Abstract: A hearing aid is permanently adjusted to match prescribed amplification characteristics at predetermined frequencies. A single channel filter (24) includes three identical filter stages (60, 62, and 64) that are optionally cascaded in series. Each of the filter stages (60, 62, and 64) exhibits a frequency response curve having a first corner frequency (36) below which the magnitude of the response curve approaches a predetermined minimum value, a second corner frequency (38) above which the magnitude of the response curve approaches a maximum value, and a predetermined gain in magnitude between the minimum and maximum values.
Type:
Grant
Filed:
November 3, 1992
Date of Patent:
April 11, 1995
Assignee:
Auditory System Technologies, Inc.
Inventors:
Kenneth R. Miller, Lynn F. Fuller, James C. Taylor, Robert D. Frisina, Joseph P. Walton
Abstract: A signal processing circuit is incorporated into an audio reproducing device for suppressing noise while preserving distinctive features of speech. A noise detecting circuit includes a low pass filtering circuit (12) and a level detector (14). An output signal (C) from the detecting circuit controls a variable high pass filtering circuit (20) to attenuate a range of low frequencies of an input signal (A) proportional to the detected level of noise. The variable high pass filtering circuit exhibits a family of variable response curves (22, 24, and 26) that vary in slope below a common cut-off frequency (28) that is below a range of frequencies that convey a majority of second formant transitions between consonants and vowels.
Type:
Grant
Filed:
March 31, 1992
Date of Patent:
February 8, 1994
Assignee:
Auditory System Technologies, Inc.
Inventors:
Joseph P. Walton, Kenneth R. Miller, James C. Taylor, Lynn F. Fuller, Robert D. Frisina