Acoustic vowel space size and perceived speech tempo

“Females speak faster than males.” Although several studies have proved this stereotype to be wrong [Byrd (1994)], it is still a widespread belief in many languages and within both genders. The interesting question is why. Two findings are particularly relevant regarding this stereotype: First, females reveal a greater acoustic vowel space than males [Hillenbrand et al. (1995)]. Second, a stimulus with a moving f0-contour is perceived as faster than the same stimulus with a monotonous contour [Lehiste (1976)]. From that, we might propose that if a dynamic f0 contour triggers the perception of a faster speaking rate, then a larger acoustic vowel space might have the same effect. The reason for female speakers being perceived as speaking at a faster tempo, then, is that they traverse on average a larger acoustic vowel space within the same time-frame than male speakers do. Furthermore, we could also expect a relationship between vowel space size and perceived speech tempo within the same gender. A perception test was conducted with temporally aligned stimuli from 56 female speakers who vary in their vowel space sizes. Results reveal a significant positive correlation between vowel space size and perceived tempo (r = 0.36, p < 0.001).