Examination of Energy Based Voice Activity Detection Algorithms for Noisy Speech Signals

Abstract

This paper examines the behavior of two different energy-based voice activity detector (VAD) algorithms for noisy input signals. The examined detectors use time-domain methods to find speech boundaries. Time-domain short time energy features and/or zero-crossing rate of speech signals are used to evaluate the performance of the methods. In the first stage of both algorithms, time-domain short-time energy (STE) features are calculated for each speech segment. Then energy ratios and threshold values are used to detect any voicing activity of speech signals. The decision threshold value is calculated by evaluating the average STE of an initial silence period. The effectiveness of the selected methods is tested for clean and noisy speech samples. The methods are tested using the noisy speech signals under different SNR levels. The results indicated that both methods achieve a reasonable accuracy as low as an SNR value nearly 0dB with a slowly decreasing performance. But, under 0dB SNR, both methods lose their effectiveness against noisy conditions.