Electrical audio signal processing systems and devices – Monitoring/measuring of audio devices – Testing of hearing aids
Reexamination Certificate
1999-10-06
2004-09-14
Isen, F. W. (Department: 2644)
Electrical audio signal processing systems and devices
Monitoring/measuring of audio devices
Testing of hearing aids
C381S083000
Reexamination Certificate
active
06792114
ABSTRACT:
BACKGROUND OF THE INVENTION
Pending patent application Ser. No. 09/081,474, filed May 19, 1998 and entitled “Feedback Cancellation Improvements” is incorporated herein by reference.
1. Field of the Invention
The present invention relates to apparatus and methods for integrated hearing aid performance measurement and initialization.
2. Description of the Prior Art
In general, hearing aid performance measurements, whether on the production line or in the individual wearer's ear, have used an external test system that generates the test signal and analyzes the response. The measurement of the frequency response of a hearing aid in the ear, for example, typically requires the use of external signal generating and measurement equipment (Egolf, D. P., Tree, D. R., and Feth, L. L., 1978, “Mathematical predictions of electroacoustic frequency response of in situ hearing aids”, J. Acoust. Soc. Am., Vol. 63, pp 264-271; Bade, P. F., Engebretson, A. M., Heidbreder, A. F., and Niemoeller, A. F., 1984, “Use of personal computer to model the electroacoustics of hearing aids”, J. Acoust. Soc. Am., Vol. 75, pp 617-620; Sanborn, P-E, 1998, “Predicting hearing aid response in real ears”, J. Acoust. Soc. Am., Vol. 103, pp 3407-3417). Measurements of the feedback path from the receiver back to the hearing aid microphone also have required the use of external equipment (Egolf, D. P., Howell, H. C., Weaver, K. A., and Barker, S., 1985, “The hearing aid feedback path: Mathematical simulations and experimental verification”, J. Acoust. Soc. Am., Vol. 78, pp 1578-1587), as does the determination of the maximum output signal level (Revit, L. J., 1994, “Using coupler tests in the fitting of hearing aids”, in Strategies for Selecting and
Verifying Hearing Aid Fittings
, ed. by M. Valente, New York: Thieme Medical Publishers).
A conventional digital hearing aid is shown in
FIG. 1A
(prior art). Input sound signal
152
is converted into an audio signal by microphone
154
. Hearing aid processor
156
is a digital signal processor (analog to digital conversion at the input and digital to analog conversion at the output are omitted for clarity). The processed audio signal is amplified by amplifier
158
and converted back into a sound signal
162
by receiver
160
. Conventional digital hearing aids like hearing aid
110
use digital signal processing for the run time system, but still rely on conventional measurement equipment for measuring the hearing aid response and setting the processing parameters. Most digital hearing aids do not contain a programmable DSP circuit, but instead use a dedicated processor that can only perform the run time processing operations (Schweitzer, C., “Development of digital hearing aids”, Trends in Amplification, Vol 2, pp 41-77). These hearing aids are therefore incapable of performing any measurements, calibration, or parameter initialization.
An example of a conventional hearing aid test system
100
is illustrated in
FIG. 1B
(prior art). The hearing aid
110
to be evaluated is placed in a test box
102
. The input to hearing aid
110
is an acoustic test signal
109
from loudspeaker
108
, also contained in test box
102
. Hearing aid
102
is configured to perform the desired signal processing function, such as linear gain or multiband compression. The hearing aid output is an acoustic signal that is then piped to acoustic coupler
114
via a piece of tubing
113
. The acoustic coupler consists of a microphone
118
placed at the end of a cavity
116
. An external computer
104
controls the generation of test signal
109
and acquires and processes the microphone response
120
. Display
116
displays test results. A commercial hearing aid test system that conforms to this basic design is the Fonix 6500, manufactured by Frye Electronics, Inc, Tigard, Oreg. 97223.
For independently performing measurements, the digital hearing aid must be able to accept a program for generating a test signal and recording the response as well as accept the program for the run time processing. A need remains in the art for apparatus and methods to enable a hearing aid to measure its own performance characteristics and to use those measurements to set its processing parameters.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide apparatus and methods to enable a hearing aid to measure its own performance characteristics and to use those measurements to set its processing parameters.
In addition to providing digital processing of the audio signal being amplified to compensate for the hearing loss, the programmable DSP circuit of a hearing aid according to the present invention is also used to measure the characteristics of the hearing aid on the production line or fitted to the individual ear. Such a hearing aid might perform measurements such as maximum output signal level, distortion, or the response characteristics of the microphone or receiver. By using the signal processing system described herein, these and other tests can be performed all or in part by the hearing aid under test. A test program is loaded into the hearing aid and the tests are performed. Then the program used for the run time amplification, along with any processing parameters set during the tests, is loaded into the hearing aid memory.
REFERENCES:
patent: 5999631 (1999-12-01), Porayath et al.
patent: 6366863 (2002-04-01), Bye et al.
PCT Application No. PCT/US99/06682, entitled, “Feedback Cancellation Improvements,” Nov. 25, 1999 as International Publication No. WO 99/60822.
PCT Application No. PCT/US99/06642, entitled, “Apparatus and Methods for Combining Audio Compression and Feedback Cancellation in a Hearing Aid,” published Oct. 7, 1999 as International Publication No. WO 99/51059.
Revit, Lawrence J. “Using Coupler Tests in the Fitting of Hearing Aids,”Strategies for Selecting and Verifying Hearing Aid Fittings, Ed. Michael Valente, pp. 64-87.
Schweitzer, Christopher. “Development of Digital Hearing Aids,” Trends in Amplification 2(2), New York: Woodland, 1997, pp. 40-77.
Sanborn, Eric. “Predicting Hearing Aid Response in Real Ears,” J. Acoust. Soc. Am. 103(6), Jun. 1998, pp. 3407-3417.
Egolf, David P., Henry C. Howell, Kim A. Weaver, and D. Steven Barker. “The Hearing Aid Feedback Path: Mathematical Simulations and Experimental Verification,” J. Acoust. Soc. Am. 78(5), Nov. 1985, pp. 1578-1587.
Bade, Priscilla F., A. Maynard Engebretson, Arnold F. Heidbreder, and Arthur F. Niemoeller. “Use of a Personal Computer to Model the Electroacoustics of Hearing Aids,” J. Acoust. Soc. Am. 75(2), Feb. 1984, pp. 617-620.
Egolf, David P. “Mathematical Predictions of Electroacoustic Frequency Response ofIn SituHearing Aids,” J. Acoust. Soc. Am. 63(1), Jan. 1978, pp. 264-271.
Kates James Mitchell
Lindemann Eric
Melanson John Laurence
Bales Jennifer L.
GN ReSound A/S
Isen F. W.
Macheledt Bales & Heidmiller LLP
McChesney Elizabeth
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