Katarzyna Pisanski

The evolution of music, language, and prosociality has been debated since before Darwin. The social bonding hypothesis proposes that these phenomena may be interlinked: musicality may have facilitated the evolution of social bonding beyond the possibilities of spoken language. Although dozens of experimental studies have argued that synchronised rhythms can promote bonding, methodological issues including publication bias, sample bias, experimenter effects, and appropriateness of experimental controls make it unclear whether synchronous singing reliably and generally enhances bonding relative to speaking. Following a peer-reviewed Stage 1 Registered Report protocol, we collected data from randomized controlled in-person experiments with 1,017 participants singing and speaking in groups of 5-10 in 30 diverse languages (N = 901 participants after planned quality control exclusions). Our results strongly supported all three of our pre-registered confirmatory hypotheses (all Bayes Factors > 30): (i) synchronised group singing enhances self-reported social bonding (20.9% mean increase), a significantly greater increase than (ii) group conversation (12.9% increase) or (iii) synchronous recitation (15.2% increase). Unregistered exploratory analyses suggested that perceived synchronisation and enjoyment are key predictors of social bonding, results are not artefacts of expectancy or group size, and singing’s bonding effects may be stronger in non-Western than Western contexts. Group singing may serve as a better bonding activity than speaking activities in settings such as school or workplace orientation events. Our study provides strong cross-cultural empirical evidence that music is not merely “auditory cheesecake” that is “useless” compared with language (Pinker, 1997). All forms of vocal communication increase social bonding, but group singing bonds us together over 1.5 times more on average than spoken conversation does.

Psychological studies on close relationships have often overlooked cultural diversity, dynamic processes, and potentially universal principles that shape intimate partnerships. To address the limited generalizability of previous research and advance our understanding of romantic love experiences, mate preferences, and physical attractiveness, we conducted a large-scale cross-cultural survey study on these topics. A total of 404 researchers collected data in 45 languages from April to August 2021, involving 117,293 participants from 175 countries. Aside from standard demographic questions, the survey included valuable information on variables relevant to romantic relationships: intimate, passionate, and committed love within romantic relationships, physical-attractiveness enhancing behaviors, gender equality endorsement, collectivistic attitudes, personal history of pathogenic diseases, relationship quality, jealousy, personal involvement in sexual and/or emotional infidelity, relational mobility, mate preferences, and acceptance of sugar relationships. The resulting dataset provides a rich resource for investigating patterns within, and associations across, a broad range of variables relevant to romantic relationships, with extensive opportunities to analyze individual experiences worldwide.

Nonlinear acoustic phenomena (NLP) likely facilitate the expression of distress in animal vocalizations, making calls perceptually rough and hard to ignore. Yet, their function in adult human vocal communication remains poorly understood. Here, to examine the production and perception of acoustic correlates of pain in spontaneous human nonverbal vocalizations, we take advantage of childbirth—a natural context in which labouring women typically produce a range of highly evocative loud vocalizations, including moans and screams—as they experience excruciating pain. We combine acoustic analyses of these real-life pain vocalizations with psychoacoustic experiments involving the playback of natural and synthetic calls to both naïve and expert listeners. We show that vocalizations become acoustically rougher, higher in fundamental frequency (pitch), less stable, louder and longer as child labour progresses, paralleling a rise in women’s self-assessed pain. In perception experiments, we show that both naïve listeners and obstetric professionals assign the highest pain ratings to vocalizations produced in the final expulsion phase of labour. Experiments with synthetic vocal stimuli confirm that listeners rely largely on nonlinear phenomena to assess pain. Our study confirms that nonlinear phenomena communicate intense, pain-induced distress in humans, consistent with their widespread function to signal distress and arousal in vertebrate vocal signals. This article is part of the theme issue ‘Nonlinear phenomena in vertebrate vocalizations: mechanisms and communicative functions’.

Nonlinear phenomena (NLP) are often associated with high arousal and function to grab attention and/or signal urgency in vocalizations such as distress calls. Although biomechanical models and in vivo / ex vivo experiments suggest that their occurrence reflects the destabilization of vocal fold vibration under intense subglottal pressure and muscle tension, comprehensive descriptions of the dynamics of NLP occurrence in natural vocal signals are critically lacking. Here, to plug this gap, we report the timing, type, extent and acoustic context of NLP in 12 011 whines produced by Beagle puppies ( Canis familiaris ) during a brief separation from their mothers. Within bouts of whines, we show that both the proportion of time vocalizing and the number of whines containing NLP, especially those with chaos, increase with time since separation, presumably reflecting heightened arousal. Within whines, we show that NLP are typically produced during the first half of the call, following the steepest rises in pitch (fundamental frequency, f _o ) and amplitude. While our study reinforces the notion that NLP arise in calls due to instabilities in vocal production during high arousal, it also provides novel and efficient analytical tools for quantifying nonlinear acoustics in ecologically relevant mammal vocal communication contexts. This article is part of the theme issue ‘Nonlinear phenomena in vertebrate vocalizations: mechanisms and communicative functions’.

At some point in our evolutionary history, humans lost vocal membranes and air sacs, representing an unexpected simplification of the vocal apparatus relative to other great apes. One hypothesis is that these simplifications represent anatomical adaptations for speech because a simpler larynx provides a suitably stable and tonal vocal source with fewer nonlinear vocal phenomena (NLP). The key assumption that NLP reduce speech intelligibility is indirectly supported by studies of dysphonia, but it has not been experimentally tested. Here, we manipulate NLP in vocal stimuli ranging from single vowels to sentences, showing that the vocal source needs to be stable, but not necessarily tonal, for speech to be readily understood. When the task is to discriminate synthesized monophthong and diphthong vowels, continuous NLP (subharmonics, amplitude modulation and even deterministic chaos) actually improve vowel perception in high-pitched voices, likely because the resulting dense spectrum reveals formant transitions. Rough-sounding voices also remain highly intelligible when continuous NLP are added to recorded words and sentences. In contrast, voicing interruptions and pitch jumps dramatically reduce speech intelligibility, likely by interfering with voicing contrasts and normal intonation. We argue that NLP were not eliminated from the human vocal repertoire as we evolved for speech, but only brought under better control.

Human nonverbal vocalizations such as laughter communicate emotion, motivation, and intent during social interactions. While differences between spontaneous and volitional laughs have been described, little is known about the communicative functions of volitional (voluntary) laughter—a complex signal used across diverse social contexts. Here, we examined whether the acoustic structure of volitional laughter encodes social contextual information recognizable by humans and computers. We asked men and women to produce volitional laughs in eight distinct social contexts ranging from positive (e.g., watching a comedy) to negative valence (e.g., embarrassment). Human listeners and machine classification algorithms accurately identified most laughter contexts above chance. However, confusion often arose within valence categories, and could be largely explained by shared acoustics. Although some acoustic features varied across social contexts, including fundamental frequency (perceived as voice pitch) and energy parameters (entropy variance, loudness, spectral centroid, and cepstral peak prominence), which also predicted listeners' recognition of laughter contexts, laughs evoked across different social contexts still often overlapped in acoustic and perceptual space. Thus, we show that volitional laughter can convey some reliable information about social context, but much of this is tied to valence, suggesting that volitional laughter is a graded rather than discrete vocal signal.

In this comparative cross-linguistic study we test whether expressive interjections (words like ouch or yay) share similar vowel signatures across the world's languages, and whether these can be traced back to nonlinguistic vocalizations (like screams and cries) expressing the same emotions of pain, disgust, and joy. We analyze vowels in interjections from dictionaries of 131 languages (over 600 tokens) and compare these with nearly 500 vowels based on formant frequency measures from voice recordings of volitional nonlinguistic vocalizations. We show that across the globe, pain interjections feature a-like vowels and wide falling diphthongs (“ai” as in Ayyy! “aw” as in Ouch!), whereas disgust and joy interjections do not show robust vowel regularities that extend geographically. In nonlinguistic vocalizations, all emotions yield distinct vowel signatures: pain prompts open vowels such as [a], disgust schwa-like central vowels, and joy front vowels such as [i]. Our results show that pain is the only affective experience tested with a clear, robust vowel signature that is preserved between nonlinguistic vocalizations and interjections across languages. These results offer empirical evidence for iconicity in some expressive interjections. We consider potential mechanisms and origins, from evolutionary pressures and sound symbolism to colexification, proposing testable hypotheses for future research.

Human nonverbal vocalizations such as screams and cries often reflect their evolved functions. Although the universality of these putatively primordial vocal signals and their phylogenetic roots in animal calls suggest a strong reflexive foundation, many of the emotional vocalizations that we humans produce are under our voluntary control. This suggests that, like speech, volitional vocalizations may require auditory input to develop typically. Here, we acoustically analyzed hundreds of volitional vocalizations produced by profoundly deaf adults and typically-hearing controls. We show that deaf adults produce unconventional and homogenous vocalizations of aggression and pain that are unusually high-pitched, unarticulated, and with extremely few harsh-sounding nonlinear phenomena compared to controls. In contrast, fear vocalizations of deaf adults are relatively acoustically typical. In four lab experiments involving a range of perception tasks with 444 participants, listeners were less accurate in identifying the intended emotions of vocalizations produced by deaf vocalizers than by controls, perceived their vocalizations as less authentic, and reliably detected deafness. Vocalizations of congenitally deaf adults with zero auditory experience were most atypical, suggesting additive effects of auditory deprivation. Vocal learning in humans may thus be required not only for speech, but also to acquire the full repertoire of volitional non-linguistic vocalizations.

At some point in our evolutionary history, humans lost vocal membranes and air sacs, representing an unexpected simplification of the vocal apparatus relative to other apes. One hypothesis is that these simplifications represent anatomical adaptations for speech because a simpler larynx provides a suitably stable and tonal vocal source with fewer nonlinear vocal phenomena (NLP). The key assumption that NLP reduce speech intelligibility is indirectly supported by studies of dysphonia, but it has not been experimentally tested. Here, we manipulate NLP in vocal stimuli ranging from single vowels to sentences, showing that the source needs to be stable, but not necessarily tonal. When the task is to discriminate synthesized monophthong and diphthong vowels, continuous NLP (subharmonics, amplitude modulation, and even deterministic chaos) actually improve vowel perception in high-pitched voices, likely because the resulting dense spectrum reveals formant transitions. Rough-sounding voices also remain highly intelligible when continuous NLP are added to recorded words and sentences. In contrast, voicing interruptions and pitch jumps dramatically reduce speech intelligibility, likely by interfering with voicing contrasts and normal intonation. We argue that NLP were not eliminated from the human vocal repertoire as we evolved for speech, but only brought under better control.