Telephonic communications – Special services – Conferencing
Patent
1993-08-11
1995-07-18
Dwyer, James L.
Telephonic communications
Special services
Conferencing
379390, 379392, 379406, H04M 356, H04M 120
Patent
active
054349125
ABSTRACT:
Our audio processing system for use in teleconferencing systems includes a microphone, receiver, and substantially the same comb filter and frequency scaler at each station for reducing acoustic echo and increasing the margin of acoustic stability. The comb filters and frequency scalers cooperate with one another in that the frequency scalers each induces a shift in frequency which corresponds to the peak-to-trough spacing of the transfer function of the comb filters. Our audio processing system may also include auxiliary echo suppressors for reducing acoustic echo and increasing the margin of acoustic stability in systems having high and low transmission delays. Other devices may be employed for reducing noise and smoothing out the operation of individual components in the system. Since the comb filters employed at each station are not complementary, but are substantially the same, our audio processing system can mitigate the effects of acoustic instability and echo in point-to-point and multipoint audio processing systems. Furthermore, since each station utilizes substantially the same equipment, the need for equipment negotiation between stations and equipment changes prior to a conferencing session is obviated.
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Boyer David G.
Jalali Ali L.
Shtirmer Gennady
Bell Communications Research Inc.
Dwyer James L.
Hong Harry S.
Suchyta Leonard Charles
Yeadon Loria B.
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