The NP speech activity detection algorithm

This paper describes a new algorithm, the NP algorithm, for detecting speech signals of varying quality and gain levels. NP operates in the frequency domain and renders speech/no-speech decisions based on a signal-to-noise ratio (SNR) derived from a sorted power spectrum. In addition to the SNR estimates, a spectral whitening process and an estimate of the variance in the ratio of the signal power to total energy are also used to identify and reject signals that are stationary or nearly stationary The key features of this algorithm are: the detection is based on a single FFT; decisions are independent of the signal gain; the process has 3 dB/octave processing gain from the transform; and frequency domain processing permits the exploitation of the signal structure.