Vocal tract length and larynx size determine sex-typical pitch and formants

Evidence

Adult females on average have a shorter vocal tract than males, causing their formants to be about 20% higher in frequency. For the same-shape vocal tract, the similarity principle suggests that all the formants scale together, up or down. Men have a larger larynx and the vocal folds are between 17 and 25 mm in length, as opposed to women’s 12.5 to 17 mm. As a result, the speaking pitch for males tends to be lower, 90 to 150 Hz, as compared to 170 to 220 Hz in females. These are big cues for our pitch-and formant-sensitive brains when deciding whether the speaker is a male or a female. — Eric J. Heller, Why You Hear What You Hear- An…, 1717

Categorization

• DEFINE: The similarity principle (formants scale with tract length) is a key concept in speech acoustics worth defining clearly.
• XREF: connects to: Body size constrains the frequencies animals can vocalize — Almo Farina, Soundscape Ecology: Principles,…, 385