Telephone line equalization for robust speech recognition

The authors describe a transparent in-line system for equalizing telephone channels for a bank by phone application. The existing voice recognition equipment is speaker dependent for security reasons and is particularly sensitive to linear distortion that may be introduced by the telephone channel. Channel estimates are derived using spectral estimates computed from a pre-determined utterance made on each call. These estimates are then used to construct a filter which can compensate for the distortion. The system is implemented in real time on a Motorola 56001 chip