Input Stimuli for Obtaining Frequency Responses of Automatic Gain Control Hearing Aids

1989 ◽  
Vol 32 (1) ◽  
pp. 189-194 ◽  
Author(s):  
David A. Preves ◽  
Lucille B. Beck ◽  
Edwin D. Burnett ◽  
Harry Teder
Keyword(s):  
Frequency Response ◽  
Hearing Aids ◽  
Input Signal ◽  
Pure Tone ◽  
Automatic Gain Control ◽  
Broad Band ◽  
Gain Control ◽  
Response Curves ◽  
Frequency Responses ◽  
Band Noise

Developing a family of frequency response curves for AGC types of hearing instruments using swept pure tones at varying input levels often produces erroneous results. This problem is caused by exceeding the threshold for activating the AGC circuit at some frequencies but not at other frequencies during the pure-tone sweep, thereby producing a different frequency response from that which would be obtained with a complex input signal such as speech-shaped noise. This measurement artifact may be minimized by ensuring that the threshold for activating the AGC circuit is either always exceeded or never exceeded during the development of a frequency response curve. Three input signals are compared for developing a family of frequency responses for an AGC hearing aid: (1) swept pure tone, (2) swept pure tone with bias tone added, and (3) shaped broad-band noise. The shaped broad-band noise appears to be the input signal of choice.

Performance of New Hearing Aids Using the ANSI S3.22–1976 Standard

1982 ◽  
Vol 47 (4) ◽  
pp. 376-382 ◽  
Author(s):  
Thomas H. Townsend ◽  
Clifford C. Olsen
Keyword(s):  
Hearing Aids ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Test Apparatus

One hundred new hearing aids were tested to determine their compliance with ANSI S3.22–1976 specifications. Thirty-four models representing eight manufacturers were included. Estimates of the test equipment's accuracy were utilized as required by the standard to correct the tolerances permitted for the 11 measurements made. Results revealed that 68% of the instruments tested met all specifications, when the accuracy of the test apparatus was accounted for, while 11% fewer hearing aids passed all tests when it was excluded. No greater than a 10% difference was found in the performance of various types of aids, such as automatic gain control, directional, linear, or nondirectional.

Optimization of a slow-acting automatic gain control system for use in hearing aids

1991 ◽  
Vol 25 (3) ◽  
pp. 171-182 ◽  
Author(s):  
Brian C. J. Moore ◽  
Brian R. Glasberg ◽  
Michael A. Stone
Keyword(s):  
Control System ◽  
Hearing Aids ◽  
Automatic Gain Control ◽  
Gain Control

Variability of Gain Versus Frequency Characteristics in Hearing Aids

1967 ◽  
Vol 10 (2) ◽  
pp. 377-383 ◽  
Author(s):  
Roger N. Kasten ◽  
Stephen H. Lotterman ◽  
Sally G. Revoile
Keyword(s):  
Frequency Response ◽  
Hearing Aids ◽  
Hearing Aid ◽  
Frequency Characteristics ◽  
Response Curves ◽  
Discrete Frequency ◽  
The Mean ◽  
Frequency Curves

Full-on gain versus frequency response curves were obtained from ten different hearing aid models using 15 samples of each model. A mean curve and the range of responses from 20 discrete frequency points were plotted for each model along with the manufacturer’s published curve at full-on gain values. While about half of the models tested showed good intragroup consistency, the variability of gain characteristics for the remaining models was large. The mean gain versus frequency curves of the sample aids differed from those published by the manufacrurer for about half of the models tested.

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