The human voice is a common and important part of the social environment. In addition to being the primary carrier of language, there is growing evidence that the sound of a person’s voice contains a great deal of socially relevant information. Drawing on a functional approach to perception, the current research investigated the attunement of social perceivers to the vocal specification of speaker physical properties. An initial study developed a set of vocal samples for use in subsequent perceptual studies, and conducted exploratory analyses investigating relationships between speaker vocal and physical characteristics. Significant differences in the acoustic properties of male and female voices were identified, but the relationships between acoustic properties and speaker age, body size, and body configuration were less robust. Study 2 investigated the ability of listeners to accurately perceive the physical characteristics of speakers from vocal information. Perceivers made assessments of speaker physical characteristics that were highly consensual and that accurately reflected speaker sex, age, and body size. Studies 3 and 4 investigated perceiver judgments of vocal attractiveness. In Study 3, both male and female perceivers rated the voices of male speakers with lower indices of body asymmetry (a marker of genotypic and phenotypic condition) as more attractive. However, for female perceivers it was shown that this relationship is influenced by changes in fertility levels associated with the menstrual cycle. At times of high fertility female perceivers displayed a stronger attraction to the voices of male speakers with low asymmetry than they did at times of low fertility. This finding was interpreted as a functional shift increasing attraction to males possessing phenotypic markers of high fitness when the likelihood of conception is highest. Study 4 considered the effects of menstrual cycle variation on the voices of female speakers. Both male and female perceivers rated female voices recorded during a phase of high fertility to be more attractive than the same voices recorded during a phase of low fertility. This finding extends previous research demonstrating cyclic shifts in visual and olfactory attractiveness to the auditory domain, and is discussed in terms of the vocal specificity of female fertility status. Study 5 extended the previous studies by considering how vocal cues specifying the sex and age of a social target interact with visual cues to influence social perception. Relative to concordant voice and face information, discordant information was found to facilitate social memory. This finding is discussed with regards to the integration of multiple sources of information in social perception. The results of all studies are discussed in terms of the adaptive significance of perceivers accurately detecting the physical characteristics of others that are specified vocally.

Adult listeners more accurately identify talkers speaking a known language than a foreign language (Thompson, 1987), a phenomenon known as the language-familiarity effect (Perrachione & Wong, 2007). Two experiments explored how knowledge of a language facilitates talker identification. In Experiment 1, participants identified talkers in three conditions: (a) a foreign-language speech condition featuring unfamiliar sound patterns and no known words; (b) a nonsense speech condition featuring all the familiar sound patterns of their native language, such as familiar phonemes, prosody, and syllable structure, but no actual words; and (c) a native-language condition with all the familiar components of a language, including words. In Experiment 2, participants again identified speakers in familiar and unfamiliar languages. In both languages, listeners identified speakers in a condition in which no word was ever repeated, and in a condition featuring repeated words. The results suggest that access to familiar, meaningful spoken words confers an advantage beyond access to familiar sounds, syllables, and prosody, particularly when words are repeated. Together, Experiments 1 and 2 support integrated models of voice and language processing systems, and indicate that access to meaningful words is a crucial component of the language-familiarity effect in talker identification.

Un nombre croissant d'études révèle combien les processus cérébraux de production et de perception de l'action sont intriqués. En particulier, on sait maintenant que la perception de la parole induit l'activation de représentations motrices articulatoires chez l'auditeur. Dans ce travail, nous explorons la perception de la voix chantée, une action vocale non-linguistique. L'écoute d'une voix chantée provoque-t-elle une activation du système moteur ? Cette activité motrice est-elle plus forte pour la voix que pour un son musical non-biologique ? Ces questions sont abordées en utilisant de façon complémentaire deux protocoles comportementaux, une technique de lésion virtuelle par stimulation magnétique transcrâniale, l'étude des oscillations en EEG et celle de la variabilité métabolique en IRMf. Nos résultats montrent que la perception d'une voix chantée est effectivement associée à une activité du cortex sensorimoteur dans des tâches de répétition et de discrimination. De façon intéressante, les plus mauvais chanteurs ont montré la plus forte résonance motrice. Le système moteur pourrait, par la génération de modèles internes, faciliter le traitement des stimuli ou la préparation de la réponse vocale quand le traitement acoustique seul est insuffisant. L'ensemble des résultats présentés ici suggère que les interactions audiomotrices en perception de la voix humaine sont modulées par la dimension biologique du son et par le niveau d'expertise vocale des auditeurs. / A growing body of research reveals that action production and action perception interact. In particular, it has been shown that speech perception entails articulatory motor representations in the listener. In the present work, we investigate the perception of a singing voice, a stimulus that is not primarily linked to articulatory processes. Does listening to a singing voice induce activity in the motor system? Is this motor activity stronger for a voice than for a non-biological musical sound? Two behavioral tasks, a og virtual lesionfg{} paradigm using TMS, the study of brain oscillations with EEG and an fMRI experiment carried out during my PhD have shed some light on these questions. Our results show that the perception of a singing voice is indeed associated with sensorimotor activity in repetition and discrimination tasks. Interestingly, the poorer singers displayed the stronger motor resonance. The motor system could facilitate the processing of sound or the preparation of the vocal response by internal model generation when the acoustic processing is not effective enough. The set of studies presented here thus suggests that audiomotor interactions in human voice perception are modulated by two factors: the biological dimension of sound and the listeners' vocal expertise. These results suggest new perspectives on our understanding of the auditory-vocal loop in speech and of sound perception in general.

Chez l'homme, la voix facilite les interactions sociales par la transmission d’informations sur l'identité de la personne, ses émotions ou sa personnalité. En particulier, l'identité du locuteur peut être automatiquement extraite même lorsque le message et l'état émotionnel varient, ce qui suggère des mécanismes cognitifs et cérébraux partiellement dissociables pour ces processus. Cependant, la reconnaissance d'une voix familière ou la discrimination entre deux locuteurs sont, pour certains sujets, non seulement non-automatiques, mais même impossibles. Ce déficit, lorsqu'il se manifeste dès la naissance, est appelé phonagnosie du développement et constitue la contrepartie auditive de la prosopagnosie (déficit de reconnaissance des visages). Dans le domaine visuel, il a été proposé que les sujets affectés par la prosopagnosie du développement représentent des cas extrêmes dans la distribution des capacités de reconnaissance de visages. A l’inverse, des "super-reconnaisseurs" des visages se situaient à l’opposé de cette distribution.Comme la distribution des capacités de reconnaissance de la voix dans la population générale était encore inconnue, le premier objectif de cette thèse a été d'en étudier les différences individuelles au moyen d'un court test - le Glasgow Voice Memory Test (GVMT). Les résultats obtenus ont reflété une large variabilité interindividuelle dans les capacités de reconnaissance des voix: parmi une cohorte de 1120 sujets, il y avait à la fois des sujets avec des performances significativement en dessous de la moyenne (potentiels phonagnosiques) et des "super-reconnaisseurs" des voix. Cette variabilité individuelle comportementale semblerait se refléter au niveau cérébral, comme révélés par l'imagerie par résonance magnétique fonctionnelle (IRMf) : en fait, il a été montré précédemment qu'il existait une variabilité interindividuelle considérable dans le signal BOLD (blood-oxygen level dependent) lié à la voix dans les zones temporales de la voix (TVAs). Ces régions sont situées sur le bord supérieur des sulcus/gyrus temporal supérieur (STS/STG) et montrent une activation préférentielle pour les sons vocaux plutôt que non vocaux. Le deuxième objectif de ce travail fut de mieux caractériser le lien entre les mécanismes comportementaux et neuronaux sous-tendant la variabilité interindividuelle dans les processus de reconnaissance des voix. Pour cela, nous avons examiné comment la perception de la voix modulait la connectivité fonctionnelle entre les TVAs, constituant le "noyau" du réseau de perception de la voix, et les régions frontales également sensibles aux voix, constituant une extension de ce réseau. Les résultats ont montré qu'il y avait une connectivité fonctionnelle positive dans l'ensemble du réseau et que la connectivité fonctionnelle fronto-temporelle et fronto-frontale droite augmentait avec les scores obtenus lors du GVMT.Pour compléter ce travail, nous avons réalisé une autre étude IRMf en utilisant des analyses multivariées, afin de clarifier les corrélats neuronaux de la reconnaissance du locuteur mais aussi le lien entre sensibilité cérébrale à la voix et capacités de reconnaissance du locuteur. Pour cela, des sujets ayant des capacités de reconnaissance vocale hétérogènes ont été soumis à la fois à une tâche d'identification du locuteur et à une tâche d'écoute passive de sons vocaux et non vocaux. Les résultats ont confirmé que l’identification du locuteur s’effectuait via un réseau étendu de régions, incluant les TVAs mais aussi des régions frontales. De plus, nous avons observé que le score de classification voix/non-voix dans le STS droit permettait de prédire les capacités d'identification des locuteurs.Dans l'ensemble, ces résultats suggèrent que les capacités de reconnaissance vocale varient considérablement d'un individu à l'autre et que cette variabilité pourrait être le reflet de profils d’activité cérébrale différents au sein du réseau de la perception de la voix. / In humans, voice conveys heterogeneous information such as speaker’s identity, which can be automatically extracted even when language content and emotional state vary. We hypothesized that the ability to recognize a speaker considerably varied across the population, as previously observed for face recognition. To test this hypothesis, a short voice recognition test was delivered to 1120 subjects in order to observe how voice recognition abilities were distributed in the general population. Since it has been previously observed that there exists a considerable inter-individual variability in voice-elicited activity in temporal voice areas (TVAs), regions along the superior temporal sulcus/gyrus (STS/STG) that show preferentially activation for voices than other sounds, the second aim of this work was then to better characterize the link between the behavioral and neural mechanisms underlying inter-individual variability in voice recognition processes through functional magnetic resonance imaging (fMRI). The results of a first fMRI study showed that functional connectivity between frontal and temporal voice sensitive regions increased with voice recognition scores obtained at a voice recognition test. Another fMRI study showed that speaker’s identity was treated in an extended network of regions, including TVAs but also frontal regions and that voice/non-voice classification accuracy in right STS increased with speaker identification abilities. Altogether, these results suggest that voice recognition abilities considerably vary across subjects and that this variability can be mirrored by different neural profiles within the voice perception network.

Perceptual speech and voice analysis is an essential skill for all speech-language pathologists, but it is a difficult skill to teach. Even the reliability for experienced experts is variable. Some training literature and practices in speech-language pathology suggest that imitating pathological voices may be useful for developing perceptual judgment. Evidence from other fields suggests that motor experience influences perception. Until now the link between production and perception of voice quality has not been addressed. The purpose of this pilot study is to test the hypothesis that imitating pathological voice samples would improve the perceptual discrimination abilities of naïve, inexperienced listeners. Three expert listeners rated 25 voice samples using a perceptual voice evaluation scale, the Grade, Instability, Roughness, Breathiness, Asthenia, Strain Scale (GIRBAS) (Dejonckere et al., 1996), and identified anchor samples for the training protocol. These expert ratings were used to develop summary expert ratings that served as a comparison for the naïve listener ratings. Two groups of naïve undergraduate listeners received training in evaluating voice quality and in administering the GIRBAS. They completed a pretest, a training session, a homework session, and a post-test. During each activity, they rated 6 voices and provided a confidence rating for their scores. The experimental group imitated the voice samples during the study, and the control group completed the training without supplemental motor experience. It was hypothesized that both listener groups would have improved accuracy and confidence levels between the pretest and post-test, with a larger improvement for the experimental group. Data suggested that training improved naïve listener accuracy and confidence levels and that this improvement was maintained for at least seven days after the initial training. Post-test accuracy for both groups was approximately the same. Imitation did not improve the accuracy of ratings, although those subjects had higher confidence levels. The data supported previous research that found that training improved the accuracy of perceptual voice evaluations. However, the hypothesis that imitation could improve perceptual ratings was not supported by this study and bears further investigation due to the small sample size.

Tal och röst styrs av komplicerade processer, där vitt skilda funktioner används i dess produktion och perception. Hur tal och röst uppfattas skiljer sig på flera sätt från den objektiva mätbara akustiska talsignalen. Grundtonens, F0’s, styrka och det man kallar talarformanten är två parametrar som påverkar hur rösten låter. Studien hade som syfte att undersöka om grundtonens styrka och med eller utan talarformant påverkar vilka stimuli otränade röstbedömare tycker bäst om. För att undersöka detta skapades ett syntetiskt /a/ efter formantfrekvenser för svenska vokaler (Fant, 1959), som varierades med utan eller med talarformant och med sju olika grundtonsstyrkor, totalt fjorton stimuli. Tolv kvinnor och åtta män, fick lyssna på /a/:na och skatta dem från det /a/ som de gillade mest till det /a/ som de gillade minst. Studiens frågeställningar bekräftades, variationer av grundtonens styrka och med eller utan talarformant påverkade vilka stimuli otränade röstbedömare föredrog, och män och kvinnor föredrog olika stimuli. De två /a/:na med svagast och det /a/ med starkast grundton, gillades minst av hela gruppen. De fyra /a/:na däremellan tyckte informanterna om ungefär lika mycket. Studerade man var för sig vad män och kvinnor skattade blev resultatet annorlunda. Kvinnor föredrog stimuli med talarformant mer än de utan talarformant, medan män föredrog stimuli med stark grundton. Ytterligare studier kunde vara intressanta att göra, för att undersöka om stimulus egenskaper med avseende på talarformant och grundtonsstyrka har någon effekt på hur tal uppfattas och tolkas. / Speech and voice is governed by complicated processes, where a variety of different functions are used in its production and perception. Speech and voice differs in many ways from the objective measurable acoustic speech signal. The intensity of the fundamental frequency, F0, and what is called the speaker formant are two parameters that affect how voice is perceived. The purpose of the study was to investigate if the varied intensity of F0 and with or without speaker formant affect what stimuli untrained voice assessors like the most. To do so, a synthetic /a/ was created, formed by formant frequencies for Swedish vowels (Fant, 1959), varied with with or without speaker formant, and seven different intensities of the fundamental frequency, creating a total of 14 stimuli. Twelve women and eight men were asked to listen to and grade the stimuli, from the /a/ that was liked the most to the one that was liked the least. The expectations of the study were confirmed, the variation of the intensity of F0 and with or without speaker formant, did affect which stimuli the listeners preferred, and also confirmed that men and women preferred different stimuli. The two /a/’s with the weakest and the /a/ with the strongest intensity of F0, were least liked. The four /a/s with varying intensity of F0 in between, were liked approximately the same. If men and women ratings were studied separately from one another, the result differed. Women preferred stimuli with speaker formant more than the ones without, whereas men more appreciated stimuli with strong intensity of F0. If the study was the be retested and the results would be confirmed, further tests would be of interest to do, to investigate if the differences of preferences affect how speech is perceived and interpreted.

Kommunikation ist allgegenwärtig in unserem Alltag. Personen mit einer Autismus-Spektrum-Störung (ASS) zeigen soziale Schwierigkeiten und beim Erkennen von Kommunikationssignalen von Gesicht und Stimme. Da derartige Schwierigkeiten die Lebensqualität beeinträchtigen können, ist ein tiefgreifendes Verständnis der zugrundeliegenden Mechanismen von großer Bedeutung. In der vorliegenden Dissertation befasste ich mich mit sensorischen Gehirnmechanismen, die der Verarbeitung von Kommunikationssignalen zugrunde liegen und, die in der Forschung zu ASS bisher wenig Beachtung fanden. Erstens untersuchte ich, ob eine intranasale Gabe von Oxytocin die Erkennung der Stimmenidentität beeinflussen, und ihre Auffälligkeiten bei Personen mit ASS mildern kann. Zweitens erforschte ich, welche neuronalen Prozesse den Schwierigkeiten in der Wahrnehmung visueller Sprache in ASS zugrunde liegen, da bisherige Evidenz nur auf Verhaltensdaten basierte. Diese Fragestellungen beantwortete ich mit Hilfe von funktioneller Magnetresonanztomographie, Eyetracking und Verhaltenstestungen. Die Ergebnisse der Dissertation liefern neuartige Erkenntnisse, die für Personen mit ASS und typisch entwickelte Personen von hoher Relevanz sind. Erstens bestätigen sie die Annahmen, dass atypische sensorische Mechanismen für unser Verständnis der sozialen Schwierigkeiten in ASS grundlegend sind. Sie zeigen, dass atypische Funktionen sensorischer Gehirnregionen den Kommunikationseinschränkungen in ASS zugrunde liegen und die Effektivität von Interventionen beeinflussen, die jene Schwierigkeiten vermindern sollen. Zweitens liefern die Ergebnisse empirische Evidenz für theoretische Annahmen darüber, wie das typisch entwickelte Gehirn visuelle Kommunikationssignale verarbeitet. Diese Erkenntnisse erweitern maßgeblich unser aktuelles Wissen und zukünftige Forschungsansätze zur zwischenmenschlichen Kommunikation. Außerdem können sie neue Interventionsansätze zur Förderung von Kommunikationsfähigkeiten hervorbringen. / Communication is ubiquitous in our everyday life. Yet, individuals with autism spectrum disorder (ASD) have difficulties in social interactions and to recognize socially relevant signals from the face and the voice. Such impairments can vastly affect the quality of life - a profound understanding of the mechanisms behind these difficulties is thus strongly required. In the current dissertation, I focused on sensory brain mechanisms that underlie the perception of emotionally neutral communication signals that so far have gained little attention in ASD research. I studied the malleability of voice-identity processing using intranasal administration of oxytocin, and thus the potential to alleviate voice-identity recognition impairments in ASD. Furthermore, I investigated brain mechanisms that underlie recognition difficulties for visual speech in ASD, as until now evidence on visual-speech recognition in ASD was limited to behavioral findings. I applied methods of functional magnetic resonance imaging, eye tracking, and behavioral testing. The contribution of the present dissertation is twofold. First, the findings corroborate the view that atypical sensory perception is a critical cornerstone for understanding of social difficulties in ASD. Dysfunction of visual and auditory sensory brain regions might contribute to difficulties in processing aspects of communication signals in ASD and modulate the efficacy of interventions for improving the behavioral deficits. Second, the findings deliver empirical support for a recent theoretical model of how the typically developing brain perceives dynamic faces. This improved our current knowledge about brain processing of visual communication signals in the typically developing population. Advanced scientific knowledge about human communication, as provided in the current dissertation, propels further empirical research and development of clinical interventions that aim to promote communication abilities in affected individuals.

The human voice may convey meaningful information about socially and evolutionarily relevant characteristics of the vocalizer. In turn, listeners may readily evaluate personal characteristics, such as body size, on the basis of nonverbal voice features. Research investigating vocal communication of physical size in humans has focused on two salient and largely independent voice features, fundamental frequency and/or corresponding harmonics (perceived as voice pitch) and formant frequencies (resonance frequencies of the supralaryngeal vocal tract). However, the degree to which fundamental and formant frequencies reliably predict variation in body size controlling for sex and age, and their relative role in the perception or accurate estimation of body size, has to date been unclear. In the current thesis, using meta-analysis, I establish that formants reliably predict variation in men’s and women’s heights and weights. In contrast, fundamental frequency only weakly predicts men’s heights and women’s weights. These findings corroborate work on many other mammals whose vocal production, like humans, follows the source-filter model. Despite the lack of a robust physical relationship between fundamental frequency and size within sexes, I further demonstrate that listeners utilize voice pitch to accurately gauge men’s relative height. My research suggests that voice pitch indirectly facilitates accurate size assessment by providing a carrier signal (i.e., dense harmonics) for formants. This is the first evidence that pitch does not confound accurate size estimation. Finally, I demonstrate that voices with lowered pitch, but not raised pitch, are perceived as larger when projected from a low than high spatial location. These results suggest that strong cross-modal perceptual biases linking low pitch to low elevation and large size may, in some contexts, cause errors in size estimation. Taken together, this thesis provides a detailed account of human vocal communication of body size, which can play a meaningful role in sexual and social contexts. / Dissertation / Doctor of Philosophy (PhD)