A theory of the evolution of low voice pitch in men suggests that (a) voice pitch is used as an indicator of success in mate competition; (b) pitch is used as an indicator of dominance more for men’s voices than women’s; (c) pitch affects dominance ratings more than attractiveness ratings. While early studies supported these ideas, several subsequent studies have failed to replicate these results with mainly male raters, because of the idea that men’s perceptions affect selection more than women’s do. We tested the extent to which these findings apply to women’s perceptions of the aforementioned characteristics, as well as to other characteristics related to voice pitch and dominance: perceived body size, competitiveness, cooperativeness, socio-economic status, and attractiveness. We manipulated pitch in men’s and women’s voices and tested women’s perceptions thereof. Women chose low voices as belonging to a speaker that is more physically/socially dominant, less cooperative, larger, higher in socio-economic status, and (for men’s voices) more attractive. In contrast to hypotheses of theories on the evolution of low voice pitch in men, pitch had no effect on perceptions of competitiveness, nor did it affect either physical or social dominance ratings more than it affected attractiveness ratings. Surprisingly, pitch affected dominance perceptions of women’s voices more than men’s. Thus, despite previous evidence that some men modify their voices in competitive scenarios, our data are unable to support the idea that this information is used by women to infer dominance related to competitiveness. We contribute to the growing literature that finds no difference in the amount that voice pitch affects dominance and attractiveness ratings or fails to find stronger effects for male than female voices. Our data are consistent with theories that dominance ratings are the result of a general response bias to stimuli varying in pitch. / Thesis / Master of Science (MSc) / Low voice pitch is associated with perceptions of dominance, size, attractiveness, higher socio-economic status, and low cooperativeness. Since men lower their voice pitch in competitive scenarios, we predicted low pitch would be tied to perceptions of competitiveness of the speaker. We manipulated pitch in men’s and women’s voices, and female participants chose which voice they thought belonged to the person who was more physically/socially dominant, competitive, cooperative, larger, higher in socio-economic status, and more attractive. Women chose low voices as being more physically/socially dominant, less cooperative, larger, higher in socio-economic status, and (for male voices only) more attractive than higher voices. Pitch had no effect on perceptions of competitiveness, it did not affect perceptions of dominance for male speakers more than female speakers, neither did it affect perceptions of dominance more than attractiveness. This challenges the idea that low pitch in men evolved to primarily signal success in intrasexual competition.

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Previous experiments have shown that voice pitch (the perception of fundamental frequency and/or corresponding harmonics) is positively associated with women’s voice attractiveness, however all of this research is on women’s speaking voices. Singing is important for the mating success of non-human animals, is cross-culturally universal in humans, and is highly sexualized in many cultures. Thus, singing could contribute to mating success and attraction in humans. First, we investigated whether previous findings, that high voice pitch when speaking predicts women’s voice attractiveness, extend to when women sing. We also examined whether pitch- and rhythm accuracy contribute to women’s singing voice attractiveness. Voice pitch was positively related to women’s singing voice attractiveness as judged by men more than when judged by women, and speaking voice attractiveness was positively related to singing voice attractiveness. Thus, men and women may be reacting to the same indicator of women’s underlying quality (i.e. voice pitch) in both women’s speaking and singing voices, differently. Men may be attracted to high pitch, whereas women may show a weaker relationship, as they tend to be more romantically jealous of women with high pitched voices. Pitch- and rhythm accuracy did not predict women’s singing voice attractiveness. This result can be interpreted in different ways. It could mean that women’s voice pitch may be more important in determining men’s perceptions of their singing voice attractiveness than is their singing ability, or our measures were ill suited to the task. Collectively, these results are the first to show that singing voices are more attractive than speaking voices, people with attractive speaking voices tend to have attractive singing voices, and that singing and speaking voices relate to the same underlying qualities. Thus, singing may be an indicator of mate value and could have played a role in the evolution of sex differences in the voice if our ancestors had similar preferences. / Thesis / Master of Science (MSc)

Music and language are both deeply rooted in our biology, but scientists have given far more attention to the neurological, biological and evolutionary roots of language than those of music. Because of this, and probably partially due to this, the purpose of music, in evolutionary terms, remains a mystery. Our brain, physiology and psychology make us capable of producing and listening to music since early infancy; therefore, our biology and behaviour are carrying some of the clues that need to be revealed to understand what music is “for”. Furthermore, music and language have a deep relationship, particularly in terms of cognitive processing, that can provide clues about the origins of music. Non-verbal behaviours, including voice characteristics during speech, are an important form of communication that enables individual recognition and assessment of the speaker’s physical characteristics (including sex, femininity/masculinity, body size, physical strength, and attractiveness). Vocal parameters, however, can be intentionally varied, for example altering the intensity (loudness), rhythm and pitch during speech. This is classically demonstrated in infant directed speech (IDS), in which adults alter vocal characteristics such as pitch, cadence and intonation contours when speaking to infants. In this thesis, I analyse vocal modulation and its perception in human social interaction, in different social contexts such as courtship and authority ranking relationships. Results show that specific vocal modulations, akin to those of IDS, and perhaps music, play a role in communicating courtship intent. Based on these results, as well the body of current knowledge, I then propose a model for the evolution of musicality, the human capacity to process musical information, in relation to human vocal communication. I suggest that musicality may not be limited to specifically musical contexts, and can have a role in other domains such as language, which would provide further support for a common origin of language and music. This model supports the hypothesis of a stage in human evolution in which individuals communicated using a music-like protolanguage, a hypothesis first suggested by Darwin.

Voices are used as a vehicle for language, and variation in the acoustic properties of voices also contains information about the speaker. Listeners use measurable qualities, such as pitch and formant traits, as cues to a speaker’s physical stature and attractiveness. Emotional states and personality characteristics are also judged from vocal stimuli. The research contained in this thesis examines vocal masculinity, aesthetics and personality, with an emphasis on the perception of prosocial traits including trustworthiness and cooperativeness. I will also explore themes which are more cognitive in nature, testing aspects of vocal stimuli which may affect trait attribution, memory and the ascription of identity. Chapters 2 and 3 explore systematic differences across vocal utterances, both in types of utterance using different classes of stimuli and across the time course of perception of the auditory signal. These chapters examine variation in acoustic measurements in addition to variation in listener attributions of commonly-judged speaker traits. The most important result from this work was that evaluations of attractiveness made using spontaneous speech correlated with those made using scripted speech recordings, but did not correlate with those made of the same persons using vowel stimuli. This calls into question the use of sustained vowel sounds for the attainment of ratings of subjective characteristics. Vowel and single-word stimuli are also quite short – while I found that attributions of masculinity were reliable at very short exposure times, more subjective traits like attractiveness and trustworthiness require a longer exposure time to elicit reliable attributions. I conclude with recommending an exposure time of at least 5 seconds in duration for such traits to be reliably assessed. Chapter 4 examines what vocal traits affect perceptions of pro-social qualities using both natural and manipulated variation in voices. While feminine pitch traits (F0 and F0-SD) were linked to cooperativeness ratings, masculine formant traits (Df and Pf) were also associated with cooperativeness. The relative importance of these traits as social signals is discussed. Chapter 5 questions what makes a voice memorable, and helps to differentiate between memory for individual voice identities and for the content which was spoken by administering recognition tests both within and across sensory modalities. While the data suggest that experimental manipulation of voice pitch did not influence memory for vocalised stimuli, attractive male voices were better remembered than unattractive voices, independent of pitch manipulation. Memory for cross-modal (textual) content was enhanced by raising the voice pitch of both male and female speakers. I link this pattern of results to the perceived dominance of voices which have been raised and lowered in pitch, and how this might impact how memories are formed and retained. Chapter 6 examines masculinity across visual and auditory sensory modalities using a cross-modal matching task. While participants were able to match voices to muted videos of both male and female speakers at rates above chance, and to static face images of men (but not women), differences in masculinity did not influence observers in their judgements, and voice and face masculinity were not correlated. These results are discussed in terms of the generally-accepted theory that masculinity and femininity in faces and voices communicate the same underlying genetic quality. The biological mechanisms by which vocal and facial masculinity could develop independently are speculated.

<p>    </p> <p>Lam, Luchcha. M.S., Purdue University, May 2023. Believe in the Sound You See: The Effects of Body Type and Voice Pitch on the Perceived Audio-Visual Correspondence and Believability of Virtual Characters. Major Professor: Nicoletta Adamo. </p> <p>We examined the effects of body type and voice pitch of virtual characters’ on perceived audio-visual correspondence and believability. For our within-group study, we developed nine experimental conditions using a 3 (body type: ectomorph vs. mesomorph vs. endo- morph body types) × 3 (voice pitch: low vs. medium vs. high fundamental frequency [F0]). We found significant main effects from voice pitch and significant interaction effects between a character’s body type and voice pitch on both the level of perceived audio-visual correspondence and believability of female and male characters. For female characters, we also observed an additional significant main effect from body type and a significant interac- tion effect between the participant’s biological sex and the character’s voice pitch on both perceived audio-visual correspondence and believability. Moreover, the results show that perceived believability is highly correlated to perceived audio-visual correspondence. Our findings have important practical implications in applications where the character is meant to be an emotional or informational guide that requires some level of believability, as the findings suggest that it is possible to enhance the believability of the characters by generating appropriate voices through pitch manipulation of existing voices. </p>