Prosody in Infant-Directed Speech Is Similar Across Western and Traditional Cultures

When speaking to infants, adults typically alter the acoustic properties of their speech in a variety of ways compared with how they speak to other adults; for example, they use higher pitch, increased pitch range, more pitch variability, and slower speech rate. Research shows that these vocal changes happen similarly across industrialized populations, but no studies have carefully examined basic acoustic properties of infant-directed (ID) speech in traditional societies. Moreover, some scholars have suggested that ID speech is culturally specific and does not exist in some small-scale societies. We examined fundamental frequency (F₀) production and speech rate in mothers speaking to both infants and adults in three cultures: Fijians, Kenyans, and North Americans. In all three cultures, speakers used higher F₀ when speaking to infants relative to when speaking to other adults, and they also used significantly greater F₀ variation and fewer syllables per second. Previous research has found that American mothers tend to use higher pitch than do mothers from other cultures, but when maternal education was controlled in the current study, we did not find a significant difference in average pitch across our three populations. This is the first research systematically comparing spontaneous ID and adult-directed speech prosody between Western and traditional societies, and it is consistent with a large body of evidence showing similar acoustic patterns in ID speech across industrialized populations.     

Pitch characteristics of infant-directed speech affect infants’ ability to discriminate vowels

“Baby talk” or speech directed to prelinguistic infants is high in pitch and has exaggerated pitch contours (up/down patterns of pitch change) across languages and cultures. Using an acoustic model, we predicted that the large pitch contours of infant-directed speech should improve infants’ ability to discriminate vowels. On the other hand, the same model predicted that high pitch would not benefit, and might actually impair, infants’ ability to discriminate vowels. We then confirmed these predictions experimentally. We conclude that the exaggerated pitch contours of infant-directed speech aid infants’ acquisition of vowel categories but that the high pitch of infant-directed speech must serve another function, such as attracting infants’ attention or aiding emotional communication.     

Musical ability and non‐native speech‐sound processing are linked through sensitivity to pitch and spectral information

Is the observed link between musical ability and non‐native speech‐sound processing due to enhanced sensitivity to acoustic features underlying both musical and linguistic processing? To address this question, native English speakers (N = 118) discriminated Norwegian tonal contrasts and Norwegian vowels. Short tones differing in temporal, pitch, and spectral characteristics were used to measure sensitivity to the various acoustic features implicated in musical and speech processing. Musical ability was measured using Gordon's Advanced Measures of Musical Audiation. Results showed that sensitivity to specific acoustic features played a role in non‐native speech‐sound processing: Controlling for non‐verbal intelligence, prior foreign language‐learning experience, and sex, sensitivity to pitch and spectral information partially mediated the link between musical ability and discrimination of non‐native vowels and lexical tones. The findings suggest that while sensitivity to certain acoustic features partially mediates the relationship between musical ability and non‐native speech‐sound processing, complex tests of musical ability also tap into other shared mechanisms.     

Is infant-directed speech prosody a result of the vocal expression of emotion?

Many studies have found that infant-directed (ID) speech has higher pitch, has more exaggerated pitch contours, has a larger pitch range, has a slower tempo, and is more rhythmic than typical adult-directed (AD) speech. We show that the ID speech style reflects free vocal expression of emotion to infants, in comparison with more inhibited expression of emotion in typical AD speech. When AD speech does express emotion, the same acoustic features are used as in ID speech. We recorded ID and AD samples of speech expressing love-comfort, fear, and surprise. The emotions were equally discriminable in the ID and AD samples. Acoustic analyses showed few differences between the ID and AD samples, but robust differences across the emotions. We conclude that ID prosody itself is not special. What is special is the widespread expression of emotion to infants in comparison with the more inhibited expression of emotion in typical adult interactions.     

The relationship between language production and verbal short-term memory: The role of stress grouping

This study investigates the influence of stress grouping on verbal short-term memory (STM). English speakers show a preference to combine syllables into trochaic groups, both lexically and in continuous speech. In two serial recall experiments, auditory lists of nonsense syllables were presented with either trochaic (STRONG–weak) or iambic (weak–STRONG) stress patterns, or in monotone. The acoustic correlates that carry stress were also manipulated in order to examine the relationship between input and output processes during recall. In Experiment 1, stressed and unstressed syllables differed in intensity and pitch but were matched for spoken duration. Significantly more syllables were recalled in the trochaic stress pattern condition than in the iambic and monotone conditions, which did not differ. In Experiment 2, spoken duration and pitch were manipulated but intensity was held constant. No effects of stress grouping were observed, suggesting that intensity is a critical acoustic factor for trochaic grouping. Acoustic analyses demonstrated that speech output was not identical to the auditory input, but that participants generated correct stress patterns by manipulating acoustic correlates in the same way in both experiments. These data challenge the idea of a language-independent STM store and support the notion of separable phonological input and output processes.     

Slow Speech Enhances Younger But Not Older Infants' Perception of Vocal Emotion

Infants attend more to infant-directed speech (IDS) than to adult-directed speech (ADS), but infants also prefer speech judged to be high in positive emotion over less emotional speech regardless of whether it is IDS or ADS. Emotion in voices is often conveyed by absolute pitch, pitch contours, and tempo (or duration). The purpose of our study was to explore how perceived emotion in speech is enhanced or attenuated by duration. We tested 18- and 32-week-old infants for attention to IDS that was either high or low in emotion (as judged by adults) and at two different durations (normal vs. slow). The results showed that 18-week-olds attended more to slow IDS (with affect constant), attended more to high affect (with duration constant), and showed equal attention when affect and duration were juxtaposed. In contrast, 32-week-olds showed greater attention to normal IDS regardless of its emotional level. Slower IDS may enhance younger infants' perception of vocal emotion but does not increase attention in older infants perhaps because they no longer rely on this acoustic cue for emotion. We suggest future studies to help tease apart these interpretations.     

音高和时长信息感知的范畴特异性及其发展

通过考察不同范畴间相同声音特征和同一范畴内不同声音特征的感知探讨了言语和音乐中音高和时长信息感知的特异性及发展模式。结果发现：同一范畴内不同声音特征的感知显著相关,支持音高和时长信息加工的范畴特异性理论;高一学生只在言语中的音高和时长信息的感知上具有明显的范畴特异性,说明范畴特异性的形成因声音范畴属性的不同而有所差异;高一学生言语中音高信息的感知能力好于对时长信息的感知,而成人却没有差异,可能是受到了母语和第二语言学习经验的影响。     

The attention-getting capacity of whines and child-directed speech

The current study tested the ability of whines and child-directed speech to attract the attention of listeners involved in a story repetition task. Twenty non-parents and 17 parents were presented with two dull stories, each playing to a separate ear, and asked to repeat one of the stories verbatim. The story that participants were instructed to ignore was interrupted occasionally with the reader whining and using child-directed speech. While repeating the passage, participants were monitored for Galvanic skin response, heart rate, and blood pressure. Based on 4 measures, participants tuned in more to whining, and to a lesser extent child-directed speech, than neutral speech segments that served as a control. Participants, regardless of gender or parental status, made more mistakes when presented with the whine or child-directed speech, they recalled hearing those vocalizations, they recognized more words from the whining segment than the neutral control segment, and they exhibited higher Galvanic skin response during the presence of whines and child- directed speech than neutral speech segments. Whines and child-directed speech appear to be integral members of a suite of vocalizations designed to get the attention of attachment partners by playing to an auditory sensitivity among humans. Whines in particular may serve the function of eliciting care at a time when caregivers switch from primarily mothers to greater care from other caregivers.     

Acoustic determinants of infant preference for motherese speech

Three experiments investigated possible acoustic determinants of the infant listening preference for motherese speech found by Fernald 1985. To test the hypothesis that the intonation of motherese speech was sufficient to elicit this preference, it was necessary to eliminate lexical content and to isolate the three major acoustic correlates of intonation: (1) fundamental frequency (F_o), or pitch; (2) amplitude, correlated with loudness; and (3) duration, related to speech rhythm. Three sets of auditory reinforcers were computer-synthesized, derived from the F_o (Experiment 1), amplitude (Experiment 2), and duration (Experiment 3) characteristics of the infant- and adult-directed natural speech samples used by Fernald 1985. Thus, each of these experiments focused on particular prosodic variables in the absence of segmental variation. Twenty 4-month-old infants were tested in an operant auditory preference procedure in each experiment. Infants showed a significant preference for the F_o-patterns of motherese speech, but not for the amplitude or duration patterns of motherese.     

Does he sound cooperative? Acoustic correlates of cooperativeness

The sound of the voice has several acoustic features that influence the perception of how cooperative the speaker is. It remains unknown, however, whether these acoustic features are associated with actual cooperative behaviour. This issue is crucial to disentangle whether inferences of traits from voices are based on stereotypes, or facilitate the detection of cooperative partners. The latter is likely due to the pleiotropic effect that testosterone has on both cooperative behaviours and acoustic features. In the present study, we quantified the cooperativeness of native French-speaking men in a one-shot public good game. We also measured mean fundamental frequency, pitch variations, roughness, and breathiness from spontaneous speech recordings of the same men and collected saliva samples to measure their testosterone levels. Our results showed that men with lower-pitched voices and greater pitch variations were more cooperative. However, testosterone did not influence cooperative behaviours or acoustic features. Our finding provides the first evidence of the acoustic correlates of cooperative behaviour. When considered in combination with the literature on the detection of cooperativeness from faces, the results imply that assessment of cooperative behaviour would be improved by simultaneous consideration of visual and auditory cues.     

Acoustic analysis of lexical tone in Mandarin infant-directed speech

Using Mandarin Chinese, a "tone language" in which the pitch contours of syllables differentiate words, the authors examined the acoustic modifications of infant-directed speech (IDS) at the syllable level to test 2 hypotheses: (a) the overall increase in pitch and intonation contour that occurs in IDS at the phrase level would not distort lexical pitch at the syllable level and (b) IDS provides exaggerates cues to lexical tones. Sixteen Mandarin-speaking mothers were recorded while addressing their infants and addressing an adult. The results indicate that IDS does not distort the acoustic cues that are essential to word meaning at the syllable level; evidence of exaggeration of the acoustic differences in IDS was observed, extending previous findings of phonetic exaggeration to the lexical level.     

The effect of vowel similarity and syllable length on acoustic memory

Darwin and Baddeley (1974) argue that the presence of recency, suffix, and modality effects are not attributable to the acoustic properties of the stimuli but, rather, to the acoustic distance between the items comprising the test series. The present study is designed to determine whether stimulus duration is a significant variable in acoustic memory. Eight different blocks of synthetic stimuli were prepared; one block each of 60 msec similar and dissimilar syllables and 190 msec similar and dissimilar syllables. The other four blocks consisted of these same vocabularies, but each list in the block had an eighth syllable suffix of the same duration as the syllables in the block. Significant recency and suffix effects are seen for dissimilar syllables of both durations. No effects are demonstrated for 60-msec similar syllables, but both of the effects are seen for 190-msec similar syllables. These results indicate that whether or not a speech sound is preserved in precategorical acoustic storage (PAS) depends upon not only the acoustic distance between the stimuli, but also on other characteristics intrinsic to the stimuli, e.g., stimulus duration.     

Enhanced music sensitivity in 9-month-old bilingual infants

This study explores the influence of bilingualism on the cognitive processing of language and music. Specifically, we investigate how infants learning a non-tone language perceive linguistic and musical pitch and how bilingualism affects cross-domain pitch perception. Dutch monolingual and bilingual infants of 8–9 months participated in the study. All infants had Dutch as one of the first languages. The other first languages, varying among bilingual families, were not tone or pitch accent languages. In two experiments, infants were tested on the discrimination of a lexical (N = 42) or a violin (N = 48) pitch contrast via a visual habituation paradigm. The two contrasts shared identical pitch contours but differed in timbre. Non-tone language learning infants did not discriminate the lexical contrast regardless of their ambient language environment. When perceiving the violin contrast, bilingual but not monolingual infants demonstrated robust discrimination. We attribute bilingual infants’ heightened sensitivity in the musical domain to the enhanced acoustic sensitivity stemming from a bilingual environment. The distinct perceptual patterns between language and music and the influence of acoustic salience on perception suggest processing diversion and association in the first year of life. Results indicate that the perception of music may entail both shared neural network with language processing, and unique neural network that is distinct from other cognitive functions.     

弱智儿童自发性话语中的情感韵律研究

本文用提取声学参数的方法,采用故事讲述任务对弱智儿童自发性话语中的情感韵律进行研究。通过与两组典型儿童-实际年龄匹配组和语言能力匹配组进行比较,探究了弱智儿童自发性话语中情感韵律的表达情况。结果发现：（1）弱智儿童的情感韵律存在一定程度的损伤,在音高范围和元音时长上均有表现;（2）弱智儿童的情感韵律独立于词汇和句法,具有模块性。     

Perception of acoustic correlates of major phrasal units by young infants.

How might young learners parse speech into linguistically relevant units? Sensitivity to prosodic markers of these segments is one possibility. Seven experiments examined infants' sensitivity to acoustic correlates of phrasal units in English. The results suggest that: (a) 9 month olds, but not 6 month olds, are attuned to cues that differentially mark speech that is artificially segmented at linguistically COINCIDENT as opposed to NONCOINCIDENT boundaries (Experiments 1 and 2); (b) the pattern holds across both subject phrases and predicate phrases and across samples of both Child- and Adult-directed speech (Experiments 3, 4, and 7); and (c) both 9 month olds and adults show the sensitivity even when most phonetic information is removed by low-pass filtering (Experiments 5 and (6). Acoustic analyses suggest that pitch changes and in some cases durational changes are potential cues that infants might be using to make their discriminations. These findings are discussed with respect to their implications for theories of language acquisition.     

Do temporal processes underlie left hemisphere dominance in speech perception?

It is not unusual to find it stated as a fact that the left hemisphere is specialized for the processing of rapid, or temporal aspects of sound, and that the dominance of the left hemisphere in the perception of speech can be a consequence of this specialization. In this review we explore the history of this claim and assess the weight of this assumption. We will demonstrate that instead of a supposed sensitivity of the left temporal lobe for the acoustic properties of speech, it is the right temporal lobe which shows a marked preference for certain properties of sounds, for example longer durations, or variations in pitch. We finish by outlining some alternative factors that contribute to the left lateralization of speech perception.     

音高模式加工的大脑偏侧化研究

作为一种超音段成分,音高在言语的理解和产生过程中承担着重要作用,这些作用主要包括:区别不同声调的词汇意义,区别陈述、疑问等不同的语调,标志话语的情绪色彩等。音段、语义和句法信息的加工具有左脑优势,但音高模式加工的单侧优势及其机制还存在很多争论,本文从音高模式加工的两个主要理论———功能假设和声音信号假设出发,对相关研究加以评述。     

Are Words Easier to Learn From Infant‐ Than Adult‐Directed Speech? A Quantitative Corpus‐Based Investigation

We investigate whether infant‐directed speech (IDS) could facilitate word form learning when compared to adult‐directed speech (ADS). To study this, we examine the distribution of word forms at two levels, acoustic and phonological, using a large database of spontaneous speech in Japanese. At the acoustic level we show that, as has been documented before for phonemes, the realizations of words are more variable and less discriminable in IDS than in ADS. At the phonological level, we find an effect in the opposite direction: The IDS lexicon contains more distinctive words (such as onomatopoeias) than the ADS counterpart. Combining the acoustic and phonological metrics together in a global discriminability score reveals that the bigger separation of lexical categories in the phonological space does not compensate for the opposite effect observed at the acoustic level. As a result, IDS word forms are still globally less discriminable than ADS word forms, even though the effect is numerically small. We discuss the implication of these findings for the view that the functional role of IDS is to improve language learnability.     

The role of perceptual salience during the segmentation of connected speech

Statistical learning allows listeners to track transitional probabilities among syllable sequences and use these probabilities for subsequent speech segmentation. Recent studies have shown that other sources of information, such as rhythmic cues, can modulate the dependencies extracted via statistical computation. In this study, we explored how syllables made salient by a pitch rise affect the segmentation of trisyllabic words from an artificial speech stream by native speakers of three different languages (Spanish, English, and French). Results showed that, whereas performance of French participants did not significantly vary across stress positions (likely due to language-specific rhythmic characteristics), the segmentation performance of Spanish and English listeners was unaltered when syllables in word-initial and word-final positions were salient, but it dropped to chance level when salience was on the medial syllable. We argue that pitch rise in word-medial syllables draws attentional resources away from word boundaries, thus decreasing segmentation effectiveness.     

Screaming, yelling, whining, and crying: categorical and intensity differences in vocal expressions of anger and sadness in children's tantrums

Young children's temper tantrums offer a unique window into the expression and regulation of strong emotions. Previous work, largely based on parental report, suggests that two emotions, anger and sadness, have different behavioral manifestations and different time courses within tantrums. Individual motor and vocal behaviors, reported by parents, have been interpreted as representing different levels of intensity within each emotion category. The present study used high-fidelity audio recordings to capture the acoustic features of children's vocalizations during tantrums. Results indicated that perceptually categorized screaming, yelling, crying, whining, and fussing each have distinct acoustic features. Screaming and yelling form a group with similar acoustic features while crying, whining, and fussing form a second acoustically related group. Within these groups, screaming may reflect a higher intensity of anger than yelling while fussing, whining, and crying may reflect an increasing intensity of sadness.