Robust Voice Activity Detection Using Long-Term Signal Variability

Abstract

We propose a novel long-term signal variability (LTSV) measure, which describes the degree of nonstationarity of the signal. We analyze the LTSV measure both analytically and empirically for speech and various stationary and nonstationary noises. Based on the analysis, we find that the LTSV measure can be used to discriminate noise from noisy speech signal and, hence, can be used as a potential feature for voice activity detection (VAD). We describe an LTSV-based VAD scheme and evaluate its performance under eleven types of noises and five types of signal-to-noise ratio (SNR) conditions. Comparison with standard VAD schemes demonstrates that the accuracy of the LTSV-based VAD scheme averaged over all noises and all SNRs is ~6% (absolute) better than that obtained by the best among the considered VAD schemes, namely AMR-VAD2. We also find that, at -10 dB SNR, the accuracies of VAD obtained by the proposed LTSV-based scheme and the best considered VAD scheme are 88.49% and 79.30%, respectively. This improvement in the VAD accuracy indicates the robustness of the LTSV feature for VAD at low SNR condition for most of the noises considered.