Analog dereverberation system
AssigneeBell Telephone Laboratories, Incorporated
InventorDonald Henry Nash
Life of this patent
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Abstract
Room reverberation characteristic of monaural systems is removed, in accordance with the principles of this invention, by employing two microphones at the sound source and by manipulating the signals of the two microphones to develop a single nonreverberant signal. Both early echoes and late echoes in the signal received by each microphone are removed by manipulating the signals of the two microphones in separate frequency bands of the signal. Corresponding frequency bands of the two signals are co-phased and added and the magnitude of each resulting frequency band is modified in accordance with a computed phase difference average between the corresponding frequency bands. The modified frequency bands are combined, thereby forming the nonreverberant signal.
Claims9
An analog dereverberation system comprising:
- first filter/delay means for developing a first plurality of variably delayed analog bandpass signals in response to a first input signal and a control signal;
- second filter/delay means for developing a second plurality of delayed analog bandpass signals in response to a second input signal;
- a plurality of correlator means responsive to corresponding signals of said first and second pluralities of bandpass signals for developing a plurality of nonreverberant bandpass signals and for developing said control signal;
- and
- means for adding said plurality of nonreverberant bandpass signals to form a single analog nonreverberant signal.
An analog dereverberation system responsive to signals from two microphones comprising:
- filter/delay means responsive to the signals of said two microphones for time shifting the signal of one of said two microphones with respect to the signal of the other of said two microphones under control of a shift control signal and for developing a plurality of bandpass signals from the time shifted signal of said one of said two microphones and from the signal of the other of said two microphones;
- means for adding corresponding bandpass signals of said one microphone and said other microphone to develop added bandpass signals;
- means responsive to said plurality of bandpass signals for developing said time shift control signal and a gain control signal;
- means for effecting the amplitudes of said added bandpass signals in accordance with said gain control signal to develop gain modified bandpass signals;
- and
- means for combining said gain modified bandpass signals to form a single nonreverberant signal.
Dependencies are inferred from the claim text.