Supplementary material from "Human voice pitch measures are robust across a variety of speech recordings: methodological and theoretical implications"

Fundamental frequency (f_o), perceived as voice pitch, is the most sexually dimorphic, perceptually salient and intensively studied voice parameter in human nonverbal communication. Thousands of studies have linked human f_o to biological and social speaker traits and life outcomes, from reproductive to economic. Critically, researchers have used myriad speech stimuli to measure f_o and infer its functional relevance, from individual vowels to longer bouts of spontaneous speech. Here, we acoustically analysed f_o in nearly 1000 affectively neutral speech utterances (vowels, words, counting, greetings, read paragraphs and free spontaneous speech) produced by the same 154 men and women, aged 18–67, with two aims: first, to test the methodological validity of comparing f_o measures from diverse speech stimuli and second, to test the prediction that the vast inter-individual differences in habitual f_o found between same-sex adults are preserved across speech types. Indeed, despite differences in linguistic content, duration, scripted or spontan­­eous production and within-individual variability, we show that 42–81% of inter-individual differences in f_o can be explained between any two speech types. Beyond methodological implications, together with recent evidence that inter-individual differences in f_o are remarkably stable across the lifespan and generalize to emotional speech and nonverbal vocalizations, our results further substantiate voice pitch as a robust and reliable biomarker in human communication.