Harsh is large: nonlinear vocal phenomena lower voice pitch and exaggerate body size

A lion's roar, a dog's bark, an angry yell in a pub brawl: what do these vocalizations have in common? They all sound harsh due to nonlinear vocal phenomena (NLP) - deviations from regular voice production, hypothesized to lower perceived voice pitch and thereby exaggerate the apparent body size of the vocalizer. To test this yet uncorroborated hypothesis, we synthesized human nonverbal vocalizations, such as roars, groans and screams, with and without NLP (amplitude modulation, subharmonics and chaos). We then measured their effects on nearly 700 listeners' perceptions of three psychoacoustic (pitch, timbre, roughness) and three ecological (body size, formidability, aggression) characteristics. In an explicit rating task, all NLP lowered perceived voice pitch, increased voice darkness and roughness, and caused vocalizers to sound larger, more formidable and more aggressive. Key results were replicated in an implicit associations test, suggesting that the 'harsh is large' bias will arise in ecologically relevant confrontational contexts that involve a rapid, and largely implicit, evaluation of the opponent's size. In sum, nonlinearities in human vocalizations can flexibly communicate both formidability and intention to attack, suggesting they are not a mere byproduct of loud vocalizing, but rather an informative acoustic signal well suited for intimidating potential opponents

Friend or foe:Risso’s dolphins eavesdrop on conspecific sounds to induce or avoid intra-specific interaction

The detection and use of emitters’ signals by unintended receivers, i.e., eavesdropping, represents an important and often low-cost way for animals to gather information from their environment. Acoustic eavesdropping can be a key driver in mediating intra- and interspecific interactions (e.g., cooperation, predator–prey systems), specifically in species such as cetaceans that use sound as a primary sensory modality. While most cetacean species produce context-specific sounds, little is known about the use of those sounds by potential conspecific eavesdroppers. We experimentally tested the hypothesis that a social cetacean, Risso’s dolphin (Grampus griseus), is able to gather biologically relevant information by eavesdropping on conspecific sounds. We conducted playback experiments on free-ranging dolphins using three context-specific sounds stimuli and monitored their horizontal movement using visual or airborne focal follow observations. We broadcasted natural sequences of conspecific foraging sounds potentially providing an attractive dinner bell signal (n = 7), male social sounds simulating a risk of forthcoming agonistic interaction (n = 7) and female-calf social sounds representing no particularly threatening context (n = 7). We developed a quantitative movement response score and tested whether animals changed their direction of horizontal movement towards or away from the playback source. Dolphins approached the foraging and the social female-calf sounds whereas they avoided the social male sounds. Hence, by acoustically eavesdropping on conspecifics, dolphins can discriminate between social and behavioural contexts and anticipate potential threatening or beneficial situations. Eavesdropping and the ensuing classification of ‘friend or foe’ can thus shape intra-specific social interactions in cetaceans

Evidence for discrimination between feeding sounds of familiar fish and unfamiliar mammal-eating killer whale ecotypes by long-finned pilot whales

Research funding was provided by the US Office of Naval Research, the DGA/TN (France), the UK Natural Environmental Research Council, and the Ministries of Defence of Norway and The Netherlands. PLT acknowledges funding received from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). MASTS is funded by the Scottish Funding Council (Grant reference HR09011) and contributing institutions. CC acknowledges statistical support provided by the Multi-study OCean acoustics Human effects Analysis (MOCHA) project funded by the United States Office of Naval Research (Grant N00014-12-1-0204).Killer whales (KW) may be predators or competitors of other cetaceans. Since their foraging behavior and acoustics differ among populations ('ecotypes'), we hypothesized that other cetaceans can eavesdrop on KW sounds and adjust their behavior according to the KW ecotype. We performed playback experiments on long-finned pilot whales (Globicephala melas) in Norway using familiar fish-eating KW sounds (fKW) simulating a sympatric population that might compete for foraging areas, unfamiliar mammal-eating KW sounds (mKW) simulating a potential predator threat, and two control sounds. We assessed behavioral responses using animal-borne multi-sensor tags and surface visual observations. Pilot whales barely changed behavior to a broadband noise (CTRL-), whereas they were attracted and exhibited spyhops to fKW, mKW, and to a repeated-tonal upsweep signal (CTRL+). Whales never stopped nor started feeding in response to fKW, whereas they reduced or stopped foraging to mKW and CTRL+. Moreover, pilot whales joined other subgroups in response to fKW and CTRL+, whereas they tightened individual spacing within group and reduced time at surface in response to mKW. Typical active intimidation behavior displayed to fKW might be an antipredator strategy to a known low-risk ecotype or alternatively a way of securing the habitat exploited by a heterospecific sympatric population. Cessation of feeding and more cohesive approach to mKW playbacks might reflect an antipredator behavior towards an unknown KW ecotype of potentially higher risk. We conclude that pilot whales are able to acoustically discriminate between familiar and unfamiliar KW ecotypes, enabling them to adjust their behavior according to the perceived disturbance type.PostprintPeer reviewe

Communication d’informations statiques et dynamiques via les vocalisations des chiots (Canis familairis)

In vertebrates, in order to provide optimal care to their young, parents use their vocal signals to assess kin, individuality or dynamic need. Despite the fact that many highly accessible species of domesticated mammals, that produce large and highly vocal litters, provide an ideal model for studying the mechanisms underlying such multilevel communication, they remain largely under-investigated. In this thesis, I aim to fill this gap by investigating the production and the perception of such information in the offspring calls of domestic dogs, a large litter-rearing mammal.I show that puppy whines contain litter and individual signatures mainly predicted by fundamental frequency fo. Playbacks experiments of whines also indicate that mothers use fo to recognise for their litter and puppies. Then, I move on to the investigation of vocal indicators of short-term need. My results demonstrate that nonlinear phenomena can reflect high level of need of puppies and that human caregivers are particularly sensitive to these harsh and salient perceptual cues of whines. In sum, my thesis work provides evidence for the acoustic encoding of multilevel static and dynamic information in a single call type, that mediate the interaction between offspring and their caregivers, and may facilitate the provision of optimal care.Chez les vertébrés, il est bien établi que les parents utilisent les signaux vocaux de leur jeune afin de le reconnaitre et d’évaluer ses besoins pour lui fournir des soins adaptés. Ces mécanismes de communication sont très peu décrits chez les espèces de mammifères qui produisent des portées malgré le fait qu’elles constituent un modèle idéal pour étudier la complexité de l’information multi-niveau (parenté, individu, besoins). Ainsi, l’objectif de ma thèse est d’étudier la production et la perception des informations encodées dans les pleurs des chiots ; un mammifère donnant naissance à de large portées composées de jeunes très vocaux dès la naissance. Je montre que les pleurs des chiots contiennent une signature vocale de portée et une signature individuelle, principalement prédite par leur fréquence fondamentale fo. Des expériences de repasse acoustique consistant à diffuser des pleurs de chiot, dont la fo est modifiée, indiquent également que ce paramètre est important pour la reconnaissance de la portée et des chiots par la mère. Ensuite, mes résultats montrent que les phénomène non linéaires communiquent des informations liées sur l’état émotionnel des chiots et que les humains y sont particulièrement sensibles. Mon travail de thèse démontre que des informations statiques et dynamiques riches sont simultanément encodées dans un seul type de cri chez le jeune chiot. Je suggère que cette communication complexe d’informations facilite la provision de soins adaptés

Communication d’informations statiques et dynamiques via les vocalisations des chiots (Canis familairis)

In vertebrates, in order to provide optimal care to their young, parents use their vocal signals to assess kin, individuality or dynamic need. Despite the fact that many highly accessible species of domesticated mammals, that produce large and highly vocal litters, provide an ideal model for studying the mechanisms underlying such multilevel communication, they remain largely under-investigated. In this thesis, I aim to fill this gap by investigating the production and the perception of such information in the offspring calls of domestic dogs, a large litter-rearing mammal.I show that puppy whines contain litter and individual signatures mainly predicted by fundamental frequency fo. Playbacks experiments of whines also indicate that mothers use fo to recognise for their litter and puppies. Then, I move on to the investigation of vocal indicators of short-term need. My results demonstrate that nonlinear phenomena can reflect high level of need of puppies and that human caregivers are particularly sensitive to these harsh and salient perceptual cues of whines. In sum, my thesis work provides evidence for the acoustic encoding of multilevel static and dynamic information in a single call type, that mediate the interaction between offspring and their caregivers, and may facilitate the provision of optimal care.Chez les vertébrés, il est bien établi que les parents utilisent les signaux vocaux de leur jeune afin de le reconnaitre et d’évaluer ses besoins pour lui fournir des soins adaptés. Ces mécanismes de communication sont très peu décrits chez les espèces de mammifères qui produisent des portées malgré le fait qu’elles constituent un modèle idéal pour étudier la complexité de l’information multi-niveau (parenté, individu, besoins). Ainsi, l’objectif de ma thèse est d’étudier la production et la perception des informations encodées dans les pleurs des chiots ; un mammifère donnant naissance à de large portées composées de jeunes très vocaux dès la naissance. Je montre que les pleurs des chiots contiennent une signature vocale de portée et une signature individuelle, principalement prédite par leur fréquence fondamentale fo. Des expériences de repasse acoustique consistant à diffuser des pleurs de chiot, dont la fo est modifiée, indiquent également que ce paramètre est important pour la reconnaissance de la portée et des chiots par la mère. Ensuite, mes résultats montrent que les phénomène non linéaires communiquent des informations liées sur l’état émotionnel des chiots et que les humains y sont particulièrement sensibles. Mon travail de thèse démontre que des informations statiques et dynamiques riches sont simultanément encodées dans un seul type de cri chez le jeune chiot. Je suggère que cette communication complexe d’informations facilite la provision de soins adaptés

Communication d’informations statiques et dynamiques via les vocalisations des chiots (Canis familairis)

Chez les vertébrés, il est bien établi que les parents utilisent les signaux vocaux de leur jeune afin de le reconnaitre et d’évaluer ses besoins pour lui fournir des soins adaptés. Ces mécanismes de communication sont très peu décrits chez les espèces de mammifères qui produisent des portées malgré le fait qu’elles constituent un modèle idéal pour étudier la complexité de l’information multi-niveau (parenté, individu, besoins). Ainsi, l’objectif de ma thèse est d’étudier la production et la perception des informations encodées dans les pleurs des chiots ; un mammifère donnant naissance à de large portées composées de jeunes très vocaux dès la naissance. Je montre que les pleurs des chiots contiennent une signature vocale de portée et une signature individuelle, principalement prédite par leur fréquence fondamentale fo. Des expériences de repasse acoustique consistant à diffuser des pleurs de chiot, dont la fo est modifiée, indiquent également que ce paramètre est important pour la reconnaissance de la portée et des chiots par la mère. Ensuite, mes résultats montrent que les phénomène non linéaires communiquent des informations liées sur l’état émotionnel des chiots et que les humains y sont particulièrement sensibles. Mon travail de thèse démontre que des informations statiques et dynamiques riches sont simultanément encodées dans un seul type de cri chez le jeune chiot. Je suggère que cette communication complexe d’informations facilite la provision de soins adaptés.In vertebrates, in order to provide optimal care to their young, parents use their vocal signals to assess kin, individuality or dynamic need. Despite the fact that many highly accessible species of domesticated mammals, that produce large and highly vocal litters, provide an ideal model for studying the mechanisms underlying such multilevel communication, they remain largely under-investigated. In this thesis, I aim to fill this gap by investigating the production and the perception of such information in the offspring calls of domestic dogs, a large litter-rearing mammal.I show that puppy whines contain litter and individual signatures mainly predicted by fundamental frequency fo. Playbacks experiments of whines also indicate that mothers use fo to recognise for their litter and puppies. Then, I move on to the investigation of vocal indicators of short-term need. My results demonstrate that nonlinear phenomena can reflect high level of need of puppies and that human caregivers are particularly sensitive to these harsh and salient perceptual cues of whines. In sum, my thesis work provides evidence for the acoustic encoding of multilevel static and dynamic information in a single call type, that mediate the interaction between offspring and their caregivers, and may facilitate the provision of optimal care

Communication d’informations statiques et dynamiques via les vocalisations des chiots (Canis familairis)

In vertebrates, in order to provide optimal care to their young, parents use their vocal signals to assess kin, individuality or dynamic need. Despite the fact that many highly accessible species of domesticated mammals, that produce large and highly vocal litters, provide an ideal model for studying the mechanisms underlying such multilevel communication, they remain largely under-investigated. In this thesis, I aim to fill this gap by investigating the production and the perception of such information in the offspring calls of domestic dogs, a large litter-rearing mammal.I show that puppy whines contain litter and individual signatures mainly predicted by fundamental frequency fo. Playbacks experiments of whines also indicate that mothers use fo to recognise for their litter and puppies. Then, I move on to the investigation of vocal indicators of short-term need. My results demonstrate that nonlinear phenomena can reflect high level of need of puppies and that human caregivers are particularly sensitive to these harsh and salient perceptual cues of whines. In sum, my thesis work provides evidence for the acoustic encoding of multilevel static and dynamic information in a single call type, that mediate the interaction between offspring and their caregivers, and may facilitate the provision of optimal care.Chez les vertébrés, il est bien établi que les parents utilisent les signaux vocaux de leur jeune afin de le reconnaitre et d’évaluer ses besoins pour lui fournir des soins adaptés. Ces mécanismes de communication sont très peu décrits chez les espèces de mammifères qui produisent des portées malgré le fait qu’elles constituent un modèle idéal pour étudier la complexité de l’information multi-niveau (parenté, individu, besoins). Ainsi, l’objectif de ma thèse est d’étudier la production et la perception des informations encodées dans les pleurs des chiots ; un mammifère donnant naissance à de large portées composées de jeunes très vocaux dès la naissance. Je montre que les pleurs des chiots contiennent une signature vocale de portée et une signature individuelle, principalement prédite par leur fréquence fondamentale fo. Des expériences de repasse acoustique consistant à diffuser des pleurs de chiot, dont la fo est modifiée, indiquent également que ce paramètre est important pour la reconnaissance de la portée et des chiots par la mère. Ensuite, mes résultats montrent que les phénomène non linéaires communiquent des informations liées sur l’état émotionnel des chiots et que les humains y sont particulièrement sensibles. Mon travail de thèse démontre que des informations statiques et dynamiques riches sont simultanément encodées dans un seul type de cri chez le jeune chiot. Je suggère que cette communication complexe d’informations facilite la provision de soins adaptés

Are there individual differences in dog calls before two months of age?

International audienceWhile recent studies of dog (Canis familiairis) vocal communication have considerably improved our understanding of the intra- and inter-specific function of this domestic species’ vocalisations, these studies have largely focussed on the vocal behaviour of adult dogs. As such, the origins and development of static (e.g. size, age, dominance…) and dynamic (e.g. motivation or emotions) vocal cues remain poorly understood. Here, we investigated whether the fundamental frequency (F0) of puppies’ isolation calls provides static cues to age and body weight before two months of age. We recorded whines of Beagle puppies (N=26 from 5 litters) during their 3rd,6th and 9th week of life. We recorded 2800 whines while individual puppies were temporally isolated from their mothers and littermates. We then analysed the F0 mean, F0 range and F0 contour of these calls and used linear mixed models to test the effect of age and body weight on these parameters. Preliminary results indicate that, while (within each litter) the mean F0 is negatively correlated with body weight at 3 weeks of age, this effect disappears at 6 and 9 weeks of age. Our preliminary investigation thus suggests the F0 mean may provide mothers with reliable information on puppy condition during the breastfeeding phase. Future work will investigate the possible function of this information, as well as the longitudinal trajectories in call F0 until adulthood

Nonlinear vocal phenomena affect human perceptions of distress, size and dominance in puppy whines

International audienceWhile nonlinear phenomena (NLP) are widely reported in animal vocalizations, often causing perceptual harshness and roughness, their communicative function remains debated. Several hypotheses have been put forward: attention-grabbing, communication of distress, exaggeration of body size and dominance. Here, we use state-of-the-art sound synthesis to investigate how NLP affect the perception of puppy whines by human listeners. Listeners assessed the distress, size or dominance conveyed by synthetic puppy whines with manipulated NLP, including frequency jumps and varying proportions of subharmonics, sidebands and deterministic chaos. We found that the presence of chaos increased the puppy's perceived level of distress and that this effect held across a range of representative fundamental frequency ( f o ) levels. Adding sidebands and subharmonics also increased perceived distress among listeners who have extensive caregiving experience with pre-weaned puppies (e.g. breeders, veterinarians). Finally, we found that whines with added chaos, subharmonics or sidebands were associated with larger and more dominant puppies, although these biases were attenuated in experienced caregivers. Together, our results show that nonlinear phenomena in puppy whines can convey rich information to human listeners and therefore may be crucial for offspring survival during breeding of a domesticated species