Usefulness of phase in human speech perception

Short-time Fourier transform of speech signal has two components: magnitude spectrum and phase spectrum. In this paper, relative importance of short-time magnitude and phase spectra on speech perception is investigated. Human perception experiments are conducted to measure intelligibility of speech tokens synthesized either from magnitude spectrum or phase spectrum. It is traditionally believed that magnitude spectrum plays a dominant role for shorter windows (20-30 ms); while phase spectrum is more important for longer windows (128-256 ms). It is shown in this paper that even for shorter windows, phase spectrum can contribute to speech intelligibility as much as the magnitude spectrum if the shape of the window function is properly selected.