Echo suppressor for a speech input dialogue system

Details Echo suppressor for a speech input dialogue system Echo suppressor for a speech input dialogue system

1998-01-22

2000-10-17

Chan, Wing F.

Telephonic communications

Echo cancellation or suppression

704233, H04M 100

Patent

active

061343226

ABSTRACT:
In an echo suppressor and a method for the operation thereof in a speech input system, particularly suited for use in speech input systems having extremely long echo paths (approximately 50 ms), an input request of the speech recognition system as well as the incoming speech signal (which has been corrupted by the input request) are fast-Fourier transformed, and the transformed signals are divided into a number of sub-bands in order to estimate corresponding sub-band echo signals. This occurs with individual adaptive filter stages that utilize the NLMS algorithm. Due to the division into sub-bands and a reduction of the number of these sub-bands, the calculating outlay is minimized and the sampling rate can be reduced. The calculating procedure in the estimating of the echo signal part is thus reduced. After estimating the echo signal for the individual sub-bands, the original signal is restored as a superimposition of the individual echo signal components, and the echo signal restored in this way is subtracted from the corrupted speech signal, so that only a pure speech signal is supplied to the feature extraction stage of the speech recognition system.

REFERENCES:
patent: 5852661 (1999-11-01), Chen
patent: 5978763 (1999-11-01), Bridges
"Cancelling of Synthetic Speech for a Real-time Speech Dialogue System," Nagata et al., Proceeding of the Acoustical Society, vol. 1-21 (1992) pp. 145-146.
"Echo Cancelling in Speech Recognition Systems," Pacifici et al., European Conference on Speech Communication and Technology, Madrid, Sep. 1995, pp. 149-152.
"Kompensation akustischer Echos in Frequenzteilbandern," Kellermann, Frequenz, vol. 39, No. 7/8 (1985) pp. 209-215.

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