COMPARISON BETWEEN SUBBAND AND FULLBAND NLMS FOR IN-CAR AUDIO COMPENSATION AND HANDS-FREE SPEECH RECOGNITION

This paper deals with audio compensation in the car environ- ment for the development of a hands-free spoken dialogue sys- tem with barge-in functionalities. While in a preliminary work we investigated the problem, given an interfering radio signal to compensate, here we focus only on the compensation of speech audio generated by a text to speech synthesizer. The latter one is a more difficult signal to manage, as speech is colored and non stationary or quasi stationary and this degrades the performance of the AEC if a simple NLMS is used. In this paper we will introduce a Subband Acoustic Echo Cancellation (SAEC) for compensating the synthetic prompt speech and we will compare it with a Fullband Acoustic Echo Cancellation (FAEC) demon- strating the good effectiveness in terms of speed of convergence, robustness against noise and computational complexity. The sys- tem performance are being measured in terms of Word Error Rate % (WER) by recognizing isolated and connected digits.