Acoustic differences between voiced and whispered speech in gender diverse speakers

Whispered speech is a naturally produced mode of communication that lacks a fundamental frequency. Several other acoustic differences exist between whispered and voiced speech, such as speaking rate (measured as segment duration) and formant frequencies. Previous research has shown that listeners are less accurate at identifying linguistic information (e.g., identifying a speech sound) and speaker information (e.g., reporting speaker gender) from whispered speech. To further explore differences between voiced and whispered speech, acoustic differences were examined across three datasets (hVd, sVd, and ʃVd) and three speaker groups (ciswomen, transwomen, cismen). Consistent with previous studies, vowel duration was generally longer in whispered speech and formant frequencies were shifted higher, although the magnitude of these differences depended on vowel and gender. Despite the increase in duration, the acoustic vowel space area (measured either with a vowel quadrilateral or with a convex hull) was smaller in the whispered speech, suggesting that larger vowel space areas are not an automatic consequence of a lengthened articulation. Overall, these findings are consistent with previous literature showing acoustic differences between voiced and whispered speech beyond the articulatory change of eliminating fundamental frequency.