Who is singing? Voice recognition from spoken versus sung speech.

Singing is socially important but constrains voice acoustics, potentially masking certain aspects of vocal identity. Little is known about how well listeners extract talker details from sung speech or identify talkers across the sung and spoken modalities. Here, listeners (n = 149) were trained to recognize sung or spoken voices and then tested on their identification of these voices in both modalities. Learning vocal identities was initially easier through speech than song. At test, cross-modality voice recognition was above chance, but weaker than within-modality recognition. We conclude that talker information is accessible in sung speech, despite acoustic constraints in song.

Learning to identify talkers: Do 4.5-month-old infants distinguish between unfamiliar males?

Vocal recognition of socially relevant conspecifics is an important skill throughout the animal kingdom. Human infants recognize their own mother at birth, and they distinguish between unfamiliar female talkers by 4.5 months of age. Can 4.5-month-olds also distinguish between unfamiliar male talkers? To date, no adequately powered study has addressed this question. Here, a visual fixation procedure demonstrates that, unlike adults, 4.5-month-olds (N = 48) are worse at telling apart unfamiliar male voices than they are at telling apart unfamiliar female voices. This result holds despite infants' equal attentiveness to unfamiliar male and female voices.

Revisiting the talker recognition advantage in bilingual infants.

Recent work has shown that exposure to multiple languages affects nonlinguistic processing of speech during infancy. Specifically, Fecher and Johnson found that bilingual 9-month-olds outperformed their monolingual peers in a face-voice matching task in an unfamiliar language [Developmental Science (2019a), 22(4), e12778]. What factors were driving this effect? That is, was this finding truly reflective of a bilingual advantage specific to talker processing, or did the study demonstrate a general cognitive advantage in bilingual infants? Here, we revisited this question by testing bilingual and monolingual 9-month-olds (N = 48) on their ability to associate previously unknown voices with animated cartoon characters. In comparison with earlier work, where infants were presented with characters speaking an unfamiliar language (Spanish), the characters in this study spoke a language familiar to both groups of infants (English). Critically, we found that the monolingual and bilingual infants learned the face-voice pairings equally well when they were tested on the familiar language. We conclude that whereas bilingual infants are skilled at recognizing talkers regardless of the language spoken by the talkers, monolingual infants succeed at talker recognition in a familiar language only. These results begin to clarify the underlying nature of the talker recognition benefit previously reported for bilingual infants.

Developmental improvements in talker recognition are specific to the native language.

Previous studies have shown that talker recognition by young children continues to improve into late childhood. But why might this be the case? Are children's gradually improving talker recognition abilities driven primarily by general maturational factors in the cognitive or perceptual domain (general maturation hypothesis), or are these improvements primarily linked to children's increasingly sophisticated linguistic knowledge (language attunement hypothesis)? In the current study, we addressed this question by testing monolingual English-speaking 5- and 6-year-olds (N = 80) on their ability to recognize talkers in a familiar language (i.e., English) and in an unfamiliar language (i.e., Spanish) using a "voice lineup" talker recognition task. We predicted two alternative outcomes. According to the general maturation hypothesis, we should see improvements in talker recognition for both the familiar and unfamiliar languages as children grow older. According to the language attunement hypothesis, however, we should see developmental improvements in talker recognition for the familiar language only. Our findings suggest that early developmental improvements in talker recognition are limited to familiar languages, highlighting the potential central role of language-specific knowledge in talker recognition.

Identifying children's voices.

Human adults rely on both acoustic and linguistic information to identify adult talkers. Assuming favorable conditions, adult listeners recognize other adults fairly accurately and quickly. But how well can adult listeners recognize child talkers, whose speech productions often differ dramatically from adult speech productions? Although adult talker recognition has been heavily studied, only one study to date has directly compared the recognition of unfamiliar adult and child talkers [Creel and Jimenez (2012). J. Exp. Child Psychol. 113(4), 487-509]. Therefore, the current study revisits this question with a much larger and younger sample of child talkers (N = 20); performance with adult talkers (N = 20) was also tested to provide a baseline. In Experiment 1, adults successfully distinguished between adult talkers in an AX discrimination task but performed much worse with child talkers. In Experiment 2, adults were slower and less accurate at learning to identify child talkers than adult talkers in a training-identification task. Finally, in Experiment 3, adults failed to improve at identifying child talkers after three days of training with numerous child voices. Taken together, these findings reveal a sizable difference in adults' ability to recognize child versus adult talkers. Possible explanations and implications for understanding human talker recognition are discussed.

By 4.5 Months, Linguistic Experience Already Affects Infants' Talker Processing Abilities.

Contemporary models of adult speech perception acknowledge that the processing of linguistic and nonlinguistic aspects of the speech signal are interdependent. But when in development does this interdependence first emerge? In the adult literature, one way to demonstrate this relationship has been to examine how language experience affects talker identification. Thus, in this study, 4- to 5-month-old infants (N = 96) were tested on their ability to tell apart talkers in a familiar language (English) compared to unfamiliar languages (Polish or Spanish). Infants readily distinguished between talkers in the familiar language but not in the unfamiliar languages, supporting the hypothesis that the integrated processing of linguistic and nonlinguistic information in speech is early emerging and robust.

Resolving the (Apparent) Talker Recognition Paradox in Developmental Speech Perception.

The infant literature suggests that humans enter the world with impressive built-in talker processing abilities. For example, newborns prefer the sound of their mother's voice over the sound of another woman's voice, and well before their first birthday, infants tune in to language-specific speech cues for distinguishing between unfamiliar talkers. The early childhood literature, however, suggests that preschoolers are unable to learn to identify the voices of two unfamiliar talkers unless these voices are highly distinct from one another, and that adult-level talker recognition does not emerge until children near adolescence. How can we reconcile these apparently paradoxical messages conveyed by the infant and early childhood literatures? Here, we address this question by testing 16.5-month-old infants (N = 80) in three talker recognition experiments. Our results demonstrate that infants at this age have difficulty recognizing unfamiliar talkers, suggesting that talker recognition (associating voices with people) is mastered later in life than talker discrimination (telling voices apart). We conclude that methodological differences across the infant and early childhood literatures-rather than a true developmental discontinuity-account for the performance differences in talker processing between these two age groups. Related findings in other areas of developmental psychology are discussed.

Bilingual infants excel at foreign-language talker recognition.

Bilingual and monolingual infants differ in how they process linguistic aspects of the speech signal. But do they also differ in how they process non-linguistic aspects of speech, such as who is talking? Here, we addressed this question by testing Canadian monolingual and bilingual 9-month-olds on their ability to learn to identify native Spanish-speaking females in a face-voice matching task. Importantly, neither group was familiar with Spanish prior to participating in the study. In line with our predictions, bilinguals succeeded in learning the face-voice pairings, whereas monolinguals did not. We consider multiple explanations for this finding, including the possibility that simultaneous bilingualism enhances perceptual attentiveness to talker-specific speech cues in infancy (even in unfamiliar languages), and that early bilingualism delays perceptual narrowing to language-specific talker recognition cues. This work represents the first evidence that multilingualism in infancy affects the processing of non-linguistic aspects of the speech signal, such as talker identity.

Effects of language experience and task demands on talker recognition by children and adults.

Talker recognition is a language-dependent process, with listeners recognizing talkers better when the talkers speak a familiar versus an unfamiliar language. This language familiarity effect (LFE) is firmly established in adults, but its developmental trajectory in children is not well understood. Some evidence suggests that the effect already exists in infancy, but little is known about how it unfolds in childhood. The present study explored whether the strength of the LFE increases in early childhood. Adults and children were tested in their native language and a foreign language using a "same-different" talker discrimination task and a "voice line-up" talker recognition task. Results showed that adults and 6-year-olds, but not 5-year-olds, exhibit a robust LFE, suggesting that the effect strengthens as children's language competence increases. For both adults and older children, the emergence of an LFE moreover appeared to be task-dependent. This study contributes to a better understanding of how children develop mature talker recognition abilities and when children's processing of indexical and linguistic information in speech approaches adult-like levels. Furthermore, the findings reported here contribute to the debates regarding the origins of the LFE-a hallmark of adult talker recognition.

The native-language benefit for talker identification is robust in 7.5-month-old infants.

Adults recognize talkers better when the talkers speak a familiar language than when they speak an unfamiliar language. This language familiarity effect (LFE) demonstrates the inseparable nature of linguistic and indexical information in adult spoken language processing. Relatively little is known about children's integration of linguistic and indexical information in speech. For example, to date, only one study has explored the LFE in infants. Here, we sought to better understand the maturation of speech processing abilities in infants by replicating this earlier study using a more stringent experimental design (eliminating a potential voice-language confound), a different test population (English- rather than Dutch-learning infants), and a new language pairing (English vs. Polish rather than Dutch vs. Italian or Japanese). Furthermore, we explored the language exposure conditions required for infants to develop an LFE for a formerly unfamiliar language. We hypothesized based on previous studies (including the perceptual narrowing literature) that infants might develop an LFE more readily than would adults. Although our findings replicate those of the earlier study-demonstrating that the LFE is robust in 7.5-month-olds-we found no evidence that infants need less language exposure than do adults to develop an LFE. We concluded that both infants and adults need extensive (potentially live) exposure to an unfamiliar language before talker identification in that language improves. Moreover, our study suggests that the LFE is likely rooted in early emerging phonology rather than shared lexical knowledge and that infants already closely resemble adults in their processing of linguistic and indexical information. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Toddlers' comprehension of adult and child talkers: Adult targets versus vocal tract similarity.

How do children represent words? If lexical representations are based on encoding the indexical characteristics of frequently-heard speakers, this predicts that speakers like a child's own mother should be best understood. Alternatively, if they are based on the child's own motor productions, this predicts an own-voice advantage in word recognition. Here, we address this question by presenting 2.5-year-olds with recordings of their own voice, another child's voice, their own mother's voice, and another mother's voice in a child-friendly eye-tracking procedure. No own-voice or own-mother advantage was observed. Rather, children uniformly performed better on adult voices than child voices, even performing better for unfamiliar adult voices than own voices. We conclude that children represent words not in the form of own-voice motor codes or frequently heard speakers, but on the basis of adult speech targets.

Two-year-olds' sensitivity to subphonemic mismatch during online spoken word recognition.

Sensitivity to noncontrastive subphonemic detail plays an important role in adult speech processing, but little is known about children's use of this information during online word recognition. In two eye-tracking experiments, we investigate 2-year-olds' sensitivity to a specific type of subphonemic detail: coarticulatory mismatch. In Experiment 1, toddlers viewed images of familiar objects (e.g., a boat and a book) while hearing labels containing appropriate or inappropriate coarticulation. Inappropriate coarticulation was created by cross-splicing the coda of the target word onto the onset of another word that shared the same onset and nucleus (e.g., to create boat, the final consonant of boat was cross-spliced onto the initial CV of bone). We tested 24-month-olds and 29-month-olds in this paradigm. Both age groups behaved similarly, readily detecting the inappropriate coarticulation (i.e., showing better recognition of identity-spliced than cross-spliced items). In Experiment 2, we asked how children's sensitivity to subphonemic mismatch compared to their sensitivity to phonemic mismatch. Twenty-nine-month-olds were presented with targets that contained either a phonemic (e.g., the final consonant of boat was spliced onto the initial CV of bait) or a subphonemic mismatch (e.g., the final consonant of boat was spliced onto the initial CV of bone). Here, the subphonemic (coarticulatory) mismatch was not nearly as disruptive to children's word recognition as a phonemic mismatch. Taken together, our findings support the view that 2-year-olds, like adults, use subphonemic information to optimize online word recognition.