The influence of vocal frequency and intensity on the perception of speech rate: Natural speech samples as stimuli

Previous studies by the authors found, using masked speech samples, that the perception of speech rate was influenced by both vocal frequency and intensity. The study reported here replicated the previous one but used unmasked, or natural, speech stimuli and examined the effects of speaker gender. Using one speech sample each from a male and female speaker, three levels of frequency and intensity were factorially combined to produce nine stimuli for each speaker. The actual speech rate of each stimulus was 150 wpm The 18 stimuli were randomly ordered with each preceded by a standard stimulus. Twenty-nine judges rated each stimulus, relative to the standard, on four 7-point, unipolar scales: speech rate, pitch, loudness, and duration. The results indicate that the perceptions of speech rate were positively related to frequency but not intensity. Judgments of pitch and loudness were positively related to frequency and intensity, respectively, and judgments of duration were inversely related to frequency. Finally, the influence of frequency on perceived speech rate differed for the male and female speaker.