The method of claim 11, wherein the predetermined criteria includes exceeding a first threshold rate of rise beginning at a volume level equal to a second threshold volume level.

15. 15. The method of claim 14, wherein the first threshold rate of rise is 5 dBA / sec and the second threshold volume level is 80 dBA.

16. 12. The method of claim 11, wherein the processing includes automatically activating an active noise cancellation (ANC) circuit in the processing unit in response to determining that the incident sound received by the microphone includes a portion characterized by a noise waveform that satisfies the predetermined criteria, the ANC circuit operative to generate a corresponding anti-noise waveform.

17. generating an audible output corresponding to the second processor output using a speaker in an earpiece of the hearing aid; the second processor output includes a combination of a signal corresponding to the noise waveform and a signal corresponding to the anti-noise waveform, and the audible output produced by the speaker and potentially heard by a wearer of the hearing aid is substantially free of sounds corresponding to portions of the incident sound characterized by the noise waveform.

17. The method according to claim 16.

18. a housing containing the microphone and the processing unit is mounted behind the pinna of a user's ear or tucked into the folds of the pinna; The earpiece is positioned within the ear canal or at the entrance to the ear canal, the audible output generated by the speaker is delivered directly from the earpiece to a user's ear canal; 20. The method according to claim 17 .

19. 12. The method of claim 11, further comprising automatically closing one or more controllable vents in response to determining that the incident sound received by the microphone includes a portion characterized by a noise waveform that satisfies the predetermined criteria.

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