A practical question in a Fourier transform coding of speech signals is to what accuracy their amplitude and phase spectra have to be represented without perceptible distortions. In this paper we are concerned with the audibility of these special types of quantization noise signals produced by coding Fourier amplitude and phase. From our psychophysical experiments, we found that the relative perceptual importance of phase and magnitude spectra in the Fourier transform coding is strongly dependent on the fundamental frequency of the vowel sounds and the window size used in the short time Fourier analysis.

Keywords: Speech coding, Auditory masking.