The paper describes a hands-free speech recognition technique based on acoustic model adaptation to reverberant speech. In hands-free speech recognition, the recognition accuracy is degraded by reverberation, since each segment of speech is affected by the reflection energy of the preceding segment. To compensate for the reflection signal, we introduce a frame-by-frame adaptation method, adding the reflection signal to the means of the acoustic model. The reflection signal is approximated by a first-order linear prediction from the preceding frame, and the linear prediction coefficient is estimated by a maximum likelihood method by using the EM algorithm, which maximizes the likelihood of the adaptation data. Its effectiveness is confirmed by word recognition experiments on reverberant speech.
['Tetsuya Takiguchi', 'Masafumi Nishimura']
Acoustic model adaptation using first order prediction for reverberant speech