Switch for a hearing aid

1. A device, comprising:

at least one microphone for receiving an input sound;

a digital signal processor connected to the microphone for producing a digital processor output signal;

a speaker for converting the digital processor output signal into output sound;

an external feedback path between the speaker and the microphone that can selectively be made abnormal by the device user;

an adaptive internal feedback cancellation system, implemented in the digital signal processor, for continually monitoring and responsively adapting to the abnormal change occurring in the external feedback path;

a detection algorithm, implemented in the digital signal processor, to detect an abnormal change in an external feedback path

at least two parameter settings for adjusting characteristics of the device; and

a feedback path detection switch for switching the device to a different parameter setting in response to output from the detection algorithm wherein the device is a hearing aid.

2. The device of claim 1 , wherein the detection algorithm follows a logical timing sequence comprising logical steps to determine when to indicate the abnormal feedback path detection switch.

3. The device of claim 1 , wherein the abnormal change in the external feedback path occurs when a user cups a user's hand over the device.

4. The device of claim 1 , wherein the abnormal change in the external feedback path occurs when a user cups a user's hand over a user's ear.

5. The device of claim 1 , wherein the adaptive internal feedback cancellation system comprises a finite impulse response filter.

6. A device, comprising:

at least one microphone for receiving an input signal;

a digital signal processor connected to the microphone for analyzing the input signal;

at least two parameter settings for controlling the characteristics of the device;

a pattern recognition algorithm implemented by the digital signal processor for detecting at least one input signal produced when an abnormal pressure wave is generated; and

a pressure wave detection switching system for changing the at least two parameter settings in response to output from the pattern recognition algorithm

wherein the device is a hearing aid.

7. The device of claim 6 , wherein the abnormal pressure wave is generated when a user pats a user's ear with the user's hand.

8. The device of claim 6 , wherein the abnormal pressure wave is generated when a user taps the device with the user's hand.

9. A device, comprising:

at least one microphone an input signal;

digital signal processor connected to the microphone for producing a digital processor output signal, the digital signal processor configured to implement a detection algorithm to detect an abnormal change in an external feedback path;

a speaker for converting the digital processor output signal into an output sound;

an adaptive internal feedback cancellation system for continually monitoring and responsively adapting to changes occurring in an external feedback path;

a pattern recognition algorithm implemented by the digital signal processor for detecting input signals generated when an abnormal pressure wave is generated;

at least two parameter settings for adjusting the characteristics of the device; and

an abnormal feedback path detection switch for switching the device to a next available parameter setting that is responsive to both the detection algorithm and the pattern recognition algorithm

wherein the device is a hearing aid.