(A) Vocalization minimum frequency as a function of species body mass for terrestrial (n = 105), semiaquatic (n = 23), and aquatic (n = 42) environments on a log scale. The dotted line represents the phylogenetic generalized least squares (PGLS) regression line for terrestrial mammals log(Y) =-0.41log(X)-0.21 (CI-0.50,-0.32) the dash-dot line represents semiaquatic mammals log(Y) =-0.41log(X) + 0.06 (CI-0.50,-0.32) and the solid line for aquatic mammals log(Y) =-0.41log(X) + 0.93 (CI-0.50,-0.32). (B) Vocalization maximum frequency as a function of species body mass for terrestrial (n = 125), semiaquatic (n = 23), and aquatic (n = 41) environments on a log scale. Terrestrial mammals log(Y) =-0.38log(X) + 0.98 (CI-0.34,-0.06), semiaquatic mammals log(Y) =-0.18log(X) + 1.13 (CI-0.28, 0.45), and aquatic mammals log(Y) =-0.18log(X) + 1.63 (CI-0.31,-0.06). Silhouettes by Oscar Sanisidro and Chris Huh were downloaded from http://phylopic.org. 

(A) Vocalization minimum frequency as a function of species body mass for terrestrial (n = 105), semiaquatic (n = 23), and aquatic (n = 42) environments on a log scale. The dotted line represents the phylogenetic generalized least squares (PGLS) regression line for terrestrial mammals log(Y) =-0.41log(X)-0.21 (CI-0.50,-0.32) the dash-dot line represents semiaquatic mammals log(Y) =-0.41log(X) + 0.06 (CI-0.50,-0.32) and the solid line for aquatic mammals log(Y) =-0.41log(X) + 0.93 (CI-0.50,-0.32). (B) Vocalization maximum frequency as a function of species body mass for terrestrial (n = 125), semiaquatic (n = 23), and aquatic (n = 41) environments on a log scale. Terrestrial mammals log(Y) =-0.38log(X) + 0.98 (CI-0.34,-0.06), semiaquatic mammals log(Y) =-0.18log(X) + 1.13 (CI-0.28, 0.45), and aquatic mammals log(Y) =-0.18log(X) + 1.63 (CI-0.31,-0.06). Silhouettes by Oscar Sanisidro and Chris Huh were downloaded from http://phylopic.org. 

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Previous studies of the vocalisation frequencies of mammals have suggested that it is either body mass or environment that drives these frequencies. Using 193 species across the globe from the terrestrial and aquatic environments and a model selection approach, we identified that the best supported model for minimum and maximum frequencies for voca...

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... Alternatively, several studies have shown that humpback whales increase their calling rate when unaffiliated whales join the group (Silber, 1986;Rekdahl et al., 2015;Cusano et al., 2020), and it has been proposed that variable call rates across escorted groups are attributable to the presence of males and differences in behavioral context (Seger, 2016, dissertation). Additionally, acoustic features of calls may relay physical attributes of the signaler to conspecifics, because the minimum frequency of calls in mysticete whales is somewhat limited by animal size (May-Collado et al., 2007;Martin et al., 2017). ...
... The contribution of calf calls could potentially contribute to increasing the frequency levels of calls in these groups. To an extent, the minimum frequency of calls in mysticete whales is limited by animal size (May-Collado et al., 2007;Martin et al., 2017), with smaller animals possibly being incapable of producing the lowest frequency calls. It is possible that a balance between calf calls, which are generally produced at higher frequencies than those of adults (Zoidis et al., 2008;Indeck et al., 2020), and calls from the adults in these groups, contributed to the frequency values observed Frequency measurements were relatively consistent with expected patterns, which was also true for observed call durations. ...
... However, dyads, which were not observed interacting aggressively, were expected to have the shortest call durations, which were instead exhibited by escorted mother-calf pairs. It is possible, however, that the duration of calls could have been affected by the physical attributes of the signaler (i.e., body size, age class, vocal ontogeny/calling experience; Martin et al., 2017), rather than the dynamics of the group. ...
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Humpback whales (Megaptera novaeangliae) are exceptionally vocal among baleen whale species. While extensive research has been conducted on humpback whale songs, gaps remain in our understanding of other forms of communication, particularly non-song calls. Here, we compare the spectral features and temporal parameters of non-song calls recorded from Acousonde tagged humpback whales in three commonly observed group types in the breeding grounds: adult dyads (N = 3), singly escorted mother-calf pairs (N = 4), and competitive groups (N = 4). Recordings were collected off Maui, Hawai’i during the winter breeding seasons of 2019–2021. Individual calls were identified based on visual and aural inspection of spectrograms using Raven Pro 1.6 software, with a total of 842 calls isolated from 47.6 h of acoustic recordings. Competitive groups produced the most calls (N = 358); however, after adjusting for the differences in recording hours and the number of individuals, the call rate (calls/hour/whale) was not significantly different between group compositions. The temporal parameters and frequency measures of calls did not vary significantly across the groups. However, interesting patterns of calling behavior were observed (e.g., competitive groups had the shortest inter-call intervals and the highest frequency calls, and escorted mother-calf pairs had the longest inter-call intervals) and it is possible the lack of statistical significance could be attributed to the small sample size of tag deployments. This study provides new insights into humpback whale vocal communication behavior in the Hawaiian Islands breeding grounds.
... The human auditory range is limited, and mammals frequently produce and perceive sound at frequencies beyond human auditory abilities (Heffner and Heffner, 2018). Both infrasound and ultrasound are used by mammals in terrestrial and aquatic habitats (Martin et al., 2017) and detection of these vocalizations require specialized bioacoustics monitoring equipment and this fact may help to explain the paucity of data (Ladich and Winkler, 2017;Romero-Mujalli et al., 2021). ...
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Temporally coordinated interactive vocalizations are important means of communication between individuals in various animal taxa. In mammals, interactive calling and singing can be highly synchronized to create either overlapping or antiphonal duets while in others, competitors antagonistically vocalize, engaging in counter-singing. Among non-primate mammals these vocalizations are considered rare and poorly understood. We provide an overview of antiphonal calling, duetting and counter-singing in non-primate mammals. Many of these coordinated vocalizations play a role in social interactions and allow mammals to convey information to other members of the social unit in visually inaccessible environments. South American Bamboo rats Dactylomys spp. are arboreal bamboo specialists found in dense bamboo thickets in Bolivia, Peru, Ecuador, Brazil and Colombia. These nocturnal rodents are rarely seen but can be easily heard because of their loud and distinctive staccato vocalizations. We provide some evidence that Bamboo rats engage in duetting, and as such they provide another case of a mammalian species, in which to investigate temporally coordinated interactive singing. We urge researchers to work toward common definitions of temporally coordinated vocalizations and to search for more mammals that utilize such vocalizations.
... Along these lines, Bowling et al. (2017) found a negative correlation between "head + body size" and vocalization frequencies across a range of carnivore and primate species. Similarly, Martin et al. (2017) showed that body weightanother operationalization of body size -is an important determinant of minimum vocalization frequency in different terrestrial and aquatic mammal species. Analogous results were also reported by Riede and Brown (2013) based on their analysis of F 0 vs. body weight in different mammal species, and more recently, Aung et al. (2021a) also reported negative associations of F 0 and P f with both height and weight. ...
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Animal vocalizations convey important information about the emitter, including sex, age, biological quality, and emotional state. Early on, Darwin proposed that sex differences in auditory signals and vocalizations were driven by sexual selection mechanisms. In humans, studies on the association between male voice attributes and physical formidability have thus far reported mixed results. Hence, with a view to furthering our understanding of the role of human voice in advertising physical formidability, we sought to identify acoustic attributes of male voices associated with physical formidability proxies. Mean fundamental frequency (F0), formant dispersion (Df), formant position (Pf), and vocal tract length (VTL) data from a sample of 101 male voices was analyzed for potential associations with height, weight, and maximal handgrip strength (HGS). F0 correlated negatively with HGS; Pf showed negative correlations with HGS, height and weight, whereas VTL positively correlated with HGS, height and weight. All zero-order correlations remained significant after controlling for false discovery rate (FDR) with the Benjamini–Hochberg method. After controlling for height and weight—and controlling for FDR—the correlation between F0 and HGS remained significant. In addition, to evaluate the ability of human male voices to advertise physical formidability to potential mates, 151 heterosexual female participants rated the voices of the 10 strongest and the 10 weakest males from the original sample for perceived physical strength, and given that physical strength is a desirable attribute in male partners, perceived attractiveness. Generalized linear mixed model analyses—which allow for generalization of inferences to other samples of both raters and targets—failed to support a significant association of perceived strength or attractiveness from voices alone and actual physical strength. These results add to the growing body of work on the role of human voices in conveying relevant biological information.
... The blue whale song production is probably of a source-filter type (Reidenberg, 2017;Patris et al., 2019). In numerous species producing vocalizations of this type, and especially in mammals, the song's peak frequencies (selected by the formants of the vocal filter) and fundamental frequencies are positively correlated with the size of the vocalizing system, which is itself correlated with the size of the animal (Pfefferle and Fischer, 2006;Sanvito et al., 2007;Reby et al., 2010;Martin et al., 2016). In some species, low frequency vocalizations of males have been shown to be linked to dominant positions (Vannoni and McElligott, 2008) or enhanced attraction of females (Searcy and Andersson, 1986). ...
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The linear decrease in the frequency of blue whale songs around the world is, to date, an unexplained phenomenon. We show it can be reproduced by a mathematical model considering two antagonistic behavioral trends: first, a bias towards conformity in the song, and second, a tendency to try and sing lower than the other whales. We check the robustness of our model by considering some more complex premises. First, different hierarchical relations between the singers are explored, adapting methods used in the flocking motion studies. Then a population-dependant simulation shows that even considering the gradual addition of new whales, the evolution is still globally linear. Finally, we show that intra-annual variations surging from different causes can be naturally incorporated into the model. We then conclude that, unlike other explanations, a cultural hypothesis seems compatible with the observed linearity of the blue whales's songs frequency shift.
... This common neural control would determine that the vocalizations of armadillos share general acoustic features. Otherwise, ecological selection for body size and habitat type represents a potential driver of the acoustic divergence among their vocalizations (Martin et al. 2017). Firstly, the notable size differences between species (e.g., C. retusus ~100 g; C. chacoensis ~1,500 g: Superina and Abba 2018) and, particularly, differences in their vocal production apparatus, are predicted to covary with the degree of acoustic differentiation between armadillos. ...
Article
Distress vocalizations are emitted by animals experiencing extreme physical distress, such as when caught by a predator. These signals are emitted by numerous and phylogenetically distant vertebrate species and are composed of sequences of broadband and high-amplitude notes. In this study, we provide the frst acoustic characterization of distress vocalizations in four armadillo species: pink fairy armadillo (Chlamyphorus truncatus), greater fairy armadillo (Calyptophractus retusus), Southern three-banded armadillo (Tolypeutes matacus), and Chacoan naked-tailed armadillo (Cabassous chacoensis). We also recharacterized the weeping call of the screaming hairy armadillo (Chaetophractus vellerosus) to compare vocalizations, discuss potential homologies, and examine possible causes of structural and acoustic similarities among these species. In three species the vocalizations were sequences of exhaled notes that differed in their fne spectral structure (exhaled harmonic notes in C. retusus, and exhaled harsh notes in C. truncatus and T. matacus). The vocalization of C. chacoensis was composed of exhaled harsh and inhaled harsh notes that occurred alternately and continuously in a quick sequence. Based on the mode of production and acoustic similarity, we propose that the notes of C. retusus and C. truncatus would be homologous to the conspicuous crying notes of C. vellerosus. The exhaled harsh notes of T. matacus and C. chacoensis may also be homologous to the crying notes of C. vellerosus, but the notes of T. matacus are quite different in various acoustic parameters. Furthermore, the inhaled and exhaled harsh notes of C. chacoensis are similar to the inhaled and exhaled sobbing notes of C. vellerosus, making assessments of homologies uncertain in these species. Because a common motivational state (physical distress) underlies these vocalizations, we propose that the notable differences in body size and habitat preferences of the armadillos could represent potential drivers of the acoustic divergence among their vocalizations.
... In many species, acoustic signals help mediate social interactions such as competition for mates and territory, and parent-offspring recognition (Bradbury and Vehrencamp, 1998;Martin et al., 2017). Signals can encode information about the caller's biology which can be readily deciphered by the receiver, including age (Reby and McComb, 2003;Charlton et al., 2009), sex (Vignal and Kelley, 2007;Charlton et al., 2009), body size (Fitch, 1997;Charlton et al., 2009Charlton et al., , 2011Garcia et al., 2016), hormone levels (Koren and Geffen, 2009) and physical condition (Wyman et al., 2008;Koren and Geffen, 2009). ...
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Acoustic allometry occurs when features of animal vocalisations can be predicted from body size measurements. Despite this being considered the norm, allometry sometimes breaks, resulting in species sounding smaller or larger than expected for their size. A recent hypothesis suggests that allometry-breaking mammals cluster into two groups: those with anatomical adaptations to their vocal tracts and those capable of learning new sounds (vocal learners). Here, we tested which mechanism is used to escape from acoustic allometry by probing vocal tract allometry in a proven mammalian vocal learner, the harbour seal (Phoca vitulina). We tested whether vocal tract structures and body size scale allometrically in 68 young individuals. We found that both body length and body mass accurately predict vocal tract length and one tracheal dimension. Independently, body length predicts vocal fold length while body mass predicts a second tracheal dimension. All vocal tract measures are larger in weaners than in pups and some structures are sexually dimorphic within age classes. We conclude that harbour seals do comply with anatomical allometric constraints. However, allometry between body size and vocal fold length seems to emerge after puppyhood, suggesting that ontogeny may modulate the anatomy–learning distinction previously hypothesised as clear cut. We suggest that seals, and perhaps other species producing signals that deviate from those expected from their vocal tract dimensions, may break allometry without morphological adaptations. In seals, and potentially other vocal learning mammals, advanced neural control over vocal organs may be the main mechanism for breaking acoustic allometry.
... The very high fundamental frequency of the camel 'whistling' HF calls seems to be also disproportionally high for the large body size of the camels: about 600 kg in male C. bactrianus (Nurseitova et al. 2015), over 500 kg in male C. dromedarius (Fatnassi et al. 2014a;Aubè et al. 2017) and over 400 kg in nonpregnant female C. dromedarius (420 kg: Fatnassi et al. 2014a). Following a common rule for relationship between body size and call fundamental frequency in mammals (Fletcher 2004;Charlton and Reby 2016;Martin et al. 2017), the predicted f0 produced by vibration of the vocal folds in the larynx should be substantially lower-frequency for such large-sized animals as camels. So, we can reasonably propose that camels probably produce their high-frequency calls by using another production mode than phonation, most probably the aerodynamic whistle mechanism, recently confirmed for rodents (Riede 2011(Riede , 2013Pasch et al. 2017) and previously proposed also for some ruminants producing high-frequency calls (Frey and Riede 2013;Reby et al. 2016). ...
Article
Among ruminants, some species of cervids, bovids and camelids are capable of producing very high-frequency (HF) calls potentially produced by the aerodynamic whistle mechanism. We analysed the HF calls of six individual adult captive camels: three male and one female two-humped Camelus bactrianus and one male and one female one-humped C. dromedarius. Context of emission differed between sexes and individuals. Males of both species vocalised when guarding females during the rut. Females of both species vocalised towards their mates, postpartum (female C. bactrianus) or when protesting against preventing locomotion over enclosure (female C. dromedarius). In either species or sex, the HF calls were faint tonal vocalisations slightly modulated in fundamental frequency (f0). Between species, the calls were significantly lower-frequency (1.7 ± 0.16 kHz) and longer (0.23 ± 0.08 s) in C. bactrianus than in C. dromedarius (3.12 ± 0.11 kHz; 0.16 ± 0.05 s). Nonlinear vocal phenomena (subharmonics and sidebands) occurred in both species but not in all individuals. We discuss the relationship of the f0 of the HF calls with body size and vocal fold length in ruminants. We conclude that the ‘whistling’ HF calls of C. dromedarius are the highest-frequency vocalisations in Artiodactyla.
... harbour seals, ringed seals P. his - pida, and harp seals P. groenlandica (Terhune 1988(Terhune , 2019, most underwater vocalisations of spotted seals are brief (<1 s) (Beier & Wartzok 1979, Yang et al. 2017. Morphology, particularly of the sound-producing organs, may limit the seal vocalisation length (Martin et al. 2017). Additionally, the number of knock repetitions per train showed a large variability (ranging between 3 and 50), and future work with prolonged recordings will be needed to investigate if spotted seals have the ability to in crease the number of knock repetitions per train (signal redundancy) in more noisy environments (Brumm 2004). ...
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Animals use different strategies to adjust their vocalisations to compensate for ambient noise interference. This is true for some marine mammals, especially cetaceans, but relatively little is known about this for pinnipeds. This study recorded 4 major call types (drum, growl, knock, and sweep) of spotted seals Phoca largha in Liaodong Bay, China, to investigate if seals adjusted their vocalisation parameters in relation to broadband (50 to 4000 Hz) ambient noise recorded immediately preceding each seal vocalisation. Regression analyses showed that the received level of growls, in both broadband (50-4000 Hz) and 1/3-octave bands centred at 200 and 400 Hz, significantly increased with increasing ambient noise levels. These relationships were not observed in the other 3 call types. Further, regardless of call type, the duration, centroid frequency, and root-mean-squared bandwidth parameters showed no statistical relationship with noise levels. The noise measured in this study had relatively low broadband levels of 116 to 132 dB re 1 µPa, and no masking was predicted for any of the 4 call types at 200 and 400 Hz when applying a standard critical ratio approach. It is therefore possible that the ambient noise levels in the study area were not sufficiently loud to induce vocal compensation to avoid masking, but loud enough for the seals to adjust their growl vocalisations. This study is the first to investigate potential vocal adjustment of spotted seals in relation to ambient noise and is important in light of increasing anthropogenic noise in the marine environment.
... Importantly, despite the more labile evolution of sound frequency in songs than calls, we found a stronger allometry of sound frequency for songs than for calls. The negative-slope allometry of sound frequency across species that we found, whereby larger species use lower frequencies, was documented earlier in many taxa [38][39][40] , including for bird songs [41][42][43][44] and calls 45 . But ours is the first work analyzing songs and calls in a sufficiently large number of species to compare the strength of their allometries. ...
Article
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Sexual signals are archetypes of contingent evolution: hyper-diverse across species, often evolving fast and in unpredictable directions. It is unclear to which extent their evolutionary unpredictability weakens deterministic evolution, or takes place bounded by deterministic patterns of trait evolution. We compared the evolution of sound frequency in sexual signals (advertisement songs) and non-sexual social signals (calls) across > 500 genera of the crown songbird families. Contrary to the acoustic adaptation hypothesis, we found no evidence that forest species used lower sound frequencies in songs or calls. Consistent with contingent evolution in song, we found lower phylogenetic signal for the sound frequency of songs than calls, which suggests faster and less predictable evolution, and found unpredictable direction of evolution in lineages with longer songs, which presumably experience stronger sexual selection on song. Nonetheless, the most important deterministic pattern of sound frequency evolution—its negative association with body size—was stronger in songs than calls. This can be explained by songs being longer-range signals than most calls, and thus using sound frequencies that animals of a given size produce best at high amplitude. Results indicate that sexual selection can increase aspects of evolutionary contingency while strengthening, rather than weakening, deterministic patterns of evolution.
... Animals can hear and produce sounds in a wide range of frequencies. Besides taxonomic and anatomic limitations, the specific frequency range produced in mammals broadly depends on their body mass, the environment, and their sociality (or degree of dispersion of the individuals) (Martin et al., 2016). Big sizes, aquatic environments, and high degree of dispersal or separation between individuals are all related to production of lower minimum frequencies. ...
... The source of these sounds can be naturalbiotic (sounds produced by different species) or abiotic (e.g., waves or earthquakes)and anthropogenic (e.g., vessel traffic or fracking). Marine mammals must therefore shape their signals to optimize signal transmission in their oceanic habitats (reviewed in Erbe et al., 2016, Martin et al., 2016. ...
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Humpback whales (𝘔. 𝘯𝘰𝘷𝘢𝘦𝘢𝘯𝘨𝘭𝘪𝘢𝘦) are among the most vocally complex animals. Besides the stereotyped song produced by males mainly during the reproductive season, humpback whales have a diverse repertoire of non-song vocalizations, known as social calls (SCs). These are usually considered random displays, produced in all contexts, regardless of the whales' sex or age, but little is known about calling behavior or call function. Most research on SCs have focus on the Northeast and Southwest Pacific and Northwest Atlantic populations. The SC repertoire and the calling behavior of the humpback whales of the Southeast Pacific (Breeding Stock G) has only been partially documented in two studies. Here two different passive acoustic methodologies (over-the-sides hydrophones and DTAGs) were used to investigate diversity, associated behavior, and context of the Breeding Stock G humpback whales’ SCs in their breeding and feeding grounds. The Stock G catalogue is composed of 48 call types, from which a high percentage are blend and unknown calls. Call rates in the breeding ground of Colombia were higher than in the feeding ground of the Western Antarctic Peninsula. Some call types were frequently found in a competitive context, denoting a possible motivational feature (aggression) of such calls. In Antarctica, a third of the vocal activity was related to surfacing events, and calling behavior was influenced by the presence of conspecifics, the tag (individual), and the period of the day. The results showed that most calls were produced and combined in non-random patterns within bouts. Some of the bouts composed of pulses showed stable structures across time and space similar to bouts reported in allopatric populations. Finally, a new vocal display of repetitive series of cry-like calls, named Repetitive Tones (RTs), is reported in Colombia. Different scenarios about the origin and the function of these calls are discussed. The resemblance of RTs to feeding calls from Alaskan whales may support cross-equatorial displacement between North and Southeastern Pacific populations. The future use of DTAGs in the breeding ground to record SCs and the expanded database of different individuals from Antarctica will allow for deeper analyses of Stock G diversity and calling behavior, better facilitating comparisons between feeding and breeding areas. Community-wide agreements on definition and nomenclature of SCs are necessary for the refinement of the Social Call Global Catalogue and cross-population comparisons.