Patent Application
20110142269
The present invention relates to hearing aids. In particular, the present invention pertains to switches for changing settings on a hearing aid having a digital signal processor (“DSP”) for processing the microphone sensed signal.
Hearing aids are electrical devices having a microphone to receive sound and convert the sound waves into an electrical signal, some sort of amplification electronics which increase and often modify the electrical signal, and a speaker (commonly called a “receiver” in the hearing aid industry) for converting the amplified output back into sound waves that can be better heard by the user. The electronic circuitry is commonly powered by a replaceable or rechargeable battery. In most modern hearing aids, an analog electrical output from the microphone is converted into a digital representation, and the amplification electronics include a DSP acting on the digital representation of the signal.
Hearing aids have long included settings which can be user-controlled to change the audio response parameters of a hearing aid, generally allowing the user to optimize the hearing aid for different varieties of listening situations. For instance, a first setting may be for normal listening situations, a second setting may be for listening in noisy environments, a third setting may be for listening to music, and a fourth setting may be for use with a telephone. Typically, the user can cycle through these settings (also called parameter sets or programs) using a switch on the hearing aid. Examples of the parameters that are adjusted between the various settings include volume, frequency response shaping, and compression characteristics.
The most common type of switch for cycling through hearing aid settings is a mechanical push button switch. The mechanical switch is usually located either on the body or the faceplate of the hearing aid in a position which the user can touch with a finger while wearing the hearing aid.
Mechanical switches, though simple, normally reliable and fairly low-cost, have their drawbacks. Due to the small size of the push button, the user may not always realize that the button has been pushed. To clearly indicate to the user that the push button has been activated, most hearing aids generate an audible tone. Despite the generated tone, however, most users still have a hard time locating the push button on the hearing aid because the push button is relatively small compared to the user's fingers. This drawback makes hearing aids with a push button hard to operate, especially for elderly users. As hearing aids become smaller and are positioned further in the user's ear canal, manipulation of the mechanical switch becomes more and more difficult for most users.
Additionally, push buttons located on the body or the faceplate of a hearing aid are susceptible to sweat and debris that can lead to switch failure. While switches are normally reliable, they include moving parts that can and do fail. Also, while the push button may be small relative to a user's finger tips, it still adds to the size of the hearing aid, thus making the hearing aid more visible and unattractive. While mechanical switches are relatively low cost, such as on the order of a few dollars, they still do contribute to the overall cost of the product.
Separate from the hearing aid industry, acoustic power-on switches for operating 120 Volt AC, plug-in appliances (lights, televisions, etc.) are well known in the U.S. by virtue of the advertising campaign of Joseph Enterprises for the CLAPPER device. See, for instance, U.S. Pat. Nos. 3,970,987, 5,493,618 and 5,615,271. In the most common CLAPPER device, the user brings his or her hands together in two loud claps, and the sound waves for the claps are received by a microphone and analyzed to assess when a user has intended to turn the appliance on or off.
Similarly, a wide variety of voice-activated switches have arisen which respond to vocal commands. Voice-activated commands have well documented problems in terms of cost, size, processing capabilities and accuracy.
While voice-activated and CLAPPER switches may be useful for appliances and other devices, similar types of switches have not found widespread use in hearing aids. Hearing aid users would often be unwilling to clap twice loudly or speak a command each time the user wants to change settings, including in the wide variety of locations where the hearing aid might be in use (such as during a music concert, in a quiet auditorium, etc.). Moreover, hearing aid users generally desire their hearing aid use to be as inconspicuous as possible. The costs of adding these types of switches to a hearing aid (not only monetary, but also processing/battery costs and size costs) have not been found commercially acceptable.
Several attempts have been made to replace the mechanical hearing aid switch with a processor-based switch based upon the microphone input but which avoids audible actuation. For instance, U.S. Pat. No. 6,748,089 to Harris et al. discloses a hearing aid switch which is intended to be actuated by the user placing his or her hand in a cupped position over the ear to attenuate the incoming audio signal. This solution has not found marketplace acceptance, likely due to its reliability. Audio signals witnessed by hearing aids naturally change amplitude on a moment to moment basis. It is very difficult to distinguish in a hearing aid processor when such amplitude changes occur due to hand placement over the ear from when such amplitude changes occur due to signal source variations.
As another example, U.S. Pat. No. 7,639,827 to Bachler discloses a hearing aid switch which is intended to be actuated by the user again placing his or her hand in a cupped position over the ear, this time to drive the hearing aid amplification circuit into an unstable, oscillation (feedback) condition. However, unstable oscillation often causes a loud whistling tone in hearing aids which users seek to avoid. Further, most users have many natural gestures and hand movements which place their hands adjacent their ears, and also place other items (telephones, hats, etc.) adjacent their ears. Additional complications arise in that users have differently shaped ears and different hearing aid placements (microphone locations) in their ears, meaning that the microphone response to a given input is not identical from user to user both located in the same room.
A good hearing aid switch should both avoid false positives, i.e., switching when the user has not intended to initiate the switch, and avoid false negatives, i.e., not recognizing each time the user has attempted to initiate the switching action. Until hearing aids are developed which can silently sense the brain waves of the user to determine when the user desires a switch between settings, better solutions are needed.
The present invention is a switch actuated by a user by hand movement relative to a wearer's ear. The switch utilizes pressure/sound clues from a filtered input signal. Most importantly, the pressure/sound clues are related to a signature hand movement relative to the user's ear. The preferred signature hand movement involves cupping of the hand and patting the ear meatus at least one time to generate a compression wave commonly thought of as a soft “clap”, “pop” or “thud” due to the way the user's hand mates with ear geometry and seals a volume of air in the concha bowl. Other preferred signature hand movements include two motions, such as placing or wiping the hand over the ear followed by a cupped-hand pat on the ear, or two repeated cupped-hand pats on the ear. The switch algorithm can also utilize feedback cues from coefficients in the internal adaptive feedback FIR filter. The preferred signature hand movements are effectively silent to others in the vicinity of the hearing aid wearer. The signature hand pressure clues can be accurately distinguished from the wide variety of other sounds and pressure waves encountered by the hearing aid in normal use, preventing false positives. The signature hand pressure clues can be accurately identified and reproducibly learned for a wide variety of users, preventing false negatives.
While the above-identified drawing figures set forth preferred embodiments, other embodiments of the present invention are also contemplated, some of which are noted in the discussion. In all cases, this disclosure presents the illustrated embodiments of the present invention by way of representation and not limitation. Numerous other minor modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention.
The DSP 21 has parameter settings 54, also known as programs, which assist a hearing aid user in providing different processing characteristics for different types of listening environments and different types of acoustic input 14. The programs 54 may be able to adjust the gain in each frequency band 22 or may adjust other DSP characteristics such as volume, frequency response shaping, noise control and compression characteristics. To change from one set of parameter settings to another set of parameter settings in the hearing aid 10, the hearing aid 10 has some sort of user controlled switch 56.
In most prior art hearing aids, the user controlled switch is a physical push button located either on the body or on the faceplate of the hearing aid. Physical push buttons operate by opening or closing an electrical contact from its normal state. When the physical push button is pressed, the hearing aid responsively switches to the next available set of parameter settings.
Although the number of parameter settings available in hearing aids varies, a typical hearing aid 10 might have three or four sets of parameter settings. For example, a first set may be for normal listening situations, a second set may be for listening in noisy environments, a third set may be for listening to music, and a fourth set may be for use with a telephone. After a user reaches the last available parameter setting, the next push of the physical push button resets the hearing aid 10 back to the first parameter setting.
While the hearing aid 10 represented in
The present invention involves a hearing aid 10 and a method of changing settings 54 on that hearing aid 10. At a minimum, the hearing aid 10 includes a microphone 12 positioned on, around or in the user's ear, and also includes a DSP 21 acting on the microphone signal. It may be possible to locate the microphone 12 behind the user's ear meatus 58 (ear geometry identified in
Further understanding of the invention can be obtained by review of the signals of
The preferred implementation was performed in the APT hearing aid available from IntriCon Corporation of Arden Hills, Minn., which is an in-the-canal (but not sealing the canal 62) hearing aid 10. It is believed that similar results would be achieved over a wide variety of hearing aids, particularly if the hearing aid is an in-the-ear or in-the-canal hearing aid, and that slightly modified results might be obtainable in behind-the-ear implementations.
Based upon a review of numerous cupped pat, low pass band signals such as those of
As shown by the differences in
In general terms, the same general signature characteristics will be witnessed across a wide variety of different people, all performing a cupped hand ear-pat 66 in different ways, using a wide variety of hearing aids in a wide variety of environmental acoustic situations. While the present invention uses the term “cupped” to refer generally to the hand shape which some wearers will use to create the signature compression wave event which activates the switch 56, the user's hand 68 need not necessarily be curved into a cup shape, so long as the act of striking the ear 64 creates the “popping” of air compression of sufficient magnitude to be identified as a switching event in the hearing aid 10. Most users will be familiar with this distinction in terms of the difference between clapping one's hands together and slapping one's hands together. For many wearers, the “clap” or “pop” can be created with two or more fingers pressed together in a “salute” hand shape, positioned so the two or more fingers line up to make contact all around the periphery of the concha bowl. Like clapping, it is very difficult to create the “clap” or “pop” with only a single finger. Alternatively, the “clap” or “pop” can be created by patting the open palm over the concha bowl. What is important is that the “clap” or “pop” is created, much more than the particular hand shape or hand position used to create the “clap” or “pop”. Similarly, while the volume of the “clap” or “pop” sound needs to be above a threshold in order to switch, the existence of the “clap” or “pop” is more important than the force with which the ear 64 is struck; a soft tap or pat 66 which achieves the “clap” or “pop” can be identified more easily than a hard “slap”, and much more easily than a slap which does not cover the concha bowl 60. Further, the volume of the “clap” or “pop” is only important as witnessed by the hearing aid, not by others in the room; the preferred signature hand motions 66 are sufficiently soft that they are largely or entirely unheard by anyone other than the hearing aid wearer.
The signature compression wave event shown in
The distinguishing nature of the signature signal produced with the present invention is further seen when comparing what would otherwise be considered potential false positives, i.e., other sounds possibly encountered in daily life which could be misinterpreted as a switching hand movement.
Another type of potential false positive signal comes from wind noise. Wind noise can produce a large amplitude signal in the low pass range. However, similar to the much lower conversation signal shown in
Further understanding of the nature of the signature characteristics of the cupped hand ear-pat event 66 is gained with reference to
A further point of the cupped hand ear-pat involves the dissipation of sound energy as a function of travel distance. Namely, sound level is generally considered to drop about 6 dB each time the distance from the source of the sound doubles. The microphone 12 of the hearing aid 10 will be within an inch or two of the user's hand 68 where it contacts the ear 64, witnessing the sound/pressure wave in the 85 to 120 dB SPL range. Others in the room are typically 30-300 inches away, meaning that the SPL of those people from the cupped hand ear-pat will be 30 to 45 dB less than at the hearing aid 10. The user's hand 68 itself may further muffle this sound output. The low frequency energy created by the cupped hand ear-pat, though creating a dramatic signature in the low frequency filtered output of the hearing aid microphone 12, is not objectionable and seldom even heard by others in the room. The hearing aid user, by making a hand gesture which is less intrusive than trying to shoo away a fly, can generate a signature causing switching of the hearing aid 10.
Further understanding of the preferred embodiment of the present invention is provided through the state diagram of
As an initial step, the signature pattern recognition algorithm has a “ready” state 70, which generally occurs whenever the hearing aid 10 is in standard use without drastic signal changes. The cupped hand ear-pat detection algorithm can only begin from the “ready” state 70. As will be explained, starting the cupped hand ear-pat detection algorithm but failing to complete the switching will place the algorithm in a “noisy” state 72, from which it must time out through a time period of relative quiet before returning to the “ready” state 70. As long as conditions are within the quiet threshold 74, the quiet counter increases 76 until a quiet counter limit is met 78 and the algorithm returns to a “ready” state 70. In the current algorithm using the low frequency band 22a of the APT DSP 21, the test to leave the “noisy” state 72 and return to the “ready” state 70 is a time period of a 100 ms when the voltage of the low pass signal remains within normal levels, e.g., corresponding to an acoustic signal of less than about 97 dB SPL. During the vast majority of hearing aid use, the algorithm is in the “ready” state 70. However, certain events such as wind noise or the pure tone shown in
Assuming the algorithm is in the “ready” state 70, the algorithm begins by attempting to identify the first large negative pulse 80 of the cupped hand ear-pat event 66. The algorithm remains in the “ready” state 70 as long as the signal amplitudes are relatively quiet. In the current algorithm using the low frequency band 22a of the APT DSP 21, the algorithm remains in the “ready” state 70 until a positive or negative amplitude corresponding to over about 100 dB SPL is witnessed (|low pass signal|>100 dB). In the signal shown in
As soon as the signal exceeds this first possible pulse threshold 82, the first state 84 has been reached, and the algorithm starts looking for the large negative pulse 80, beginning a negative pulse countdown 86. In the current preferred algorithm using the low frequency band 22a of the APT DSP 21, the algorithm is looking for a negative pulse 80 corresponding to a sound pressure level equal to or greater than about 106 dB, which occurs within the time period 88 of no longer than 40 ms after reaching the first state 84. With the signal shown in
If a negative pressure pulse 80 equal to or greater than the negative pulse threshold 90 is witnessed, the algorithm checks 92 to verify that the width of the negative pressure pulse 80 is sufficient. In general terms, the minimum width of the negative pressure pulse 80 requires some number of additional readings to be beyond the negative pulse threshold 90. The preferred algorithm thus includes a step 2a 92 searching for at least one additional voltage value corresponding to a sound pressure level beyond the negative pulse threshold 90. In the example of
If the observed negative pressure pulse 80 passes the negative pulse width check 92, then the algorithm leaves the first state 84 to the second state 94, searching for the high pressure pulse 96. Like when searching for the low pressure pulse 80, the high pressure pulse 96 must be witnessed within a certain duration of a positive pulse countdown 98. In the current preferred algorithm using the low frequency band 22a of the APT DSP 21, the algorithm is looking for a positive pulse 96 corresponding to a sound pressure level equal to or greater than about 102 dB, which occurs within the time period 98 of no longer than 11 ms after confirming 92 the negative pulse 80. In the example of
If a positive pressure pulse 96 equal to or greater than the positive pulse threshold 100 is witnessed, the preferred algorithm checks 102 to verify that the width of the positive pressure pulse 96 is sufficient. Like the negative pulse width check 92, the minimum width of the positive pressure pulse 96 requires some number of additional readings to be beyond the positive pulse threshold 100. The preferred algorithm thus includes a step 3102 searching for at least one additional voltage value corresponding to a sound pressure level above the positive pulse threshold 100. In the example of
Once the positive pulse width check 102 is passed, the next step is to establish the peak 104 of the positive pulse 96, which in the example of
Thus, the example signal of
An alternative preferred method of looking for the quick dissipation of the signature signal is to define a time period window off the positive pressure pulse 96 when the signal must be within the dissipated window 110. For instance, the dissipated window 110 could be defined as the time period of 75 to 90 ms after passing the positive pulse width check 102. If the signal is within the dissipated window 110 throughout the 75 to 90 ms time window (and regardless of what the signal does prior to 75 ms after the high pressure pulse 96), the alternative algorithm is completed and considers the program setting switch 56 “closed”.
Upon staying within the dissipated threshold 106 for the adequate duration 112 such that the limit of the dissipated counter is met 116, the signature pattern recognition algorithm has completed 118 its operation and considers the signal to have been created by the signature hand movement 66. The program settings 54 are indexed forward to the next group of settings. A tone is output on the hearing aid 10, which is audible to the hearing aid user but inaudible to others in the room, signifying to the user that the hand motion 66 was successful in switching the hearing aid 10.
The signature pattern recognition algorithm needs to complete switching of the hearing aid 10 within a reasonable period of time, no more than a few seconds, and preferably within less than one second after the signature hand motion 66. As can be seen in
While the algorithm detailed here identifies the signature hand motion 66 to close the hearing aid switch 56, many changes could be made to the algorithm in accordance with the present invention, and should be changed based upon the hearing aid and conditions with which the algorithm is used. For instance, other hearing aids may set the various thresholds at other values and particularly at other values above 85 dB, and may set the various timers and counters for other durations. The key consideration is to devise a signature hand motion 66 relative to the user's ear 64 which, though effectively silent or unobtrusive to others in the room, creates a sufficiently distinctive signal so as to be identified in the particular hearing aid being used while avoiding both false positives and false negatives.
As a significant alternative to having the values for the first possible pulse threshold 82, the negative pulse threshold 90, and the positive pulse threshold 100 preset, one or all of these thresholds may have a value which is derived based upon the signal. When the signal demonstrates significant noise or volume, either in the low frequency band 22a or elsewhere, the thresholds used in the algorithm can be raised to higher values, and vice versa. When the wearer is in quiet surroundings, the switch 56 can be tripped by a very light cupped hand ear-pat 66. When the wearer is in noisier surroundings, the wearer is willing to make a louder cupped hand ear-pat 66 to trip the switch 56 without fear of disrupting others in the vicinity. Another alternative is to have the sensitivity of the various thresholds set during fitting of the hearing aid, when the particular user can practice the cupped hand ear-pat on his or her own ear and decide how sensitive the switch 56 should be.
Particularly if false positives become an issue for any particular hearing aid or hearing aid user, there are many ways to further modify the algorithm to avoid false positives. As one simple example, the user could be required to complete two or three cupped hand ear-pats, within a duration such as about one second of each other. A preferred multi-pat alternative involves assessing whether a second cupped hand ear-pat occurs within the time window of 100 to 700 ms after the first identified cupped hand ear-pat. The various thresholds of the multi-pat algorithm for identifying the second cupped hand ear-part can be set based upon the witnessed signal from the first cupped hand ear-part, such as requiring both ear pats to be of similar magnitude, requiring the second cupped hand ear-pat to be at higher magnitude than the first, or requiring the second cupped hand ear-pat to be at lower magnitude than the first. The multi-pat alternative is particularly beneficial if the user happens to have sound/pressure waves in their daily routine that mimic the signature created by a single ear-pat. For instance, for some wearers with the hearing aid 10 in their left ear, slamming their car door shut could produce false positives, leading such users to prefer a multi-pat algorithm. Alternatively, the signature pattern recognition algorithm may be set up so that if there is one pat on the user's ear 64, the parameter setting 54 will change one way, whereas if there are two pats on the user's ear 64, the parameter setting 54 will change a different way. As another example, the introduction of the user's hand 68 adjacent the ear 64 changes the feedback characteristics in the FIR filter 42, and the FIR filter coefficients can be monitored to verify that the feedback characteristics have changed. By requiring the detection of both the abnormal change in the external feedback path 40 and the input signal generated by the abnormal magnitude of pressure, the device will be more robust and less prone to erroneous parameter setting switches. As a third example, the cupped hand ear-pat 66 could be combined with another distinctive hand motion that can be sensed by the hearing aid microphone 12, such as wiping one's hand 68 away from the ear 64 after completing the cupped hand ear-pat 66.
As an alternative or in conjunction with any of these previously described embodiments, it may be beneficial to perform analysis which is outside the low frequency band. While the most easily recognizable signature pattern from the cupped hand ear-pat 66 is believed to occur in the low frequency band, it likely has artifacts in other frequency bands, such as in the 250-500 Hz band. As significantly, other potential false positives likely have artifacts in other, higher frequency bands. If false positives or false negatives cannot be ruled out by easy analysis of the low frequency band, additional information from higher frequency bands can be used to obtain higher certainty in the switching decision.
All the embodiments of this invention perform the parameter switching normally done by a push button, without an actual physical push button. By obviating the need of a physical push button, the device size and cost can be reduced while improving reliability. Also the user actions that instigate the switching in this invention involve large hand motions. Therefore, there is no need for fine finger dexterity that may be difficult or inconvenient.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
The present application is a continuation-in-part of U.S. application Ser. No. 12/539,702 entitled SWITCH FOR A HEARING AID, filed Aug. 12, 2009, which is based on and claims the benefit of U.S. provisional patent application Ser. No. 61/088,033, filed Aug. 12, 2008. The contents of both U.S. application Ser. No. 12/539,702 and U.S. provisional patent application Ser. No. 61/088,033 are hereby incorporated by reference in entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61088033 | Aug 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12539702 | Aug 2009 | US |
| Child | 13030828 | US |
