Experiments on Voice Qualities of Vowels in Males and Females and Correlation With Acoustic Features

An investigation was performed to find acoustic parameters that control voice-qualities of natural speech. Twelve utterances of the vowel [a] by six males and six females were used as speech stimuli, and four terms that express voice-qualities were employed for similarity judgments in paired comparisons. Listeners were asked to rate similarity on a five-point scale, and a correlation analysis was made between the similarity data and such acoustic parameters as fundamental frequency and the frequencies of the first three formants. "Pitch sensation" was found to correlate closely with the fundamental frequency, but no significant correlations were observed between each of these acoustic measures and other voice-qualities. The results varied with the listeners; every listener seemed to use his/her own acoustic cues, which may differ from those of other listeners, in judging the similarity of each voice-quality.