Relative importance of formant and whole-spectral cues for vowel perception

Three psycho-acoustical experiments were carried out to investigate relative importance of formant frequency and whole spectral shape as cues for vowel perception. Four types of vowel-like signals were presented to eight listeners. The mean responses for stimuli including both formant and amplitude-ratio feature were quite similar to those for the stimuli including only formant peak feature. Nonetheless reasonable vowel changes were observed in responses for stimuli including only amplitude-ratio feature. The perceived vowel changes were also observed even for stimuli including neither of these features. The results suggested that perceptual cues were involved in various parts of vowel spectrum.