==== Front
Sci Rep
Sci Rep
Scientific Reports
2045-2322
Nature Publishing Group UK London

33277544
77940
10.1038/s41598-020-77940-z
Article
Linking human male vocal parameters to perceptions, body morphology, strength and hormonal profiles in contexts of sexual selection
Schild Christoph 1
Aung Toe 2
Kordsmeyer Tobias L. 3
Cardenas Rodrigo A. 4
Puts David A. dap27@psu.edu

2
Penke Lars lpenke@uni-goettingen.de

3
1 Department of Psychology, University of Copenhagen, Øster Farimagsgade 2A, 1353 Copenhagen, Denmark
2 Department of Anthropology and Center for Brain, Behavior and Cognition, Pennsylvania State University, University Park, PA 16802 USA
3 Department of Psychology and Leibniz ScienceCampus Primate Cognition, University of Goettingen, Gosslerstrasse 14, 37073 Göttingen, Germany
4 Department of Psychology, Pennsylvania State University, University Park, PA 16802 USA
4 12 2020
4 12 2020
2020
10 2129621 2 2020
18 11 2020
© The Author(s) 2020, corrected publication 2021
https://creativecommons.org/licenses/by/4.0/ Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
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.

Subject terms

Evolution
Evolutionary theory
Sexual selection
Human behaviour
Projekt DEALOpen Access funding enabled and organized by Projekt DEAL.

issue-copyright-statement© The Author(s) 2020
==== Body
Introduction

Acoustic signals comprise a fundamental component of mating competition1–4 and are highly sexually dimorphic in many species, including many anthropoid primates. Humans in particular exhibit strong sexual dimorphism in acoustic signals5, such that the distributions of male and female vocal parameters related to pitch and timbre barely overlap6.

From hearing the voice alone, humans can assess diverse salient social characteristics of a speaker, such biological sex, age and physical strength7–9. Many of these evaluations rely on inter-individual variation in specific sets of vocal parameters, including fundamental frequency and formant frequencies5,10. Fundamental frequency (fo) is the rate of vocal fold vibration during phonation and influences perceptions of pitch. Formant frequencies are resonant frequencies determined by the length and shape of the vocal tract and influence perceptions of vocal timbre.

Fundamental and formant frequencies are some of the most sexually dimorphic characteristics in humans, suggesting a past influence of sexual selection11. Indeed, lower male fo predicts greater perceptions of attractiveness, dominance and masculinity12–14, as well as greater mating success14,15 (but see16 for a null finding) and reproductive success15,17 (see also18,19). Likewise, male formant frequencies influence perceptions of attractiveness, dominance and masculinity12,13,20,21.

Despite the abundance of evidence linking acoustic parameters to perceptions relevant in mating competition, a fundamental question remains: Why have humans evolved to attend to these parameters? Costly signaling theory (originally proposed by22,23, but see24) which concerns the transmission of reliable information between signalers and receivers, is a useful theoretical tool to answer this question and helps us understand the maintenance of signal honesty via receiver-independent (production costs, developmental costs, maintenance costs) and receiver-dependent costs (e.g., retaliation costs, vulnerability costs; see25,26 for reviews). Recently, some authors27,28 have pointed out weak receiver-independent costs associated with men’s fo and concluded that men’s fo does not signal formidability. Others29–31 suggest that men’s fo is likely to be partly honest.

Although fo influences perceptions of physical dominance, it correlates only weakly with physical strength6,9,32 (see29 for a meta-analysis) and body height33. Past research also points to associations with hormonal profiles in males: fo decreases strongly during, and higher circulating testosterone levels predict lower fo in men11,34,35 (see29 for a meta-analysis). Further, the relationship between fo and testosterone was found to be stronger in men with lower cortisol levels5, a pattern that has been associated with immunocompetence36. Another study37 that utilized salivary immunoglobulin-A (sIgA; a marker of mucosal immunity) as a measure of immunocompetence reported that sIgA was negatively correlated with fo. In a similar vein, listeners assigned higher dominance ratings, but not higher health ratings, to speakers with higher self-reported health38. Overall, these studies suggest, that fo may be a partly honest signal of condition29–31. Formants are closely tied to vocal tract length and are therefore indirect, albeit weak, correlates of body size in humans33,39,40. Additionally, a recent study showed significant correlations with other somatometric measures, such as body mass index and hip circumference41. However, links between formants and physical strength are equivocal6,32.

In addition to the paucity of evidence concerning the information content of male voices, there are also significant gaps in knowledge concerning how men’s voices may influence social perceptions. For example, because most prior studies manipulated only one acoustic parameter at a time in experimental settings, the relative importance of different parameters in forming social judgments have not been well characterized. Prior research also has primarily investigated linear relationships (Table 1), and thus it remains largely unknown whether acoustic parameters have curvilinear effects on perceptions, which have been predicted in some cases11. Vocal stimuli in most prior work are also unnaturally invariant in content and motivation, with all speakers uttering a series of vowels, counting, or speaking precisely the same, often socially irrelevant, phrase; hence, the generalizability and external validity of such results depend on whether the effects they reveal persist in natural speech13. Finally, only a few, mostly low-powered studies (Table 1) have simultaneously shown that these acoustic parameters are related to both perceptions of attractiveness and/or dominance on the one hand and indirect measures of mate quality and formidability on the other.Table 1 A non-exhaustive list of studies (n = 50) on human voice perception.

No	Studies	Rater (n)	Vocalizers (n)	Perceptions evaluated	Vocalizer's condition	Natural voices	Cuvilinear tested	
1	Schild et al.42	95	181	Trus	Trus	 + 	 + 	
2	Collins and Missing43	30	30	Att; Age	Size	 + 		
3	Puts et al.5	1126	548	Att; Dom	T; C	 + 		
4	Raine et al.44	150	61	Size	Size	 + 		
5	Raine et al.45	135	61	Size	Size	 + 		
6	Rendall et al.46	163	68	Size	Size	 + 		
7	Rosenfield et al.15	84	4	Att; Pres; Dom	MS	 + 		
8	Šebesta et al.47	62	93	Att	Size	 + 		
9	Šebesta et al.48	63	40	Dom	Size	 + 		
10	Simmons et al.49	30	44	Att; Mas	Semen	 + 		
11	Valentova et al.50	203	152	Att	Size	 + 		
12	Armstrong et al.27	224	183	Dom; Size	Size	 + 		
13	Feinberg et al.51	991	123	Age; Att; Fem		 + 	 + 	
14	Babel et al.52	30	60	Att		 + 		
15	Gregory et al.53	118	60	Com Qual		 + 		
16	Hodges-Simeon et al.13	330	111	Att; Dom		 + 		
17	Knowles et al.54	180	32	Cop		 + 		
18	Michalsky and Schoormann55	20	20	Att; Like		 + 		
19	Pisanski and Rendall56	129	89	Size; Att; Mas; Fem		 + 		
20	Pisanski et al.57	68	20	Size; Att; Mas; Fem		 + 		
21	Sorokowski et al.58	39	51	Comp; Auth		 + 		
22	Valentova et al.59	84	30	Att; Mas		 + 		
23	Hill et al.60	1349	471	Att	Fac Sym		 + 	
24	Wolff and Puts61	376	117	Dom	Size; T; Agg		 + 	
25	Shirazi et al.62	128	6	Att	E; P			
26	Re et al.63	19	64	Att; Mas; Fem			 + 	
27	Saxton et al.64	40	6	Att; Dom			 + 	
28	Apicella and Feinberg65	88	10	Att				
29	Borkowska and Pawlowski66	473	58	Att; Dom				
30	Bruckert et al.67	64	55	Att				
31	Feinberg et al.68	68	5	Att; Dom				
32	Feinberg et al.69	26	8	Att; Dom				
33	Feinberg et al.70	1759	6	Pref				
34	Feinberg et al.71	83	6	Att				
35	Fraccaro et al.72	179	8	Att; Dom				
36	Hughes et al.73	40	40	Att				
37	Jones et al.74	800	12	Att; Dom				
38	Klofstad et al.75	382	27	Com; Size; Trus				
39	Leaderbrand et al.76	48	4	Att				
40	O'Connor et al.77	138	6	Att; Inv				
41	Puts et al.78	86	111	Dom				
42	Puts et al.20	42	30	Dom				
43	Puts et al.79	109	4	Att; Flir				
44	Puts14	142	111	Att				
45	Riding et al.80	54	9	Att				
46	Suire et al.81	225	58	Att				
47	Tigue et al.82	165	15	Int; Prow; Vote				
48	Vukovic et al.83	70	6	Att; Dom; Trus				
49	Watkins et al.84	50	10	Dom				
50	Xu et al.85	42	2	Att; Emo				
A list of 50 studies that relate to mating-relevant perceptions of human voice was obtained via Google Scholar search. Most studies that investigate human voice perceptions tested only on perceptions (n = 35), used manipulated voice stimuli (n = 28), and tested linear relationships (n = 44). Agg = Aggressiveness; Att = Attractiveness; C = Cortisol; Com = Competent; Com Qual = Communication Quality; Cop = Cooperativeness; Dom = Dominance; Emo = Emotions; E = Estradiol; Fac Sym = Facial Symmetry; Flir = Flirtatiousness; Fem = Femininity; Int = Integrity; Inv = Investing; Mas = Masculinity; MS = Mating Success; P = Progesterone; Pref = Preference; Pres = Prestige; Prow = Prowess; T = Testosterone; Trus = Trustworthiness; +  = Presence.

Given the fundamental gaps in knowledge outlined above, we conducted a preregistered study (preregistration: https://osf.io/nrmpf/) to examine (1) how vocal parameters are utilized in assessing dominance and attractiveness, and (2) why using those parameters for judgments could be adaptive insofar as they are associated with indirect measures of mate quality and/or formidability. In contrast to most studies on perceived vocal attractiveness and dominance, which have used standardized voice samples (i.e. counting, vowels or standardized passages), more natural stimuli were used to augment external validity. Importantly, we use a relatively large (N = 160) and rich dataset, which allows relationships between vocal parameters, baseline cortisol and testosterone levels, body morphology and strength to be tested in a single sample.

Perceptions of attractiveness and dominance

Because deep male voices may display social power29, threat potential11, and predict greater anticipated42,86,87 and actual42,88 sexual infidelity, there may be costs as well as benefits to mating with males with masculine voices11. Further, some studies suggest that the link between mean fo and attractiveness is weaker and rather curvilinear: Very low-pitched voices are not seen as more attractive and sometimes even less attractive as low-pitched voices11,64. In line with the context-dependent nature of costs and benefits and reports from previous literature, we therefore predicted negative linear5 and negative quadratic11 relationships between attractiveness ratings and both mean fo (H1) and formant position (Pf) (H2). Pf is a measure of formant structure, calculated as the average standardized formant value for the first n (usually four) formants6.

Masculine voices (i.e. low fo and Pf) have been found to be preferred by females to a greater extent in short-term compared to long-term relationship contexts14,89. This might reflect an adaptive trade-off strategy in which a mate’s genetic fitness, putatively indicated by masculine traits, is granted greater value in short-term contexts, whereas his expected investment and fidelity are valued more in long-term contexts89,90. Consequently, we predicted stronger relationships between short-term, compared to long-term, attractiveness ratings and both mean fo (H3) and Pf (H4).

It has been hypothesized that deep voices display threat potential6; hence, we predicted negative relationships between dominance ratings and both mean fo (H5) and Pf (H6). According to the source-filter theory, fo and Pf are theoretically distinct91. They are also only weakly correlated10 and seem to convey different information about a male speaker6. Accordingly, we predicted fo and Pf to be independent predictors of both attractiveness (H7) and dominance (H8) ratings.

Indirect measures of mate quality and formidability

Previous studies34,35 linked lower fo to higher circulating testosterone levels, and more recently this relationship was found to be stronger in men with lower cortisol levels5, a result seemingly consistent with the stress-linked immunocompetence handicap hypothesis that fo honestly signals a speaker’s physical condition36. We therefore predicted a negative relationship between mean fo and testosterone (H9) and predicted that this relationship would be attenuated by high baseline cortisol (H10).

Formants have been shown to relate moderately to body height, a phenotype that is relevant in both intra- and intersexual selective contexts92. We therefore predicted a negative relationship between Pf and body height (H11).

Exploratory analyses

In addition to these preregistered predictions, we conducted the following exploratory analyses. First, we examined how vocal parameters related to physical strength and body morphology. Second, we compared whether distinct parameters are used as cues for ratings on social dominance (i.e. being respected) and physical dominance (i.e. fighting ability), as they describe separate aspects of social evaluation93. Third, we explored whether jitter and shimmer influence attractiveness and dominance perceptions, as these acoustic parameters seem to provide information on male body shape. Jitter and shimmer quantify cycle-to-cycle variation in fo and amplitude, respectively, and influence perceptions of voice roughness. Fourth, we conducted three mediation analyses: (1) a moderated mediation model to test whether fo mediates the relationship between vocalizers’ testosterone levels (condition) and dominance ratings (perception), and whether this mediation is further moderated by cortisol, (2) a mediation model to test whether fo and Pf, mediate the relationship between vocalizers’ height and dominance ratings, and 3) a mediation model to test whether fo and Pf, mediate the relationship between vocalizers’ composite measure of size (extracted via factor analysis with varimax rotation) and dominance ratings. We conducted a separate mediation model for height, in addition to its inclusion in the factor analysis, as height has been shown to reflect good nutrition and low stress during development, as well as genetic predictors of immune function94. Additionally, a recent study31 reported that fo mediated the relationship between height and physical dominance ratings in two separate samples. Finally, we conducted three meta-analyses to test: (1) the mediating effect of fo between height and dominance ratings, (2) whether cortisol and testosterone negatively interact to predict male fo, and 3) whether fo negatively predicts testosterone levels, especially among men with lower cortisol levels.

Design and methods

Participants

One hundred sixty-five heterosexual males participated in a study on testosterone reactivity and personality state changes, which was conducted at the University of Goettingen, Germany (for details, see95). Each participant provided a standardized video recording, saliva samples, body morphology measurements, and handgrip as well as upper-body strength. Data from five individuals could not be used due to technical issues during video recording or because consent for further use of the video material was not given, resulting in a final sample of 160 males (mean age = 24.28, SD = 3.25 years). All participants were at least 18 years old. In a sensitivity power analysis using G*Power96 this sample had sufficient power (> 0.80) to detect an effect size of r =  + / − 0.20, assuming one-tailed alpha = 0.05. All procedures were in accordance with relevant guidelines and regulations, and received ethics approval from the local Ethics Committees at the University of Goettingen and the Pennsylvania State University. Informed consent was obtained from all subjects.

Voice recordings

Standardized video recordings were obtained using a Full-HD camera and Line6 Modell XD-V75 microphones. The participants were instructed to describe what is great about themselves, choosing three domains such as “friendship” or “success in studies/job” from a list of overall eight domains (for details, see95). The video clips were cut to a length of 5 s, beginning 5 s after participants had begun to speak, and voice clips were extracted. Five seconds were chosen because vocal parameters usually show strong correlations across different recordings, independent of length and content88,97, and both attractiveness and dominance ratings are stable and highly correlated across different recordings6,97. Further, the use of relatively brief voice clips allowed us to avoid rater fatigue. The voice clips were analyzed using PRAAT software98 (Version 6.0.36). The measures obtained were mean fo, the first four formant frequencies (F1–F4), four measures of jitter and five measures of shimmer. Because both jitter (all rs > 0.83, ps < 0.001) and shimmer measures (all rs > 0.56, ps < 0.001) were highly intercorrelated, a standardized mean was calculated for each perturbation measure10. Additionally, Pf was computed for the first four formants6. Formants were measured at each glottal pulse using automated detection in PRAAT. Formant measurement across standardized speech samples produces highly similar results to measurement of individual vowels and averaging across these measurements6.

It should be noted that different methods of measuring formant structure are used across studies. Formant dispersion (Df), for example, describes the distance between the highest (e.g., F4) and lowest formants (e.g., F1) measured39. While Df is commonly used, it has also been criticized especially for not using information about the middle formants (e.g., F2 and F3). Further, although Df is theoretically dependent on body height, other measures of formant structure have shown stronger relations with body height 6,33. One of these measures is formant position (Pf) which describes the average standardized formant value for the first n formants (e.g., F1–F4) and thus utilizes information of all formants measured6. Given these advantages of Pf over Df, Pf was chosen as the relevant measure for formant structure in this study. For further discussion, see 6.

Saliva samples

Based on previous studies99,100, we controlled for circadian variation in participants’ hormonal reactivity by collecting saliva samples only between 2 and 6 pm. Approximately 12–15 min after each participant arrived at the lab, he rinsed his mouth with water and provided at least 2 ml of saliva via passive drool through a straw, just prior to the video recording. The collected samples were immediately transported to an ultra-low temperature freezer (− 80 °C), where salivary testosterone is expected to be stable for at least 36 months101. At the end of the data collection period (see95 for details), saliva samples were shipped on dry ice to the Technical University of Dresden and analyzed using chemiluminescence-immuno-assays with high sensitivity (IBL International, Hamburg, Germany). The intra- and inter-assay coefficients (CVs) for cortisol are below 8% and for testosterone below 11%. Basal cortisol and testosterone outliers were identified and winsorized to 3 SDs102. To correct for skewness, we log10-transformed both variables.

Body morphology and strength measurements

As this procedure was also reported in103, procedural and methodological descriptions overlap. Participants were scanned three times using a Vitus Smart XXL 3D body scanner, running AnthroScan software (both Human Solutions GmbH, Kaiserslautern, Germany). Participants wore standardized tight underwear and were instructed to stand upright with legs hip-width apart, arms extended and held slightly away from the body, making a fist with thumbs showing forward, the head positioned in accordance with the Frankfort Horizontal, and to breathe normally during the scanning process. Using AnthroScan’s automatic measures (according to ISO 20685), we extracted muscularity-relevant body dimensions from the body scan: body volume, bust-chest girth, buttock girth, chest-to-hip ratio (CHR), forearm girth, lower limb (“leg”) length-to-height ratio (LHR), shoulder-to-hip ratio (SHR), thigh girth, upper arm girth, waist girth, waist-to-chest ratio (WCR), and waist-to-hip ratio (WHR). An aggregate indicator of upper body size was calculated by averaging z-standardized shoulder width, bust-chest girth, and upper arm girth104. Weight (in kg) was measured as part of the first body scanning process with the integrated SECA 635 scale (SECA, Hamburg, Germany). Body height (in cm) was measured twice using a stadiometer while participants stood barefoot, and the two values were averaged (ICC = 0.996). Body-mass index (BMI) was calculated from average weight and height measures (kg/cm2). Upper body and handgrip strength were measured using a hand dynamometer (Saehan SH5001). Each measurement was taken three times, starting with handgrip strength, for which participants were asked to use their dominant hand (88.2% used their right). As in105, upper body strength was measured by having participants hold the dynamometer in front of their chest with both hands and press both handles toward the middle as strongly as possible. A composite strength measure was formed by averaging the maximum values for each of the three measures of handgrip and upper body strength (ICCs: 0.81 and 0.64, respectively).

Attractiveness and dominance ratings

In exchange for course credit, 120 men (mean age = 19.82, SD = 2.71 years) and 120 women (mean age = 19.90, SD = 3.80 years) participated in a rating study on short- and long-term attractiveness as well as social and physical dominance at the Pennsylvania State University. All raters were at least 18 years old. Raters were equipped with Sennheiser HD 280 Professional Headphones and seated at private workstations. Raters provided demographic data on age, gender, sexual orientation, and relationship status. To control for the influence of semantic content, we also asked raters to indicate their German language comprehension (“How well do you understand German?”) on a 7-point Likert scale from 0 (“Not at All”) to 6 (“Fluent”). Below, we report results with all participants, but excluding raters score 2 or higher (n = 26) does not change results. Raters were then randomly assigned to one of four rating experiments, each asking for perceptions of either short-term attractiveness, long-term attractiveness, social dominance, or physical dominance of 160 randomly assigned voice files (for specific items see Appendix A). The voice file pool contained 320 voice samples that were taken from the 160 former targets before and after the competitive setting95. Raters always rated both files of a target, but both recordings of the same individual were separated by at least ten other voice samples. However, only ratings of the recordings before the competition were used in the present study. To ensure that each file was rated 15 times by each sex, a file was removed from the pool of remaining files to be rated once this criterion was met. The only exception was long-term attractiveness, where one male rater dropped out because of technical issues. Because correlations between male and female ratings were high (all rs > 0.70, ps < 0.001), and intraclass correlations within each rating condition were at least satisfactory (all ICCs > 0.76, ps < 0.001), mean scores were calculated.

Results

For tests of directed hypothesis one-tailed tests were used, and for exploratory tests two-tailed tests were used. Analyses were conducted using R106.

Perceptions of Attractiveness and Dominance

Attractiveness H1) Predictions on negative linear and negative quadratic relationships between attractiveness ratings and mean fo were supported. We found that fo negatively linearly predicted both short-term and long-term attractiveness. Furthermore, we found significant negatively quadratic (inverted U-shaped) relationships between fo and both short-term (Fig. 1a) and long-term attractiveness (Fig. 1b). Comparisons of linear and curvilinear models showed that the relationship between fo and short-term attractiveness was significantly better described by the curvilinear model (F2,157 = 4.38, p = 0.038), while there was no significant difference between models for long-term attractiveness (F2,157 = 3.76, p = 0.054).Figure 1 Relationships between male fundamental frequency (fo) and perceptions. We observed negative curvilinear relationships between fo and (a) short-term attractiveness and (b) long-term attractiveness, (c) a negative linear relationship with physical dominance ratings, and (d) a non-significant relationship with social dominance ratings. All panels were plotted using the “ggplot2” package107.

H2) Predictions of negative linear and negative quadratic relationships between attractiveness ratings and Pf were only partially supported. We found no significant linear relationships between Pf and either short-term or long-term attractiveness. While the non-linear relationship of Pf and short-term attractiveness was not significant (Fig. 2a), a significant negative quadratic relationship between Pf and long-term attractiveness emerged (Fig. 2b).Figure 2 Relationships between male formant position (Pf) and perceptions. We observed negative curvilinear relationships between Pf and (a) short-term attractiveness and (b) long-term attractiveness, (c) a negative linear relationship with physical dominance ratings, and (d) social dominance ratings. All panels were plotted using the “ggplot2” package107.

H3) The prediction of a stronger relationship between mean fo and short-term, compared to long-term attractiveness ratings was supported. Although both attractiveness ratings were highly correlated (r = 0.82, p < 0.001), the relationship between fo and short-term attractiveness was significantly stronger (z = − 2.06, p = 0.020) when comparing dependent correlation coefficients108.

H4) The prediction of a stronger relationship between Pf and short-term, compared to long-term attractiveness ratings was supported; the relationship between Pf and short-term attractiveness was significantly stronger (z = − 2.00, p = 0.023) when comparing dependent correlation coefficients.

Dominance H5) The prediction of a negative relationship between dominance ratings and mean fo was partially supported: fo negatively predicted physical dominance (Fig. 1c), but not social dominance ratings (Fig. 1d). H6) The prediction of a negative relationship between dominance ratings and Pf was supported. Pf negatively predicted perceptions of both physical (Fig. 2c) and social (Fig. 2d) dominance ratings.

Independent Predictors H7) The prediction that mean fo and Pf are independent predictors of attractiveness ratings was partially supported. When fo and Pf were included in a multiple regression (F2,157 = 16.78, p < 0.001, R2 = 0.17), fo negatively predicted short-term attractiveness (β = − 0.40, p < 0.001), but Pf did not (β = − 0.08, p = 0.132). Similarly, fo negatively predicted long-term attractiveness (β = − 0.32, p < 0.001) in a multiple regression (F2,157 = 8.94, p < 0.001, R2 = 0.09), but Pf did not (β = 0.01, p = 0.471). Because the curvilinear relationship between long-term attractiveness and Pf was significant, we investigated whether the linear term of fo and the quadratic term of Pf were independent predictors of long-term attractiveness. Indeed, adding the quadratic term of Pf explained significantly more variance in long-term attractiveness ratings (F2,157 = 3.15, p = 0.045), with both predictors remaining significant. H8) The prediction that mean fo and Pf are independent predictors of dominance ratings was partially supported. Multiple regressions with fo and Pf as predictors (F2,157 = 31.73, p < 0.001, R2 = 0.28) showed that both independently predicted physical dominance (β = − 0.35, p < 0.001 for fo; β = − 0.37, p < 0.001 for Pf). For social dominance (F2,157 = 5.12, p = 0.007, R2 = 0.05), Pf was a significant predictor (β = − 0.25, p < 0.001), but fo was not (β = 0.02, p = 0.391).

Indirect measures of mate quality and formidability

Testosterone, cortisol and fo Testosterone levels were not significantly related to fo (r = − 0.07, p = 0.18). However, cortisol and testosterone interacted in predicting fo (β = 0.16, p = 0.024) (Fig. 3a). While these results do not support H9) a negative relationship between mean fo and testosterone, they supported H10) a negative relationship between mean fo and testosterone, which is attenuated by high baseline cortisol.Figure 3 Negative interaction between testosterone and cortisol on male fundamental frequency (fo). (a) A combination of higher testosterone and lower cortisol levels predict lower male fo in this study. (b) A meta-analysis on the interaction effects across studies, using a random-effects model yielded a significant overall effect. Follow-up meta-analyses on simple slopes of (c) lower cortisol levels yielded a significant negative relationship between testosterone and fo, and (d) higher cortisol levels yielded null results. Panel b was plotted via the “rsm” package109, and meta-analyses were conducted via the “metaphor” package110.

Body Morphology and Pf A significant relationship between Pf and body height was found (r = − 0.13, p = 0.046), supporting H11).

Exploratory analyses

Strength and Pf Additional exploratory analyses showed significant negative relationships between Pf and strength (r = − 0.25, p = 0.002). Further, Pf was significantly correlated with multiple body morphology measures related to volume and mass (Table 2).Table 2 Means, standard deviations, and correlations of body morphology measures with Pf.

Variable	M	SD	r	95% CI	
BMI	23.98	3.83	− .23***	[− .37, − .08]	
Body volume	79.88	14.03	− .27***	[− .41, − .12]	
Bust-chest girth	101.67	8.81	− .29***	[− .43, − .14]	
Buttock girth	100.18	7.25	− .26***	[− .40, − .11]	
Forearm girth	27.00	1.93	− .28***	[− .42, − .13]	
Physical strength	48.40	7.99	− .25**	[− .39, − .09]	
Thigh girth	57.58	4.97	− .22**	[− .37, − .07]	
Upper body size	56.96	4.13	− .31***	[− .44, − .16]	
Upper arm girth	30.20	2.67	− .25**	[− .39, − .09]	
Waist girth	84.63	9.86	− .24**	[− .39, − .09]	
Weight	78.68	13.96	− .27***	[− .41, − .12]	
Chest-to-hip ratio (CHR)	1.02	0.05	− .13	[− .28, .02]	
Waist-to-chest ratio (WCR)	1.21	0.07	.03	[− .13, .18]	
Waist-to-hip ratio (WHR)	0.84	0.05	− .15	[− .30, .00]	
Leg length-to-height ratio (LHR)	0.40	0.01	.12	[− .03, .27]	
Shoulder-to-hip ratio (SHR)	0.39	0.02	.08	[− .08, .23]	
M and SD are used to represent mean and standard deviation. Values in square brackets indicate the confidence interval for each correlation. ** indicates p < .01; *** indicates p < .001.

Perturbation measures, vocal perception and target parameters Pearson correlations showed significant negative relationships between shimmer and both social (r = − 0.31, p < 0.001) and physical dominance (r = − 0.31, p < 0.001). No significant relationships were found between shimmer and short-term (r = − 0.14, p = 0.076) or long-term attractiveness (r = − 0.12, p = 0.122). Jitter showed no significant relationship to any of the four ratings (all rs <  + / − 0.11, ps > 0.16). Moreover, the only significant relationship between perturbation measures and any of the target parameters was a significant negative correlation between shimmer and baseline cortisol (r = − 0.21, p = 0.006). Multiple regressions with fo, Pf, jitter and shimmer as predictors and all ratings as outcomes can be found in Tables S1–S4.

Mediation models In this analysis (model 7)111, cortisol level was recoded into two categories (median split), and their interaction term was computed by multiplying testosterone levels with dichotomized cortisol category. In this model, we found that testosterone levels (β =  − 0.09; p = 0.321), cortisol category (β = 0.07; p = 0.367) and their interaction term (β = 0.135; p = 0.119) did not predict fo. Adjusting for Pf (β =  − 0.39; p < 0.001), testosterone (β = 0.15; p = 0.023) and fo (β =  − 0.34; p < 0.001) significantly predicted physical dominance ratings. The indirect effect of testosterone on dominance ratings via fo was not significant (β = 0.06; p = 0.344), and no significant indirect effect was observed among men with lower cortisol (β = 0.04; p = 0.227), or men with higher cortisol levels (β = 0.02; p = 0.832).

We ran two additional mediation models: (1) fo and Pf were entered as mediators between height and physical dominance ratings, (2) fo and Pf were entered as mediators between physical strength and dominance ratings. A composite measure of physical size was extracted from a factor analysis (Fig. 4d) on the following body morphology measures that significantly correlated with Pf (Table 2): height, weight, body volume, bust-chest girth, buttock girth, forearm girth, physical strength, thigh girth, upper body size, upper arm girth, and waist girth. In model 1, fo and Pf were entered as mediators between height and physical dominance ratings (Fig. 4a). Neither fo nor Pf was a significant mediator. In model 2, we found evidence that Pf mediated the relationship between physical strength condition and physical dominance ratings (Fig. 4b).Figure 4 Male fundamental frequency (fo) and formant position (Pf) as mediators of vocalizers’ condition and perceivers’ ratings. (a) Although height predicted physical dominance ratings, fo and Pf did not mediate this relationship. (b) Pf, but not fo, significantly mediated the relationship between composite size and physical dominance ratings. (c) Although fo was not found to be a significant mediator between height and physical dominance ratings in the present study, a meta-analysis using a random-effects model indicated a significant mediating effect, with fo mediating 44% of the relationship between height and physical dominance. Proportion mediated lower than 0 indicates the suppression effect of a mediating variable. In addition, the current study used mean dominance ratings as the primary unit of analyses for calculating proportion mediated, whereas Aung et al., Study 1 (n = 8,103 observations) and Study 2 (n = 6,586 observations) used individual ratings. (d) Using the “nFactors” package112 and rotated factors with Varimax method using the “psych” package113, we reduced the set of size related measures into one dimensional factor (n = 1), which we labelled “composite size”, via principal axis factoring analysis. ***p < .001.

Meta-analyses We combined results of the present study with prior results31 in a meta-analysis to assess the strength of the mediating effect of fo on the relationship between height and perceptions of physical dominance. We found a significant overall mediating effect of fo, independent of Pf (Fig. 4c); fo mediated about 44% the relationship between height and physical dominance ratings.

We also conducted a meta-analysis of the interaction of testosterone and cortisol in predicting fo. For this analysis, the t-value and degrees of freedom (df) of the overall interaction effect were transformed into a correlation114. The effect of the testosterone and cortisol interaction on male fo (k = 3, n = 279) was significant: r = 0.23, p = 0.001, 95% CI [0.12, 0.34] (Fig. 3b). In follow-up analyses, the relationship between testosterone and fo was significant in men with low cortisol levels (Fig. 3c), but not in those with high cortisol levels (Fig. 3d).

Finally, Fig. 5 provides a lens model115 overview of the key relations between perceptions, vocal cues and target parameters found in this study.Figure 5 Lens model overview of the study results. Connections indicate significant relations (p < .05).

Discussion

We investigated the role of vocal parameters in perceptions of male attractiveness and found that fo was the strongest predictor of short- and long-term attractiveness among the vocal parameters measured (Pf, shimmer, and jitter). Consistent with previous studies11,64, the relationship between fo and male vocal attractiveness was both negatively linear and negatively curvilinear, the latter suggesting that women’s voice preferences may reflect a tradeoff between the potential genetic or other benefits versus the potential costs of mating with masculine males6. Such costs may include lower investment and perhaps risk of interpersonal violence. Low male fo has previously been linked to sexual infidelity42,88,89,116, and several lines of evidence suggest that phenotypic masculinity—and vocal masculinity in particular—indicate threat potential not only to same-sex competitors but also to potential mates. For example, images of male-on-female violence disrupted U.S. women’s preferences for both masculine voices and faces117, and Colombian women with perceptions of greater local domestic violence preferred less masculine male faces118. In another study, Filipino women who were younger and rated themselves as less attractive tended to prefer feminized male fo, again suggesting that women’s fo preferences may in part reflect their own perceived vulnerability62. In our data, fo was a stronger predictor of short-term than long-term attractiveness, once again supporting the notion of a mate choice trade-off in which putative indicators of genetic fitness are prioritized in short-term contexts, and expected investment and fidelity are prioritized in long-term contexts90.

Although Pf predicted strength and body morphology in our study and predicted ratings of attractiveness in some prior studies13,21, it did not predict attractiveness in another large sample5 and was unrelated to short-term attractiveness and only weakly negatively curvilinearly linked to long-term attractiveness in the present study. These lines of evidence suggest that the information provided by formant frequencies may be less relevant to mate quality than that provided by fo. By contrast, shimmer negatively predicted both short- and long-term attractiveness ratings. Shimmer is utilized to assess vocal quality in clinical contexts, such that pathological voices show higher shimmer levels than those of healthy individuals119–121; however, a composite of shimmer and harmonics-to-noise ratio (which were highly correlated) showed no relationship to dominance or attractiveness perception in a recent study5. These divergent findings may be explained by the fact that the latter study used voice samples in which male individuals read a standardized voice passage, while our study used more natural but less standardized stimuli that might have been influenced more strongly by the speaker’s affective state.

Importantly, a Fisherian mate choice model via runaway sexual selection has also been suggested as a possible driver favoring low male fo14,122. A Fisherian model would suggest that female choice primarily drives and exaggerates the evolution of male traits; hence, the model predicts that females prefer males with the lowest fo. However, evidence from the current study and previous studies15,62,65 (suggests a general preference for lower fo by women, but also a relatively stronger negative linear relationship between fo and dominance perceptions by men across studies29.

While fo predicted both short- and long-term attractiveness, it predicted physical dominance but not social dominance, in line with previous studies13,123. Pf and shimmer were linked to both social and physical dominance ratings. A possible explanation for this pattern of results is that social dominance is influenced less by threat potential and more by other qualities, such as competence, communication and cooperation skills, or leadership qualities. These attributes might be more strongly associated with Pf and shimmer than with fo.

The other aim of this study was to explore whether attention to vocal cues is adaptive by investigating the information content of acoustic parameters. We replicated a negative relationship between Pf and height33 and found that Pf negatively predicted strength and several body morphology measures. Men with lower Pf were taller, stronger, and had larger bodies in general. Further, our mediation analysis indicated that Pf, independently of fo, mediated the relationship between a composite measure of body size and physical dominance ratings.

Importantly, baseline cortisol and testosterone levels interacted in predicting fo, such that testosterone levels more strongly negatively predicted fo as cortisol levels decreased across participants. When we entered the interaction term between testosterone and median-split cortisol levels into our exploratory moderated mediation analyses, the interaction effect became non-significant, likely due to reduced statistical power124 from dichotomizing a continuous variable (cortisol). Nevertheless, the overall interaction between testosterone and cortisol in predicting male fo was confirmed in a meta-analysis (Fig. 3b). Male fo was negatively correlated with testosterone when cortisol was low, whereas no significant relationship was observed between male fo and testosterone when cortisol was high (Fig. 3c). These patterns of relationships may help clarify why dose-dependent effects of androgen levels on the intensity of elaborate male traits are sometimes undetected125, and why fo is only weakly correlated with testosterone when cortisol is not considered. Across a variety of species, testosterone and cortisol are linked to measures of physical condition, including disease, stress, and diet126. The interaction between testosterone and cortisol, in particular, has been tied to immune function in birds127, but the functional and behavioral correlates of this hormonal interaction in humans are not yet clear36,128, and most studies are arguably underpowered. Further, a recent meta-analysis found only modest support for an interactive relationship between testosterone and cortisol in predicting status-relevant behavior (e.g., dominance & risk taking) and suggested that this association could be driven by publication bias and flexibility in data analysis129,130. Although only one paper5 besides the current one has reported the specific interaction effect of testosterone and cortisol on male fo, the meta-analysis reported here suggests that the interaction is robust.

There is widespread agreement5,11,27,40,46 that low male fo evolved to exaggerate apparent size by leveraging a predisposition to perceive low frequencies as emanating from large sound sources. Phylogenetic reconstruction suggests that relatively male fo evolved in the common ancestor of the catarrhine primates after their divergence from platyrrhines approximately 43.5mya5. Given the weak correspondence between fo and body size, some have argued that fo is purely deceptive and is not an honest indicator of physical dominance27,28,131. Others have suggested that fo may reliably correlate with other salient speaker characteristics such as status, threat, and dominance, and that these dimensions may overlap with, and hence intrude onto impressions of, size46. Our results better comport with the latter possibility. Indeed, relatively low male fo tends to be lost in primate species in which male-male mating competition is reduced, suggesting that there are costs associated with low fo that cause this trait to be selected against when compensatory benefits are absent.

Deference to males with low fo is demonstrably costly in humans in terms of social status, mates, and reproduction, and thus attention to fo would seemingly be selected against if fo did not provide valid information about male condition30. However, this does not mean that fo is cheat-proof, or that the assessment of condition or formidability from fo is largely accurate. Honest signals are often corrupted into conventional signals where cheating is common because the assessment of the signal itself is costly to the receiver132. Although we did not find support for the cortisol-moderated mediation role of fo between testosterone levels and physical dominance ratings in the present sample, this may be explained by reduced statistical power due to dichotomized cortisol levels and reduced sample sizes for testing two separate indirect effects. Indeed, we found a strong meta-analytic support for an overall interaction between testosterone and cortisol in predicting male fo, suggesting that fo conveys underlying endocrine state, if imprecisely, and lower male fo has consistently been shown to predict perceptions of physical dominance across multiple studies. Likewise, a recent study31 reported that fo mediated the relationship between developmental condition (measured via height) and physical dominance ratings in two separate samples with different types of vocal stimuli. Although we did not find that fo significantly mediated the relationship between height and physical dominance ratings in our data, our meta-analysis suggests that fo mediates about 44% of the relationship between height and physical dominance ratings. Collectively, our findings support the hypothesis that, while the correlation between fo and underlying quality is imperfect, fo might be utilized as one of many cues for assessing competitors and potential mates29 because it communicates the quality of the signaler significantly better than chance132,133.

Shimmer also negatively predicted social and physical dominance ratings, as well as lower cortisol levels. The latter finding is consistent with prior evidence that shimmer is reduced when stress is induced experimentally or when the speaker is under high tension134. However, the other perturbation measure, jitter, showed no such associations. Future research should continue to explore the relevance of jitter and shimmer to human sexual selection (see also), as they have been shown to be associated with pathological voice quality120 and body shape in men41 and might therefore be relevant in contexts of sexual selection.

One limitation with our study is that we tested only hypotheses associated with receiver-independent costs and did not consider receiver-dependent costs associated with attention to male fo. Some135,136 have suggested that additional mechanisms that incorporate receiver-dependent costs are required to ensure signal honesty. For example, under a mating-motive priming condition, male voices with low fo enhanced recognition for men with high threat potential135 and elicited aggressive cognitions and intent in men who perceived themselves to be more dominant and stronger136. Future studies should investigate the extent to which receiver-dependent and independent costs are needed in ensuring the signal honesty of low fo in cross-cultural contexts.

Following suggestions by Lakens137, we used one-sided significance tests for preregistered directional hypotheses. The only result influenced by this decision is the relation between Pf and height, which would be non-significant using a two-sided test. However, we note that meta-analytic findings33 suggest a robust link between Pf and height, and the lack of a significant relation in this particular study is likely due to a lack of statistical power. Thus, also our conclusions remain highly similar when two-sided tests are used.

Conclusion

Vocal parameters were linked to hormone levels, as well as body morphology and physical strength, and appear to be used for judgements relevant to intrasexual competition and intersexual mate choice. The present study thus provides evidence that natural interindividual variation in men’s vocal parameters influences judgements of attractiveness and dominance because these parameters provide valid information about speakers’ underlying condition.

Supplementary information

Supplementary information.

Appendix A

Supplementary information

is available for this paper at 10.1038/s41598-020-77940-z.

Author contributions

C.S., L.P., and D.A.P. conceived of the presented idea. C.S., L.P., and D.A.P. designed and planned the experiments. C.S., T.L.K., and D.A.P. planned the data collection and collected the data. R.A.C. programmed the rating study. C.S. and T.A. analyzed the data. C.S. took the lead in writing the manuscript. All authors provided critical feedback and helped shape the research, analysis, and manuscript.

Funding

Open Access funding enabled and organized by Projekt DEAL.

Competing interests

The authors declare no competing interests.

The original online version of this Article was revised: The original version of this Article contained an error in Figure 3, where the p value for the z-test was incorrect in panel (d).

Publisher's note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

These authors jointly supervised this work: David A. Puts and Lars Penke.

Change history

5/3/2021

A Correction to this paper has been published: 10.1038/s41598-021-89157-9
==== Refs
References

1. Cade WH Cade ES Male mating success, calling and searching behaviour at high and low densities in the field cricket Gryllus integer Anim. Behav. 1992 43 49 56
2. Fischer J Kitchen DM Seyfarth RM Cheney DL Baboon loud calls advertise male quality: acoustic features and their relation to rank, age, and exhaustion Behav. Ecol. Sociobiol. 2004 56 140 148
3. Mathevon N Koralek A Weldele M Glickman SE Theunissen FE What the hyena’s laugh tells: Sex, age, dominance and individual signature in the giggling call of Crocuta crocuta BMC Ecol. 2010 10 9 20353550
4. Mitani JC Sexual selection and adult male orangutan long calls Anim. Behav. 1985 33 272 283
5. Puts DA Sexual selection on male vocal fundamental frequency in humans and other anthropoids Proc. R. Soc. B 2016 283 20152830
6. Puts DA Apicella CL Cárdenas RA Masculine voices signal men’s threat potential in forager and industrial societies Proc. R. Soc. B Biol. Sci. 2012 279 601 609
7. Ptacek PH Sander EK Age recognition from voice J. Speech Hear. Res. 1966 9 273 277 5925532
8. Rezlescu C Dominant voices and attractive faces: the contribution of visual and auditory information to integrated person impressions J. Nonverbal Behav. 2015 39 355 370
9. Sell A Adaptations in humans for assessing physical strength from the voice Proc. R. Soc. B Biol. Sci. 2010 277 3509 3518
10. Jünger J Do women’s preferences for masculine voices shift across the ovulatory cycle? Horm. Behav. 2018 106 122 134 30342884
11. Puts DA Jones BC DeBruine LM Sexual selection on human faces and voices J. Sex Res. 2012 49 227 243 22380590
12. Cartei V Bond R Reby D What makes a voice masculine: physiological and acoustical correlates of women’s ratings of men’s vocal masculinity Horm. Behav. 2014 66 569 576 25169905
13. Hodges-Simeon CR Gaulin SJC Puts DA Different vocal parameters predict perceptions of dominance and attractiveness Hum. Nat. 2010 21 406 427 21212816
14. Puts DA Mating context and menstrual phase affect women’s preferences for male voice pitch Evol. Hum. Behav. 2005 26 388 397
15. Rosenfield KA Sorokowska A Sorokowski P Puts DA Sexual selection for low male voice pitch among Amazonian forager-horticulturists Evol. Hum. Behav. 2019 41 3 11
16. Kordsmeyer TL Hunt J Puts DA Ostner J Penke L The relative importance of intra- and intersexual selection on human male sexually dimorphic traits Evol. Hum. Behav. 2018 39 424 436
17. Apicella CL Feinberg DR Marlowe FW Voice pitch predicts reproductive success in male hunter-gatherers Biol. Lett. 2007 3 682 684 17895219
18. Smith KM Olkhov YM Puts DA Apicella CL Hadza men with lower voice pitch have a better hunting reputation Evol. Psychol. 2017 15 1474704917740466 29179581
19. Atkinson J Voice and handgrip strength predict reproductive success in a group of indigenous African females PLoS ONE 2012 7 e41811 22870251
20. Puts DA Hodges CR Cárdenas RA Gaulin SJC Men’s voices as dominance signals: vocal fundamental and formant frequencies influence dominance attributions among men Evol. Hum. Behav. 2007 28 340 344
21. Hodges-Simeon CR Gaulin SJC Puts DA Voice correlates of mating success in men: examining “contests” versus “mate choice” modes of sexual selection Arch. Sex. Behav. 2011 40 551 557 20369377
22. Zahavi A Mate selection—a selection for a handicap J. Theor. Biol. 1975 53 205 214 1195756
23. Grafen A Biological signals as handicaps J. Theor. Biol. 1990 144 517 546 2402153
24. Higham JP How does honest costly signaling work? Behav. Ecol. 2014 25 8 11
25. Penn DJ Számadó S The handicap principle: how an erroneous hypothesis became a scientific principle Biol. Rev. 2020 95 267 290
26. Reid, S. A., Zhang, J., Anderson, G. L. & Keblusek, L. Costly signaling in human communication. in The Handbook of Communication Science and Biology (eds. Floyd, K. & Weber, R.) 50–62 (Routledge, 2020).
27. Armstrong MM Lee AJ Feinberg DR A house of cards: bias in perception of body size mediates the relationship between voice pitch and perceptions of dominance Anim. Behav. 2019 147 43 51
28. Feinberg DR Jones BC Armstrong MM No evidence that men’s voice pitch signals formidability Trends Ecol. Evol. 2019 34 190 192 30655014
29. Aung T Puts D Voice pitch: a window into the communication of social power Curr. Opin. Psychol. 2019 33 154 161 31445439
30. Puts DA Aung T Does men’s voice pitch signal formidability? A reply to feinberg Trends Ecol. Evol. 2019 34 189 190 30594323
31. Aung, T., Rosenfield, K. A. & Puts, D. Male voice pitch mediates the relationship between objective and perceived formidability. Evol. Hum. Behav. (2020).
32. Han, C. et al. No clear evidence for correlations between handgrip strength and sexually dimorphic acoustic properties of voices. Am. J. Hum. Biol. 0, e23178.
33. Pisanski K Vocal indicators of body size in men and women: a meta-analysis Anim. Behav. 2014 95 89 99
34. Dabbs JM Mallinger A High testosterone levels predict low voice pitchamong men Personal. Individ. Differ. 1999 27 801 804
35. Evans S Neave N Wakelin D Hamilton C The relationship between testosterone and vocal frequencies in human males Physiol. Behav. 2008 93 783 788 18155094
36. Rantala MJ Evidence for the stress-linked immunocompetence handicap hypothesis in humans Nat. Commun. 2012 3 694 22353724
37. Arnocky S Hodges-Simeon CR Ouellette D Albert G Do men with more masculine voices have better immunocompetence? Evol. Hum. Behav. 2018 39 602 610
38. Albert, G., Arnocky, S., Puts, D. A. & Hodges-Simeon, C. R. Can listeners assess men’s self-reported health from their voice? Evol. Hum. Behav. (2020).
39. Fitch WT Vocal tract length and formant frequency dispersion correlate with body size in rhesus macaques J. Acoust. Soc. Am. 1997 102 1213 1222 9265764
40. Fitch WT The evolution of speech: a comparative review Trends Cogn. Sci. 2000 4 258 267 10859570
41. Pisanski K Voice parameters predict sex-specific body morphology in men and women Anim. Behav. 2016 112 13 22
42. Schild C Stern J Zettler I Linking men’s voice pitch to actual and perceived trustworthiness across domains Behav. Ecol. 2019 31 164 175
43. Collins SA Missing C Vocal and visual attractiveness are related in women Anim. Behav. 2003 65 997 1004
44. Raine J Pisanski K Bond R Simner J Reby D Human roars communicate upper-body strength more effectively than do screams or aggressive and distressed speech PLoS ONE 2019 14 e0213034 30830931
45. Raine J Pisanski K Oleszkiewicz A Simner J Reby D Human listeners can accurately judge strength and height relative to self from aggressive roars and speech iScience 2018 4 273 280 30240746
46. Rendall D Vokey JR Nemeth C Lifting the curtain on the Wizard of Oz: biased voice-based impressions of speaker size J. Exp. Psychol. Hum. Percept. Perform. 2007 33 1208 1219 17924818
47. Šebesta P Voices of Africa: acoustic predictors of human male vocal attractiveness Anim. Behav. 2017 127 205 211
48. Šebesta P Třebický V Fialová J Havlíček J Roar of a champion: loudness and voice pitch predict perceived fighting ability but not success in mma fighters Front. Psychol. 2019 10 859 31114519
49. Simmons LW Peters M Rhodes G Low pitched voices are perceived as masculine and attractive but do they predict semen quality in men? PLoS ONE 2011 6 e29271 22216228
50. Valentova JV Vocal parameters of speech and singing covary and are related to vocal attractiveness, body measures, and sociosexuality: a cross-cultural study Front. Psychol. 2019 10 2029 31695631
51. Feinberg DR DeBruine LM Jones BC Perrett DI The role of femininity and averageness of voice pitch in aesthetic judgments of women’s voices Perception 2008 37 615 623 18546667
52. Babel M McGuire G King J Towards a more nuanced view of vocal attractiveness PLoS ONE 2014 9 e88616 24586358
53. Gregory SW Dagan K Webster S Evaluating the relation of vocal accommodation in conversation partners’ fundamental frequencies to perceptions of communication quality J. Nonverbal Behav. 1997 21 23 43
54. Knowles KK Little AC Vocal fundamental and formant frequencies affect perceptions of speaker cooperativeness Q. J. Exp. Psychol. 2016 69 1657 1675
55. Michalsky, J. & Schoormann, H. Pitch convergence as an effect of perceived attractiveness and likability. in Interspeech 2017 2253–2256 (ISCA, 2017).
56. Pisanski K Rendall D The prioritization of voice fundamental frequency or formants in listeners’ assessments of speaker size, masculinity, and attractiveness J. Acoust. Soc. Am. 2011 129 2201 2212 21476675
57. Pisanski K Mishra S Rendall D The evolved psychology of voice: evaluating interrelationships in listeners’ assessments of the size, masculinity, and attractiveness of unseen speakers Evol. Hum. Behav. 2012 33 509 519
58. Sorokowski P Voice of authority: professionals lower their vocal frequencies when giving expert advice J. Nonverbal Behav. 2019 43 257 269
59. Valentová J Roberts SC Havlíček J Preferences for facial and vocal masculinity in homosexual men: the role of relationship status, sexual restrictiveness, and self-perceived masculinity Perception 2013 42 187 197 23700957
60. Hill AK Are there vocal cues to human developmental stability? Relationships between facial fluctuating asymmetry and voice attractiveness Evol. Hum. Behav. 2017 38 249 258
61. Wolff SE Puts DA Vocal masculinity is a robust dominance signal in men Behav. Ecol. Sociobiol. 2010 64 1673 1683
62. Shirazi TN Puts DA Escasa-Dorne MJ Filipino women’s preferences for male voice pitch: intra-individual, life history, and hormonal predictors Adapt. Hum. Behav. Physiol. 2018 4 188 206
63. Re DE O’Connor JJM Bennett PJ Feinberg DR Preferences for very low and very high voice pitch in humans PLoS ONE 2012 7 e32719 22403701
64. Saxton TK Mackey LL McCarty K Neave N A lover or a fighter? Opposing sexual selection pressures on men’s vocal pitch and facial hair Behav. Ecol. 2016 27 512 519 27004013
65. Apicella CL Feinberg DR Voice pitch alters mate-choice-relevant perception in hunter–gatherers Proc. R. Soc. B Biol. Sci. 2009 276 1077 1082
66. Borkowska B Pawlowski B Female voice frequency in the context of dominance and attractiveness perception Anim. Behav. 2011 82 55 59
67. Bruckert L Vocal attractiveness increases by averaging Curr. Biol. 2010 20 116 120 20129047
68. Feinberg DR Jones BC Little AC Burt DM Perrett DI Manipulations of fundamental and formant frequencies influence the attractiveness of human male voices Anim. Behav. 2005 69 561 568
69. Feinberg DR Menstrual cycle, trait estrogen level, and masculinity preferences in the human voice Horm. Behav. 2006 49 215 222 16055126
70. Feinberg DR DeBruine LM Jones BC Little AC Correlated preferences for men’s facial and vocal masculinity Evol. Hum. Behav. 2008 29 233 241
71. Feinberg DR Integrating fundamental and formant frequencies in women’s preferences for men’s voices Behav. Ecol. 2011 22 1320 1325
72. Fraccaro PJ Faking it: deliberately altered voice pitch and vocal attractiveness Anim. Behav. 2013 85 127 136
73. Hughes SM Mogilski JK Harrison MA The perception and parameters of intentional voice manipulation J. Nonverbal Behav. 2014 38 107 127
74. Jones BC Feinberg DR DeBruine LM Little AC Vukovic J A domain-specific opposite-sex bias in human preferences for manipulated voice pitch Anim. Behav. 2010 79 57 62
75. Klofstad Casey A Anderson Rindy C Peters S Sounds like a winner: voice pitch influences perception of leadership capacity in both men and women Proc. R. Soc. B Biol. Sci. 2012 279 2698 2704
76. Leaderbrand, K., Dekam, J., Morey, A. & Tuma, L. The effects of voice pitch on perceptions of attractiveness: do you sound hot or not. Winona State Univ. Psychol. Stud. J. (2008).
77. O’Connor JJM Female preferences for male vocal and facial masculinity in videos Ethology 2012 118 321 330
78. Puts DA Gaulin SJC Verdolini K Dominance and the evolution of sexual dimorphism in human voice pitch Evol. Hum. Behav. 2006 27 283 296
79. Puts DA Barndt JL Welling LLM Dawood K Burriss RP Intrasexual competition among women: vocal femininity affects perceptions of attractiveness and flirtatiousness Personal. Individ. Differ. 2011 50 111 115
80. Riding D Lonsdale D Brown B The effects of average fundamental frequency and variance of fundamental frequency on male vocal attractiveness to women J. Nonverbal Behav. 2006 30 55 61
81. Suire A Raymond M Barkat-Defradas M Male vocal quality and its relation to females’ preferences Evol. Psychol. 2019 17 1474704919874675 31564128
82. Tigue CC Borak DJ O’Connor JJM Schandl C Feinberg DR Voice pitch influences voting behavior Evol. Hum. Behav. 2012 33 210 216
83. Vukovic J Variation in perceptions of physical dominance and trustworthiness predicts individual differences in the effect of relationship context on women’s preferences for masculine pitch in men’s voices Br. J. Psychol. 2011 102 37 48 21241284
84. Watkins CD Taller men are less sensitive to cues of dominance in other men Behav. Ecol. 2010 21 943 947
85. Xu Y Lee A Wu W-L Liu X Birkholz P Human vocal attractiveness as signaled by body size projection PLoS ONE 2013 8 e62397 23638065
86. O’Connor JJM Re DE Feinberg DR Voice pitch influences perceptions of sexual infidelity Evol. Psychol. 2011 9 147470491100900100
87. O’Connor JJM Barclay P The influence of voice pitch on perceptions of trustworthiness across social contexts Evol. Hum. Behav. 2017 38 506 512
88. Schild, C., Stern, J., Penke, L. & Zettler, I. Voice pitch—a valid indicator of one’s unfaithfulness in committed relationships? Adapt. Hum. Behav. Physiol.. 10.1007/s40750-020-00154-0 (2020).
89. O’Connor JJM Pisanski K Tigue CC Fraccaro PJ Feinberg DR Perceptions of infidelity risk predict women’s preferences for low male voice pitch in short-term over long-term relationship contexts Personal. Individ. Differ. 2014 56 73 77
90. Gangestad SW Simpson JA The evolution of human mating: trade-offs and strategic pluralism Behav. Brain Sci. 2000 23 573 587 11301543
91. Titze IR Principles of Voice Production 1994 Upper Saddle River Prentice Hall
92. Stulp G Pollet TV Verhulst S Buunk AP A curvilinear effect of height on reproductive success in human males Behav. Ecol. Sociobiol. 2012 66 375 384 22389549
93. Maner, J. K. & Case, C. R. Dominance and prestige: dual strategies for navigating social hierarchies. in Advances in Experimental Social Psychology (eds. Olson, J. M. & Zanna, M. P.) vol. 54 129–180 (Academic Press, 2016).
94. Zaidi AA Facial masculinity does not appear to be a condition-dependent male ornament and does not reflect MHC heterozygosity in humans Proc. Natl. Acad. Sci. 2019 116 1633 1638 30647112
95. Kordsmeyer TL Penke L Effects of male testosterone and its interaction with cortisol on self- and observer-rated personality states in a competitive mating context J. Res. Personal. 2019 78 76 92
96. Faul F Erdfelder E Buchner A Lang A-G Statistical power analyses using G*Power 3.1: tests for correlation and regression analyses Behav. Res. Methods 2009 41 1149 1160 19897823
97. Mahrholz G Belin P McAleer P Judgements of a speaker’s personality are correlated across differing content and stimulus type PLoS ONE 2018 13 e0204991 30286148
98. Boersma, P. & Weenink, D. Praat: doing phonetics by computer. (2018).
99. Idris FP Wan Y Zhang X Punyadeera C Within-day baseline variation in salivary biomarkers in healthy men OMICS J. Integr. Biol. 2017 21 74 80
100. Schultheiss, O. C. & Stanton, S. J. Assessment of salivary hormones. in Methods in social neuroscience 17–44 (eds. Harmon-Jones, E. & Beer J.S.) (Guilford Press, New York, NY 2009).
101. Granger DA Shirtcliff EA Booth A Kivlighan KT Schwartz EB The, “trouble” with salivary testosterone Psychoneuroendocrinology 2004 29 1229 1240 15288702
102. Mehta PH Welker KM Zilioli S Carré JM Testosterone and cortisol jointly modulate risk-taking Psychoneuroendocrinology 2015 56 88 99 25813123
103. Kordsmeyer TL Stern J Penke L 3D anthropometric assessment and perception of male body morphology in relation to physical strength Am. J. Hum. Biol. 2019 31 e23276 31211470
104. Price ME Dunn J Hopkins S Kang J Anthropometric correlates of human anger Evol. Hum. Behav. 2012 33 174 181
105. Sell A Human adaptations for the visual assessment of strength and fighting ability from the body and face Proc. R. Soc. B Biol. Sci. 2009 276 575 584
106. Team, R. C. R: A Language and Environment for Statistical Computing. (Vienna, Austria, 2013).
107. Wickham, H. et al. Ggplot2: create elegant data visualisations using the grammar of graphics. (2020).
108. Hittner JB May K Silver NC A Monte Carlo evaluation of tests for comparing dependent correlations J. Gen. Psychol. 2003 130 149 168 12773018
109. Lenth, R. rsm: Response-Surface Analysis. (2020).
110. Viechtbauer, W. metafor: Meta-Analysis Package for R. (2020).
111. Hayes AF Introduction to Mediation, Moderation, and Conditional Process Analysis: A Regression-Based Approach 2013 New York The Guilford Press
112. Raiche, G. & Magis, D. nFactors: Parallel analysis and other non graphical solutions to the cattell scree test. (2020).
113. Revelle, W. psych: Procedures for Psychological, Psychometric, and Personality Research. (2020).
114. Zakzanis KK Statistics to tell the truth, the whole truth, and nothing but the truth Formulae, illustrative numerical examples, and heuristic interpretation of effect size analyses for neuropsychological researchers Arch. Clin. Neuropsychol. 2001 16 653 667 14589784
115. Brunswik E The Conceptual Framework of Psychology 1952 Chicago University of Chicago Press
116. Zhang J Zheng L Zhang S Xu W Zheng Y Vocal characteristics predict infidelity intention and relationship commitment in men but not in women Personal. Individ. Differ. 2021 168 110389
117. Li Y Women’s preference for masculine traits is disrupted by images of male-on-female aggression PLoS ONE 2014 9 e110497 25314277
118. Borras-Guevara ML Batres C Perrett DI Aggressor or protector? Experiences and perceptions of violence predict preferences for masculinity Evol. Hum. Behav. 2017 38 481 489
119. Dejonckere PH Differentiated perceptual evaluation of pathological voice quality: reliability and correlations with acoustic measurements Rev. Laryngol. Otol. Rhinol. 1996 117 219 224
120. Michaelis D Fröhlich M Strube HW Selection and combination of acoustic features for the description of pathologic voices J. Acoust. Soc. Am. 1998 103 1628 1639 9514027
121. Virginia W James F Richard C Acoustic prediction of severity in commonly occurring voice problems J . Speech Lang. Hear. Res. 1995 38 273 279
122. Puts, D. A., Doll, L. M. & Hill, A. K. Sexual selection on human voices. in Evolutionary Perspectives on Human Sexual Psychology and Behavior (eds. Weekes-Shackelford, V. A. & Shackelford, T. K.) 69–86 (Springer, Berlin, 2014).
123. Cheng JT Tracy JL Ho S Henrich J Listen, follow me: Dynamic vocal signals of dominance predict emergent social rank in humans J. Exp. Psychol. Gen. 2016 145 536 547 27019023
124. Altman DG Royston P The cost of dichotomising continuous variables BMJ 2006 332 1080 16675816
125. Leary CJ Knapp R The stress of elaborate male traits: integrating glucocorticoids with androgen-based models of sexual selection Anim. Behav. 2014 89 85 92
126. Sapolsky RM Romero LM Munck AU How do glucocorticoids influence stress responses? Integrating permissive, suppressive, stimulatory, and preparative actions Endocr. Rev. 2000 21 55 89 10696570
127. Roberts ML Buchanan KL Hasselquist D Evans MR Effects of testosterone and corticosterone on immunocompetence in the zebra finch Horm. Behav. 2007 51 126 134 17049519
128. Kandrik M Does the interaction between cortisol and testosterone predict men’s facial attractiveness? Adapt. Hum. Behav. Physiol. 2017 3 275 281
129. Dekkers TJ A meta-analytical evaluation of the dual-hormone hypothesis: does cortisol moderate the relationship between testosterone and status, dominance, risk taking, aggression, and psychopathy? Neurosci. Biobehav. Rev. 2019 96 250 271 30529754
130. Grebe NM Testosterone, cortisol, and status-striving personality features: a review and empirical evaluation of the Dual Hormone hypothesis Horm. Behav. 2019 109 25 37 30685468
131. Feinberg DR Jones BC Armstrong MM Sensory exploitation, sexual dimorphism, and human voice pitch Trends Ecol. Evol. 2018 33 901 903 30287080
132. Dawkins MS Guilford T The corruption of honest signalling Anim. Behav. 1991 41 865 873
133. Andersson M Why are there so many threat displays? J. Theor. Biol. 1980 86 773 781 7195963
134. Giddens CL Barron KW Byrd-Craven J Clark KF Winter AS Vocal indices of stress: a review J. Voice 2013 27 390 e21 390.e29
135. Zhang, J. et al. Elevated recognition accuracy for low-pitched male voices in men with higher threat potential: Further evidence for the retaliation-cost model in humans. Evol. Hum. Behav. (2020).136.Zhang, J. & Reid, S. A. Aggression in young men high in threat potential increases after hearing low-pitched male voices: two tests of the retaliation-cost model. Evol. Hum. Behav. 38, 513–521 (2020).
136. Zhang J Reid SA Aggression in young men high in threat potential increases after hearing low-pitched male voices: two tests of the retaliation-cost model Evol. Hum. Behav. 2017 38 513 521
137. Lakens, D. One-sided tests: Efficient and underused. The 20% Statistician https://daniellakens.blogspot.com/2016/03/one-sided-tests-efficient-and-underused.html (2016).