Gay men displayed significantly higher pitch modulation patterns and less breathy voices compared to heterosexual men, with values shifted toward those of heterosexual women

Speech Acoustic Features: A Comparison of Gay Men, Heterosexual Men, and Heterosexual Women. Alexandre Suire, Arnaud Tognetti, Valérie Durand, Michel Raymond & Melissa Barkat-Defradas. Archives of Sexual Behavior, March 31 2020. https://rd.springer.com/article/10.1007/s10508-020-01665-3

Abstract: Potential differences between homosexual and heterosexual men have been studied on a diverse set of social and biological traits. Regarding acoustic features of speech, researchers have hypothesized a feminization of such characteristics in homosexual men, but previous investigations have so far produced mixed results. Moreover, most studies have been conducted with English-speaking populations, which calls for further cross-linguistic examinations. Lastly, no studies investigated so far the potential role of testosterone in the association between sexual orientation and speech acoustic features. To fill these gaps, we explored potential differences in acoustic features of speech between homosexual and heterosexual native French men and investigated whether the former showed a trend toward feminization by comparing theirs to that of heterosexual native French women. Lastly, we examined whether testosterone levels mediated the association between speech acoustic features and sexual orientation. We studied four sexually dimorphic acoustic features relevant for the qualification of feminine versus masculine voices: the fundamental frequency, its modulation, and two understudied acoustic features of speech, the harmonics-to-noise ratio (a proxy of vocal breathiness) and the jitter (a proxy of vocal roughness). Results showed that homosexual men displayed significantly higher pitch modulation patterns and less breathy voices compared to heterosexual men, with values shifted toward those of heterosexual women. Lastly, testosterone levels did not influence any of the investigated acoustic features. Combined with the literature conducted in other languages, our findings bring new support for the feminization hypothesis and suggest that the feminization of some acoustic features could be shared across languages.

Discussion

This study offers an interesting take on the interaction between sexual orientation and acoustic features of speech in a French speaker sample. First, our analysis of different acoustic features revealed well-known patterns of sexual dimorphism in human voices (i.e., F0, F0-SD, jitter, and HNR). Secondly, our findings showed that French homosexual men displayed a more modulated and less breathy voice than French heterosexual men, thus supporting and extending previous studies conducted mostly with English speakers. Our results for the LDA showed that French homosexual men attested a slight but significant vocal feminization when considering speech acoustic features altogether (up to 10.65%), which support the feminization hypothesis. (It is important to note, however, that no overlap was observed between heterosexual and homosexual men vs. heterosexual women.) Lastly, testosterone levels did not mediate the association between vocal patterns and sexual orientation.

Consistent with previous findings in English-speaking populations, no significant differences were observed in mean F0 between French-speaking heterosexual and homosexual men (Gaudio, 1994; Lerman & Damsté, 1969; Munson et al., 2006b; Rendall et al., 2008; Rogers et al., 2001; Smyth et al., 2003). The results did show a difference between homosexual and heterosexual men in intonation, the former displaying higher pitch variations than the latter. The relationship between pitch variations and sexual orientation was previously found in one Dutch (Baeck et al., 2011) and one American-English population (Gaudio, 1994), suggesting that feminized pitch variations might be characteristic of male homosexual speech across languages (but see Levon, 2006). In our study, the average difference in pitch variations reached ~ 4.11 Hz, which is largely above the just noticeable difference for pitch (Pisanski & Rendall, 2011). Hence, our findings suggest that pitch variations could be one of the acoustic correlates of sexual orientation that is used by listeners when they correctly assessed sexual orientation through speech only (Gaudio, 1994; Linville, 1998; Smyth et al., 2003; Valentova & Havlíček, 2013). Further investigations are nevertheless needed to confirm if such a difference in pitch variations between homosexual and heterosexual men is enough to be used as a cue for assessing sexual orientation.

To our knowledge, this is the first study to report an association between men’s vocal breathiness and sexual orientation. Interestingly, vocal breathiness has been suggested to be an important component of vocal femininity in female voices (Van Borsel et al., 2009) and significant relationships to vocal attractiveness have been reported in both sexes (Xu et al., 2013). Although the difference in vocal breathiness between homosexual and heterosexual men is rather low (mean average difference reached ~ 0.80 dB), further research should test whether it is perceptible by listeners to assess male sexual orientation and whether homosexual men’s voices, which are richer in harmonics compared to those of heterosexuals, are perceived as more attractive among homosexual men.

In our study, T-levels did not influence any of the acoustic parameters investigated. The methods to measure T-level and the sample size used in this study were similar to those used in previous studies finding a significant negative link between T-levels and F0 (e.g., Dabbs & Mallinger, 1999; Evans et al., 2008). However, testosterone is a multiple-effect hormone under the influence of numerous biological and environmental factors and pathways. As such, it is generally difficult to correlate T-levels with other biological or behavioral traits, especially with a unique measurement as realized here. Nevertheless, our results might suggest that other underlying processes, different than basal T-level, are involved in vocal differences between homosexual and heterosexual men.

Although our study does not aim to provide an explanation for why vocal differences were found between homosexual and heterosexual men, several biological and social mechanisms can be invoked. For instance, exposure to prenatal testosterone has been suggested to be responsible for the differences between homosexual and heterosexual men on a large range of characteristics such as physiological and behavioral traits including speech characteristics (Balthazart, 2017; Ehrhardt & Meyer-Bahlburg, 1981). Several studies have thus tested whether the 2D:4D ratio (relative length of the second and fourth digits), a proxy of testosterone prenatal exposure differs between homosexual and heterosexual men (Balthazart, 2017; Ehrhardt & Meyer-Bahlburg, 1981). However, there is currently no consensus regarding whether the 2D:4D ratio differs between heterosexual and homosexual men as studies have yielded mixed results (Breedlove, 2017; Grimbos, Dawood, Burriss, Zucker, & Puts, 2010; Rahman & Wilson, 2003; Robinson, 2000; Skorska & Bogaert, 2017; Williams et al., 2000). Regarding social mechanisms, a social imitation of women’s speech peculiarities by homosexual men could also explain the differences observed between homosexual and heterosexual men’s speech characteristics (at least for F0-SD and HNR). The use of more feminine acoustic characteristics by homosexual men could reflect a selective adoption model of opposite-sex speech patterns or a selective use of acoustic features for signaling in-group identity (Pierrehumbert et al., 2004), an ability called “gaydar” (i.e., the detection of homosexuality based on a set of specific cues). Interestingly, a recent study suggests that the acquisition of a distinctive speech style may happen before puberty, as boys aged from 5 to 13 with gender identity disorder (a diagnosis made when a child shows distress or discomfort due to a mismatch between his/her gender identity and his/her biological sex) display distinctive speech features (higher F0 and F2 as well as a misarticulation of/s/) from boys without it (Munson, Crocker, Pierrehumbert, Owen-Anderson, & Zucker, 2015). Because some homosexual men display a greater degree of gender nonconforming behavior (GNC) than others during childhood (Bailey & Zucker, 1995), one could thus hypothesize that the former would be more likely to have a more feminine speech in adulthood than the latter. Further work should investigate the relative importance of the mechanisms underlying homosexual men’s speech.

To conclude, although our study did not aim to test specific hypotheses against a formal theoretical framework to understand the differences between homosexual and heterosexual men’s speech, it provides some new descriptive findings. By examining for the first time native French speakers and some understudied acoustic features (i.e., namely, jitter and HNR), our results indicated that some vocal traits differed between heterosexual and homosexual men (i.e., variations of pitch and vocal breathiness) with values shifted toward heterosexual women’s vocal characteristics. Combined with the literature conducted in other languages, our findings bring new support for the feminization hypothesis (at least for some acoustic features) and suggest that the feminization of some acoustic features could be shared across languages. Further studies are needed to test whether intonation and vocal breathiness are perceptually salient to distinguish homosexual and heterosexual men, and whether overall differences are due to biological and/or sociolinguistic reasons.