Speaking Rate, Oro-Laryngeal Timing, and Place of Articulation Effects on Burst Amplitude: Evidence From English and Tamil.

The relationship between speaking rate and burst amplitude was investigated in plosives with differing oro-laryngeal timing: long-lag voice-onset time (VOT) (North American English) and short-lag VOT (Indian Tamil). Burst amplitude (reflecting both intraoral pressure and flow geometry of the oral channel) was hypothesized to decrease in pre-vocalic plosive syllables with the increase in speaking rate, which imposes temporal constraints on both intraoral pressure buildup behind the oral occlusion and respiratory air flow. The results showed that decreased vowel duration (which is associated with increased speaking rate) led to decreased burst amplitude in both short- and long-lag plosives. Aggregate models of bilabial and velar plosives (found in both languages) suggested lower burst amplitudes in short-lag stops. Place-of-articulation effects in both languages were consistent with models of stop consonant acoustics, and place interactions with vowel duration were most apparent with long-lag English stops. The results are discussed in terms of speaking rate and language-internal forces, contributing to burst amplitude variation and their implications for speech perception and potential to affect lenition phenomena.

Words Get in the Way: Linguistic Effects on Talker Discrimination.

A speech perception experiment provides evidence that the linguistic relationship between words affects the discrimination of their talkers. Listeners discriminated two talkers' voices with various linguistic relationships between their spoken words. Listeners were asked whether two words were spoken by the same person or not. Word pairs varied with respect to the linguistic relationship between the component words, forming either: phonological rhymes, lexical compounds, reversed compounds, or unrelated pairs. The degree of linguistic relationship between the words affected talker discrimination in a graded fashion, revealing biases listeners have regarding the nature of words and the talkers that speak them. These results indicate that listeners expect a talker's words to be linguistically related, and more generally, indexical processing is affected by linguistic information in a top-down fashion even when listeners are not told to attend to it.

Speech rate and pitch characteristics of infant-directed speech: Longitudinal and cross-linguistic observations.

The speech rate and pitch (F0) characteristics of naturalistic, longitudinally recorded infant- and adult-directed speech are reported for three, genetically diverse languages. Previous research has suggested that the prosodic characteristics of infant-directed speech are slowed speech rate, raised mean pitch, and expanded pitch range relative to adult-directed speech. Sixteen mothers (5 Sri Lankan Tamil, 5 Tagalog, 6 Korean) were recorded in their homes during natural interactions with their young infants, and adults, over the course of 12 months beginning when the infant was 4 months old. Regression models indicated that the difference between infant- and adult-directed speech rates decreased across the first year of infants' development. Models of pitch revealed predicted differences between infant- and adult-directed speech but did not provide evidence for cross-linguistic or longitudinal effects within the time period investigated for the three languages. The universality of slowed speech rate, raised pitch, and expanded pitch range is discussed in light of individuals' highly variable implementation of these prosodic features in infant-directed speech.

Phonetic category cues in adult-directed speech: evidence from three languages with distinct vowel characteristics

Utilizando un lenguaje artificial Maye, Werker, y Gerken (2002) demostraron que las categorías fonéticas de los bebés cambian en función de la distribución de los sonidos del habla. En un estudio reciente, Werker y cols. (2007) observaron que el habla dirigida a bebés (habla maternal) contiene claves acústicas fiables que sustentan el aprendizaje de las categorías vocálicas propias de la lengua: las pistas en inglés eran espectrales y de duración; las pistas en japonés eran exclusivamente de duración. En el presente estudio se amplían estos resultados de dos formas, 1) examinamos una nueva lengua, el catalán, que distingue las vocales únicamente a partir de las diferencias espectrales, y 2) ya que los bebés aprenden también del habla dirigida a los adultos (Oshima-Takane, 1988), analizamos este tipo de habla en las tres lenguas. Los análisis revelaron diferencias considerables en las pistas de cada lengua, e indicaron que, por sí solas, son suficientes para establecer las categorías vocálicas específicas de cada lengua. Esta demostración de las diferencias propias de cada lengua en la distribución de las pistas fonéticas presentes en el habla dirigida al adulto, proporciona evidencia adicional sobre el tipo de pistas que pueden estar usando los bebés cuando establecen sus categorías fonéticas maternas(AU)

Using an artificial language learning manipulation, Maye, Werker, and Gerken (2002) demonstrated that infants’ speech sound categories change as a function of the distributional properties of the input. In a recent study, Werker et al. (2007) showed that Infant-directed Speech (IDS) input contains reliable acoustic cues that support distributional learning of language-specific vowel categories: English cues are spectral and durational; Japanese cues are exclusively durational. In the present study we extend these results in two ways. 1) we examine a language, Catalan, which distinguishes vowels solely on the basis of spectral differences, and 2) because infants learn from overheard adult speech as well as IDS (Oshima- Takane, 1988), we analyze Adult-directed Speech (ADS) in all three languages. Analyses revealed robust differences in the cues of each language, and demonstrated that these cues alone are sufficient to yield language-specific vowel categories. This demonstration of language-specific differences in the distribution of cues to phonetic category structure found in ADS provides additional evidence for the types of cues available to infants to guide their establishment of native phonetic categories(AU)

The interaction between acoustic salience and language experience in developmental speech perception: evidence from nasal place discrimination.

Previous research suggests that infant speech perception reorganizes in the first year: young infants discriminate both native and non-native phonetic contrasts, but by 10-12 months difficult non-native contrasts are less discriminable whereas performance improves on native contrasts. In the current study, four experiments tested the hypothesis that, in addition to the influence of native language experience, acoustic salience also affects the perceptual reorganization that takes place in infancy. Using a visual habituation paradigm, two nasal place distinctions that differ in relative acoustic salience, acoustically robust labial-alveolar [ma]-[na] and acoustically less salient alveolar-velar [na]-[ enga], were presented to infants in a cross-language design. English-learning infants at 6-8 and 10-12 months showed discrimination of the native and acoustically robust [ma]-[na] (Experiment 1), but not the non-native (in initial position) and acoustically less salient [na]-[ enga] (Experiment 2). Very young (4-5-month-old) English-learning infants tested on the same native and non-native contrasts also showed discrimination of only the [ma]-[na] distinction (Experiment 3). Filipino-learning infants, whose ambient language includes the syllable-initial alveolar (/n/)-velar (/ eng/) contrast, showed discrimination of native [na]-[ enga] at 10-12 months, but not at 6-8 months (Experiment 4). These results support the hypothesis that acoustic salience affects speech perception in infancy, with native language experience facilitating discrimination of an acoustically similar phonetic distinction [na]-[ enga]. We discuss the implications of this developmental profile for a comprehensive theory of speech perception in infancy.