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US 5,271,057 AGranted
Audio processing system for teleconferencing system
AssigneeBell Communications Research, Inc.
InventorsEric J. Addeo, Joseph J. Desmarias, Gennady Shtirmer
Life of this patent
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Abstract
An audio processing system (100) for use in a teleconferencing system (10) utilizes complementary comb filters (42, 52, 220, 320) in combination with an echo suppressor (210, 310) and/or a frequency scaler (60, 120) to substantially improve acoustic stability margin and reduce far-end talker echo.
Claims8
A teleconferencing system comprising
- a first station including first microphone means and first speaker means,
- a second station remotely located from the first station and including second microphone means and second speaker means,
- a first audio channel connecting said first microphone means with said second speaker means and a second audio channel connecting said second microphone means with said first speaker means,
- first and second comb filters having complementary pass and stop bands located in said first and second channels, respectively, for attenuating echoes which are signals coupled between said first speaker means and said first microphone means and between said second speaker means and said second microphone means,
- a first echo suppressor connected to said first microphone means for selectively blocking said first channel when no speech is present at said first station and for opening said first channel when speech is present at said first station,
- a second echo suppressor connected to said second microphone means for selectively blocking said second channel when no speech is present at said second station and for opening said second channel when speech is present at said second station,
- and means connected to said second and first echo suppressors for selectively activating said first and second comb filters, respectively.
4 more elements
A teleconferencing system comprising
- a first station including a first microphone and a first speaker,
- a second station including a second microphone and a second speaker,
- a first audio transmission channel for connecting said first microphone with said second speaker and a second audio transmission channel for connecting said second microphone with said first speaker,
- a fist echo suppressor connected to said first microphone for switching said first channel between a passing state and a blocking state,
- a second echo suppressor connected to said second microphone for switching said second channel between a passing state and a blocking state,
- a first comb filter located in said second channel,
- means responsive to said first echo suppressor for activating said first comb filter when said first channel is in a passing state,
- a second comb filter located in said first channel, and
- means responsive to said second echo suppressor for activating said second comb filter when said second channel is in a passing state, said first and second comb filters having complementary pass and stop bands.
6 more elements
Dependencies are inferred from the claim text.