Judgements of a speaker's personality are correlated across differing content and stimulus type

How do voice acoustics affect the perceived trustworthiness of a speaker? A systematic review

Trust is a multidimensional and dynamic social and cognitive construct, considered the glue of society. Gauging someone's perceived trustworthiness is essential for forming and maintaining healthy relationships across various domains. Humans have become adept at inferring such traits from speech for survival and sustainability. This skill has extended to the technological space, giving rise to humanlike voice technologies. The inclination to assign personality traits to these technologies suggests that machines may be processed along similar social and vocal dimensions as human voices. Given the increasing prevalence of voice technology in everyday tasks, this systematic review examines the factors in the psychology of voice acoustics that influence listeners' trustworthiness perception of speakers, be they human or machine. Overall, this systematic review has revealed that voice acoustics impact perceptions of trustworthiness in both humans and machines. Specifically, combining multiple acoustic features through multivariate methods enhances interpretability and yields more balanced findings compared to univariate approaches. Focusing solely on isolated features like pitch often yields inconclusive results when viewed collectively across studies without considering other factors. Crucially, situational, or contextual factors should be utilised for enhanced interpretation as they tend to offer more balanced findings across studies. Moreover, this review has highlighted the significance of cross-examining speaker-listener demographic diversity, such as ethnicity and age groups; yet, the scarcity of such efforts accentuates the need for increased attention in this area. Lastly, future work should involve listeners' own trust predispositions and personality traits with ratings of trustworthiness perceptions.

Voice Quality in Telephone Interviews: A preliminary Acoustic Investigation

OBJECTIVES

To investigate the impact of standardized mobile phone recordings passed through a telecom channel on acoustic markers of voice quality and on its perception by voice experts in normophonic speakers.

METHODS

Continuous speech and a sustained vowel were recorded for fourteen female and ten male normophonic speakers. The recordings were done simultaneously with a head-mounted high-quality microphone and through the telephone network on a receiving smartphone. Twenty-two acoustic voice quality, breathiness and pitch-related measures were extracted from the recordings. Nine vocologists perceptually rated the G, R and B parameters of the GRBAS scale on each voice sample. The reproducibility, the recording type, the stimulus type and the gender effects, as well as the correlation between acoustic and perceptual measures were investigated.

RESULTS

The sustained vowel samples are damped after one second. Only the frequencies between 100 and 3700Hz are passed through the telecom channel and the frequency response is characterized by peaks and troughs. The acoustic measures show a good reproducibility over the three repetitions. All measures significantly differ between the recording types, except for the local jitter, the harmonics-to-noise ratio by Dejonckere and Lebacq, the period standard deviation and all six pitch measures. The AVQI score is higher in telephone recordings, while the ABI score is lower. Significant differences between genders are also found for most of the measures; while the AVQI is similar in men and women, the ABI is higher in women in both recording types. For the perceptual assessment, the interrater agreement is rather low, while the reproducibility over the three repetitions is good. Few significant differences between recording types are observed, except for lower breathiness ratings on telephone recordings. G ratings are significantly more severe on the sustained vowel on both recording types, R ratings only on telephone recordings. While roughness is rated higher in men on telephone recordings by most experts, no gender effect is observed for breathiness on either recording types. Finally, neither the AVQI nor the ABI yield strong correlations with any of the perceptual parameters.

CONCLUSIONS

Our results show that passing a voice signal through a telecom channel induces filter and noise effects that limit the use of common acoustic voice quality measures and indexes. The AVQI and ABI are both significantly impacted by the recording type. The most reliable acoustic measures seem to be pitch perturbation (local jitter and period standard deviation) as well as the harmonics-to-noise ratio from Dejonckere and Lebacq. Our results also underline that raters are not equally sensitive to the various factors, including the recording type, the stimulus type and the gender effects. Neither of the three perceptual parameters G, R and B seem to be reliably measurable on telephone recordings using the two investigated acoustic indexes. Future studies investigating the impact of voice quality in telephone conversations should thus focus on acoustic measures on continuous speech samples that are limited to the frequency response of the telecom channel and that are not too sensitive to environmental and additive noise.

Idiosyncratic and shared contributions shape impressions from voices and faces

Voices elicit rich first impressions of what the person we are hearing might be like. Research stresses that these impressions from voices are shared across different listeners, such that people on average agree which voices sound trustworthy or old and which do not. However, can impressions from voices also be shaped by the 'ear of the beholder'? We investigated whether - and how - listeners' idiosyncratic, personal preferences contribute to first impressions from voices. In two studies (993 participants, 156 voices), we find evidence for substantial idiosyncratic contributions to voice impressions using a variance portioning approach. Overall, idiosyncratic contributions were as important as shared contributions to impressions from voices for inferred person characteristics (e.g., trustworthiness, friendliness). Shared contributions were only more influential for impressions of more directly apparent person characteristics (e.g., gender, age). Both idiosyncratic and shared contributions were reduced when stimuli were limited in their (perceived) variability, suggesting that natural variation in voices is key to understanding this impression formation. When comparing voice impressions to face impressions, we found that idiosyncratic and shared contributions to impressions similarly across modality when stimulus properties are closely matched - although voice impressions were overall less consistent than face impressions. We thus reconceptualise impressions from voices as being formed not only based on shared but also idiosyncratic contributions. We use this new framing to suggest future directions of research, including understanding idiosyncratic mechanisms, development, and malleability of voice impression formation.

Voice-based judgments of sex, height, weight, attractiveness, health, and psychological traits based on free speech versus scripted speech

How do we perceive others based on their voices? This question has attracted research and media attention for decades, producing hundreds of studies showing that the voice is socially and biologically relevant, but these studies vary in methodology and ecological validity. Here we test whether vocalizers producing read versus free speech are judged similarly by listeners on ten biological and/or psychosocial traits. In perception experiments using speech from 208 men and women and ratings from 4,088 listeners, we show that listeners' assessments of vocalizer sex and age are highly accurate, regardless of speech type. Assessments of body size, femininity-masculinity and women's health also did not differ between free and read speech. In contrast, read speech elicited higher ratings of attractiveness, dominance and trustworthiness in both sexes and of health in males compared to free speech. Importantly, these differences were small, and we additionally show moderate to strong correlations between ratings of the same vocalizers based on their read and free speech for all ten traits, indicating that voice-based judgments are highly consistent within speakers, whether or not speech is spontaneous. Our results provide evidence that the human voice can communicate various biological and psychosocial traits via both read and free speech, with theoretical and practical implications.

Comparison of face-based and voice-based first impressions in a Chinese sample

People often form first impressions of others based on face and/or voice cues. This study aimed to compare the first impressions formed under these two cues. First, we compared free descriptions based on face and voice cues and found differences in the content and frequency of the personality words. We then compiled three wordlists used for face-based and voice-based first impression evaluations separately or simultaneously. Second, using these wordlists, we compared face-based and voice-based first impression ratings and found that both had significant intra-rater and inter-rater reliability. However, using the mean of the actors' self-rating and their acquaintance rating as the validity criterion, only the ratings of 'ingenuous' and 'mature' traits in the face-based first impression evaluation were significantly correlated with the validity criterion. Factor analysis revealed that face-based first impression had the dimensions of capability and approachability, while voice-based first impression had capability, approachability and reliability. The findings indicate that stable first impressions can be formed by either face or voice cues. However, the specific composition of impressions will vary between the cues. These results also provide a foundation for studying first impressions formed by an integrated perception of voice and face cues.

Human talkers change their voices to elicit specific trait percepts

The voice is a variable and dynamic social tool with functional relevance for self-presentation, for example, during a job interview or courtship. Talkers adjust their voices flexibly to their situational or social environment. Here, we investigated how effectively intentional voice modulations can evoke trait impressions in listeners (Experiment 1), whether these trait impressions are recognizable (Experiment 2), and whether they meaningfully influence social interactions (Experiment 3). We recorded 40 healthy adult speakers' whilst speaking neutrally and whilst producing vocal expressions of six social traits (e.g., likeability, confidence). Multivariate ratings of 40 listeners showed that vocal modulations amplified specific trait percepts (Experiments 1 and 2), which could be explained by two principal components relating to perceived affiliation and competence. Moreover, vocal modulations increased the likelihood of listeners choosing the voice to be suitable for corresponding social goals (i.e., a confident rather than likeable voice to negotiate a promotion, Experiment 3). These results indicate that talkers modulate their voice along a common trait space for social navigation. Moreover, beyond reactive voice changes, vocal behaviour can be strategically used by talkers to communicate subtle information about themselves to listeners. These findings advance our understanding of non-verbal vocal behaviour for social communication.

The Impact of Stimuli Length and Analytic Method on Auditory 'Gaydar' Research

This research investigates voice-based categorization of speakers' sexual orientation, the so-called 'auditory gaydar', while considering stimuli length and the type of measures assessing gaydar judgments. In Study 1 (N = 80), heterosexual individuals listened to gay and heterosexual male speakers in short (single word), medium (single sentence), or long (two sentences) recordings. Next, they guess the speakers' sexual orientation on a Kinsey-like and binary choice. Participants were overall inaccurate in recognizing gay speakers when gaydar judgments were provided on a binary choice. Gay speakers were rated as more gay on a Kinsey-like scale than their heterosexual counterparts, but only when short and medium recordings were listened to. Study 2 (N = 149) examined gaydar accuracy for both male and female speakers by using the same procedure. Gaydar judgments were overall inaccurate for gay and lesbian speakers. For male speakers, a difference between the perceived sexual orientation of gay and heterosexual speakers emerged when stimuli were long. For female speakers, such a difference occurred only in the short and medium recording conditions. Study 3 (N = 137) examined gaydar judgments for male and female speakers when stimuli length was manipulated as the number of words progressively presented in a sentence: short (article), medium (article + first word), long (sentence) stimulus. Overall, gaydar judgments were inaccurate. Gay and lesbian (vs. heterosexual) speakers tended to be rated as more gay on the Kinsey-like scale in the medium stimulus condition. These findings suggest that gaydar judgments can be influenced by the type of measure and stimuli.

Comparing accuracy in voice-based assessments of biological speaker traits across speech types

Nonverbal acoustic parameters of the human voice provide cues to a vocaliser's sex, age, and body size that are relevant in human social and sexual communication, and also increasingly so for computer-based voice recognition and synthesis technologies. While studies have shown some capacity in human listeners to gauge these biological traits from unseen speakers, it remains unknown whether speech complexity improves accuracy. Here, in over 200 vocalisers and 1500 listeners of both sexes, we test whether voice-based assessments of sex, age, height and weight vary from isolated vowels and words, to sequences of vowels and words, to full sentences or paragraphs. We show that while listeners judge sex and especially age more accurately as speech complexity increases, accuracy remains high across speech types, even for a single vowel sound. In contrast, the actual heights and weights of vocalisers explain comparatively less variance in listener's assessments of body size, which do not vary systematically by speech type. Our results thus show that while more complex speech can improve listeners' biological assessments, the gain is ecologically small, as listeners already show an impressive capacity to gauge speaker traits from extremely short bouts of standardised speech, likely owing to within-speaker stability in underlying nonverbal vocal parameters such as voice pitch. We discuss the methodological, technological, and social implications of these results.

Voice Pathologies and the General Population's Perception

OBJECTIVES

To examine how the general population perceives voice pathology based on subjective qualities.

STUDY DESIGN

Descriptive, cross-sectional, survey-based study.

METHODS

This is an IRB-approved Qualtrics survey on Amazon MTurk for respondents ages 18 and older. Ten subjects with voice pathologies supplied voice recordings of the Rainbow Passage to be assessed by the respondents. Respondents then assessed the voice conditions on perceived qualities of intelligence, leadership ability, and employability. One-way analysis of variance (ANOVA) and Dunnett's multiple comparison test with Sidak correction compared the mean scores of the samples (alpha = 0.05).

RESULTS

A total of 1754 responses were included in the final dataset. The female control voice was scored as more likely to be a Fortune 500 leader as well as more intelligent, friendly, attractive, and employable when compared to the female vocal fry and muscle tension dysphonia (MTD) recordings (P < 0.0001). Conversely, the male MTD was the only male pathology that received a significantly lower score on friendliness, attractiveness, Fortune 500 leader status and employability than the male control (P = 0.0102, P = 0.0007, P = 0.0338, and P = 0.0039, respectively).

CONCLUSIONS

This study demonstrates the more critical appraisal of voice pathologies of female patients compared to their male counterparts. People with voice disorders are perceived as being less successful, a disadvantage to potential leadership and career opportunities.

Speech With Pauses Sounds Deceptive to Listeners With and Without Hearing Impairment

PURPOSE

Communication is as much persuasion as it is the transfer of information. This creates a tension between the interests of the speaker and those of the listener, as dishonest speakers naturally attempt to hide deceptive speech and listeners are faced with the challenge of sorting truths from lies. Listeners with hearing impairment in particular may have differing levels of access to the acoustical cues that give away deceptive speech. A greater tendency toward speech pauses has been hypothesized to result from the cognitive demands of lying convincingly. Higher vocal pitch has also been hypothesized to mark the increased anxiety of a dishonest speaker.

METHOD

Listeners with or without hearing impairments heard short utterances from natural conversations, some of which had been digitally manipulated to contain either increased pausing or raised vocal pitch. Listeners were asked to guess whether each statement was a lie in a two-alternative forced-choice task. Participants were also asked explicitly which cues they believed had influenced their decisions.

RESULTS

Statements were more likely to be perceived as a lie when they contained pauses, but not when vocal pitch was raised. This pattern held regardless of hearing ability. In contrast, both groups of listeners self-reported using vocal pitch cues to identify deceptive statements, though at lower rates than pauses.

CONCLUSIONS

Listeners may have only partial awareness of the cues that influence their impression of dishonesty. Listeners with hearing impairment may place greater weight on acoustical cues according to the differing degrees of access provided by hearing aids.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24052446.

A model for person perception from familiar and unfamiliar voices

When hearing a voice, listeners can form a detailed impression of the person behind the voice. Existing models of voice processing focus primarily on one aspect of person perception - identity recognition from familiar voices - but do not account for the perception of other person characteristics (e.g., sex, age, personality traits). Here, we present a broader perspective, proposing that listeners have a common perceptual goal of perceiving who they are hearing, whether the voice is familiar or unfamiliar. We outline and discuss a model - the Person Perception from Voices (PPV) model - that achieves this goal via a common mechanism of recognising a familiar person, persona, or set of speaker characteristics. Our PPV model aims to provide a more comprehensive account of how listeners perceive the person they are listening to, using an approach that incorporates and builds on aspects of the hierarchical frameworks and prototype-based mechanisms proposed within existing models of voice identity recognition.

The Time Course of Person Perception From Voices: A Behavioral Study

Listeners spontaneously form impressions of a person from their voice: Is someone old or young? Trustworthy or untrustworthy? Some studies suggest that these impressions emerge rapidly (e.g., < 400 ms for traits), but it is unclear just how rapidly different impressions can emerge and whether the time courses differ across characteristics. I presented 618 adult listeners with voice recordings ranging from 25 ms to 800 ms in duration and asked them to rate physical (age, sex, health), trait (trustworthiness, dominance, attractiveness), and social (educatedness, poshness, professionalism) characteristics. I then used interrater agreement as an index for impression formation. Impressions of physical characteristics and dominance emerged fastest, showing high agreement after only 25 ms of exposure. In contrast, agreement for trait and social characteristics was initially low to moderate and gradually increased. Such a staggered time course suggests that there could be a temporo-perceptual hierarchy for person perception in which faster impressions could influence later ones.

Using immersive virtual reality to recreate the synaesthetic experience

Synaesthesia is a condition where people experience unusual sensory or cognitive sensations in response to apparently unrelated stimuli. This paper presents two experiments which aimed to examine whether Virtual Reality (VR) technology can be used to recreate the synaesthetic experience. There is a lack of research in this area, with most studies focussing primarily on synaesthetic colors. Experiment 1 aimed to build on previous research by using not only a traditional color-picker but also VR to capture a more nuanced picture of synaesthetic perception. A multiple case study design was used to examine the experiences of six participants in detail. Data gathering took place via Zoom. During the initial data-gathering session, participants used a color-picker to provide grapheme-color associations. After this session, some of the participants' synaesthetic experiences were recreated using a VR-by-proxy approach. Results indicated that VR is capable of capturing elements of synaesthetic perception that other methods have been unable to, such as texture, small degrees of movement, and 3D structure. Experiment 2 expanded upon these findings by moving beyond the VR-by-proxy approach and asking three participants to recreate their own audiovisual synaesthetic associations in the VR environment. Inductive Thematic Analysis was used to analyze the results of this experiment. The potential of expanding this technique to other forms of perceptual diversity is discussed.

Do Voice-Based Judgments of Socially Relevant Speaker Traits Differ Across Speech Types?

PURPOSE

The human voice is a powerful and evolved social tool, with hundreds of studies showing that nonverbal vocal parameters robustly influence listeners' perceptions of socially meaningful speaker traits, ranging from perceived gender and age to attractiveness and trustworthiness. However, these studies have utilized a wide variety of voice stimuli to measure listeners' voice-based judgments of these traits. Here, in the largest scale study known to date, we test whether listeners judge the same unseen speakers differently depending on the complexity of the neutral speech stimulus, from single vowel sounds to a full paragraph.

METHOD

In a playback experiment testing 2,618 listeners, we examine whether commonly studied voice-based judgments of attractiveness, trustworthiness, dominance, likability, femininity/masculinity, and health differ if listeners hear isolated vowels, a series of vowels, single words, single sentences (greeting), counting from 1 to 10, or a full paragraph recited aloud (Rainbow Passage), recorded from the same 208 men and women. Data were collected using a custom-designed interface in which vocalizers and traits were randomly assigned to raters.

RESULTS

Linear-mixed models show that the type of voice stimulus does indeed consistently affect listeners' judgments. Overall, ratings of attractiveness, trustworthiness, dominance, likability, health, masculinity among men, and femininity among women increase as speech duration increases. At the same time, speaker-level regression analyses show that interindividual differences in perceived speaker traits are largely preserved across voice stimuli, especially among those of a similar duration.

CONCLUSIONS

Socially relevant perceptions of speakers are not wholly changed but rather moderated by the length of their speech. Indeed, the same vocalizer is perceived in a similar way regardless of which neutral statements they speak, with the caveat that longer utterances explain the most shared variance in listeners' judgments and elicit the highest ratings on all traits, possibly by providing additional nonverbal information to listeners.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21158890.

Individual differences in vocal size exaggeration

The human voice carries socially relevant information such as how authoritative, dominant, and attractive the speaker sounds. However, some speakers may be able to manipulate listeners by modulating the shape and size of their vocal tract to exaggerate certain characteristics of their voice. We analysed the veridical size of speakers’ vocal tracts using real-time magnetic resonance imaging as they volitionally modulated their voice to sound larger or smaller, corresponding changes to the size implied by the acoustics of their voice, and their influence over the perceptions of listeners. Individual differences in this ability were marked, spanning from nearly incapable to nearly perfect vocal modulation, and was consistent across modalities of measurement. Further research is needed to determine whether speakers who are effective at vocal size exaggeration are better able to manipulate their social environment, and whether this variation is an inherited quality of the individual, or the result of life experiences such as vocal training.

The effects of theatre-based vocal empowerment on young Egyptian women's vocal and language characteristics

This study investigates the impact of a theatre-based vocal empowerment program on the vocal and language characteristics and the self-perceptions of young bilingual Egyptian women. The program used applied theatre, a dramatic practice that promotes civic action by utilizing improvisational techniques to engage participants in exploring solutions to self-identified community concerns. These techniques supported participants' pursuit of vocal empowerment: the ability to comfortably express their intended content with a clear audible voice, accompanied by the belief that what they had to say was worthwhile. The program was implemented in Alexandria and Aswan, two Egyptian cities in different regions of the country, with distinct socio-economic profiles. Thirty-six young women from Aswan and nineteen from Alexandria participated. The program was facilitated in Arabic, for 90 minutes per day over twelve consecutive days in 2018. Participants in both groups spoke Arabic as a home language and studied English in school settings but differed in their educational experiences and English proficiency. The vocal and language characteristics of each participant were tested in Arabic and English pre- and post- program using a spontaneous speech task and a reading aloud task. Their self-perceptions were evaluated through a vocal self-perception survey. Results indicated that participants responded differently in each city. In Alexandria, participants showed significant improvement in language skills (e.g., mean length of utterance). In contrast, participants in Aswan showed a significant change in fundamental frequency. Overall, the self-surveys indicated that all participants experienced an increased sense of confidence, a stronger belief in self-authorship, and an increased desire to voice their opinions clearly in public; however, there were subtle differences between the groups. In analyzing these results, we conclude that to design effective vocal empowerment outreach programs internationally, it is necessary to consider participants' cultural backgrounds, language diversity, and socio-economic status.

Understanding one's character through the voice: Dimensions of personality perception from Chinese greeting word "Ni Hao"

Previous western studies revealed a two-dimensional model (valence and dominance) in voice impressions. To explore the cross-cultural validity of this model, the present study recruited Chinese participants to evaluate other people's personality from recordings of Chinese vocal greeting word "Ni Hao". Principal Component Analysis (PCA) with Varimax Rotation and Parallel Analysis was used to investigate the dimensions underlying personality judgments. The results also revealed a two-dimensional model: approachability and capability. The approachability dimension was similar to the valence dimension reported in a previous study. It indicated that the approachability/valence dimension has cross-cultural commonality. Unlike the dimension of dominance which was closely related to aggressiveness, the dimension of capability emphasized the social aspects of capability such as intellectuality, social skills, and tenacity. In addition, the acoustic parameters that were used to infer the personality of speakers, as well as the relationship between vocal attractiveness and the personality dimensions of voice, were also partially different from the findings in Western culture.

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 spontan--eous 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.

Linking voice pitch to fighting success in male amateur mixed martial arts athletes and boxers

Whereas voice pitch is strongly linked to people's perceptions in contexts of sexual selection, such as attractiveness and dominance, evidence that links voice pitch to actual behaviour or the formidability of a speaker is sparse and mixed. In this registered report, we investigated how male speakers' voice pitch is linked to fighting success in a dataset comprising 135 (amateur) mixed martial arts and 189 (amateur) boxing fights. Based on the assumption that voice pitch is an honest signal of formidability, we expected lower voice pitch to be linked to higher fighting success. The results indicated no significant relation between a fighter's voice pitch, as directly measured before a fight, and successive fighting success in both mixed martial arts fighters and boxers.

Listeners' perceptions of the certainty and honesty of a speaker are associated with a common prosodic signature

The success of human cooperation crucially depends on mechanisms enabling individuals to detect unreliability in their conspecifics. Yet, how such epistemic vigilance is achieved from naturalistic sensory inputs remains unclear. Here we show that listeners' perceptions of the certainty and honesty of other speakers from their speech are based on a common prosodic signature. Using a data-driven method, we separately decode the prosodic features driving listeners' perceptions of a speaker's certainty and honesty across pitch, duration and loudness. We find that these two kinds of judgments rely on a common prosodic signature that is perceived independently from individuals' conceptual knowledge and native language. Finally, we show that listeners extract this prosodic signature automatically, and that this impacts the way they memorize spoken words. These findings shed light on a unique auditory adaptation that enables human listeners to quickly detect and react to unreliability during linguistic interactions.

Linking human male vocal parameters to perceptions, body morphology, strength and hormonal profiles in contexts of sexual selection

Sexual selection appears to have shaped the acoustic signals of diverse species, including humans. Deep, resonant vocalizations in particular may function in attracting mates and/or intimidating same-sex competitors. Evidence for these adaptive functions in human males derives predominantly from perception studies in which vocal acoustic parameters were manipulated using specialist software. This approach affords tight experimental control but provides little ecological validity, especially when the target acoustic parameters vary naturally with other parameters. Furthermore, such experimental studies provide no information about what acoustic variables indicate about the speaker-that is, why attention to vocal cues may be favored in intrasexual and intersexual contexts. Using voice recordings with high ecological validity from 160 male speakers and biomarkers of condition, including baseline cortisol and testosterone levels, body morphology and strength, we tested a series of pre-registered hypotheses relating to both perceptions and underlying condition of the speaker. We found negative curvilinear and negative linear relationships between male fundamental frequency (fo) and female perceptions of attractiveness and male perceptions of dominance. In addition, cortisol and testosterone negatively interacted in predicting fo, and strength and measures of body size negatively predicted formant frequencies (Pf). Meta-analyses of the present results and those from two previous samples confirmed that fonegatively predicted testosterone only among men with lower cortisol levels. This research offers empirical evidence of possible evolutionary functions for attention to men's vocal characteristics in contexts of sexual selection.

Voice Pitch – A Valid Indicator of One’s Unfaithfulness in Committed Relationships?

Objectives

When judging a male speakers’ likelihood to act sexually unfaithful in a committed relationship, listeners rely on the speakers’ voice pitch such that lower voice pitch is perceived as indicating being more unfaithful. In line with this finding, a recent study (Schild et al. Behavioral Ecology, 2020) provided first evidence that voice pitch might indeed be a valid cue to sexual infidelity in men. In this study, male speakers with lower voice pitch, as indicated by lower mean fundamental frequency (mean F0), were actually more likely to report having been sexually unfaithful in the past. Although these results fit the literature on vocal perceptions in contexts of sexual selection, the study was, as stated by the authors, underpowered. Further, the study solely focused on male speakers, which leaves it open whether these findings are also transferable to female speakers.

Methods

We reanalyzed three datasets (Asendorpf et al. European Journal of Personality, 25, 16–30, 2011; Penke and Asendorpf Journal of Personality and Social Psychology, 95, 1113–1135, 2008; Stern et al. 2020) that include voice recordings and infidelity data of overall 865 individuals (63,36% female) in order to test the replicability of and further extend past research.

Results

A significant negative link between mean F0 and self-reported infidelity was found in only one out of two datasets for men and only one out of three datasets for women. Two meta-analyses (accounting for the sample sizes and including data of Schild et al. 2020), however, suggest that lower mean F0 might be a valid indicator of higher probability of self-reported infidelity in both men and women.

Conclusions

In line with prior research, higher masculinity, as indicated by lower mean F0, seems to be linked to self-reported infidelity in both men and women. However, given methodological shortcomings, future studies should set out to further delve into these findings.

No evidence for an association between facial fluctuating asymmetry and vocal attractiveness in men or women

Facial fluctuating asymmetry (FA), presumably a proxy measure of developmental instability, has been proposed to inversely relate to vocal attractiveness, which may convey information on heritable fitness benefits. Using an improved method of measuring facial FA, we sought to replicate two recent studies that showed an inverse correlation of facial FA with vocal attractiveness. In two samples of men (N = 165) and women (N = 157), we investigated the association of automatically measured facial FA based on 3D face scans with male and female observer-rated attractiveness of voice recordings. No significant associations were found for men or women, also when controlling for facial attractiveness, age, and body mass index. Equivalence tests show that effect sizes were significantly smaller than previous meta-analytic effects, providing robust evidence against a link of facial FA with vocal attractiveness. Thus, our study contradicts earlier findings that vocal attractiveness may signal genetic quality in humans via an association with FA.

How does familiarity with a voice affect trait judgements?

From only a single spoken word, listeners can form a wealth of first impressions of a person's character traits and personality based on their voice. However, due to the substantial within-person variability in voices, these trait judgements are likely to be highly stimulus-dependent for unfamiliar voices: The same person may sound very trustworthy in one recording but less trustworthy in another. How trait judgements differ when listeners are familiar with a voice is unclear: Are listeners who are familiar with the voices as susceptible to the effects of within-person variability? Does the semantic knowledge listeners have about a familiar person influence their judgements? In the current study, we tested the effect of familiarity on listeners' trait judgements from variable voices across 3 experiments. Using a between-subjects design, we contrasted trait judgements by listeners who were familiar with a set of voices - either through laboratory-based training or through watching a TV show - with listeners who were unfamiliar with the voices. We predicted that familiarity with the voices would reduce variability in trait judgements for variable voice recordings from the same identity (cf. Mileva, Kramer & Burton, Perception, 48, 471 and 2019, for faces). However, across the 3 studies and two types of measures to assess variability, we found no compelling evidence to suggest that trait impressions were systematically affected by familiarity.

Linking men's voice pitch to actual and perceived trustworthiness across domains

Previous research suggests that judgments about a male speaker's trustworthiness vary due to the speaker's voice pitch (mean F0) and differ across domains. However, mixed results in terms of the direction and extent of such effects have been reported. Moreover, no study so far has investigated whether men's mean F0 is, indeed, a valid cue to their self-reported and behavioral trustworthiness, and whether trustworthiness judgments are accurate. We tested the relation between mean F0 and actual general, economic, and mating-related trustworthiness in 181 men, as well as trustworthiness judgments of 95 perceivers across all three domains. Analyses show that men's mean F0 is not related to Honesty–Humility (as a trait indicator of general trustworthiness), trustworthy intentions, or trust game behavior, suggesting no relation of mean F0 to general or economic trustworthiness. In contrast, results suggest that mean F0 might be related to mating-related trustworthiness (as indicated by self-reported relationship infidelity). However, lower mean F0 was judged as more trustworthy in economic but less trustworthy in mating-related domains and rather weakly related to judgments of general trustworthiness. Trustworthiness judgments were not accurate for general or economic trustworthiness, but exploratory analyses suggest that women might be able to accurately judge men's relationship infidelity based on their voice pitch. Next to these analyses, we report exploratory analyses involving and controlling for additional voice parameters.