A voice activity detector using the chi-square test

This paper proposes a voice activity detector (VAD) that makes the speech/noise classification by applying the statistical chi-square test to each frame. It also uses a continuous update of the background noise estimate. The speech is first enhanced using a noise reduction system, with noise estimates also obtained with the help of the chi-square test. The noise-reduced signal is decomposed into sub-bands, and the chi-square test is used again in another form to compare the observed signal distribution to the estimated noise distribution. If the chi-square test determines that they are close, the frame is declared to be noise, otherwise speech. The performance of this VAD was found to be significantly superior to several benchmark VAD, with accuracies above 89% even at a SNR of 0 dB, which is up to 25% better than the others.