Cross-language speech perception: Initial capabilities and developmental change.

Abstract

This article reports three studies designed to increase our understanding of developmental changes in cross-language speech perception. In the first study, we compared adult speakers of English and Hindi on their ability to discriminate pairings from a synthetic voiced, unaspirated place-of-articulation continuum. Results indicated that English listeners discriminate two categories (ba vs. (Ja), whereas Hindi listeners discriminate three (ba vs. da, and da vs. Da). We then used stimuli from within this continuum in the next two experiments to determine (a) if our previously reported finding (Werker & Tees, 1984a) of a reorganization between 6 and 12 months of life from "universal" to "language-specific" phonetic perception would be evident using synthetic (rather than natural) stimuli in which the physical variability within and between categories could be controlled, and (b) whether the younger infants' sensitivity to nonnative speech contrasts is best explained by reference to the phonetic relevance or the physical similarity of the stimuli. In addition to replicating the developmental reorganization, the results indicate that infant speech perception is phonetically relevant. We discuss the implications of these results.Since the early 1970s researchers have been studying infant speech perception, partly in an attempt to determine if there is evidence for a specialized phonetic mode of processing among infants. In a now-classic study, Eimas, Siqueland, Jusczyk, and Vigorito (1971) demonstrated that English-learning infants aged 1 to 4 months show far better discrimination along a synthetic voice onset time (VOT) continuum for two stimuli that straddle the adult /ba/-/pa/ phonetic category boundary than they do for two equally acoustically distinct stimuli from within the same phonetic category. This differential discrimination at some, rather than other, points along a single synthetic continuum indicates that speech perception may be "categorical" in infants. This finding has now been replicated many times with infants using several other distinctions (for reviews, see Aslin, 1987;Kuhl, 1987).

Understanding spatial relations: Flexible infants, lexical adults

“…Our data more generally indicate that once children acquire the semantic system of their own language, their nonlinguistic sensitivity to those distinctions not made in their language diminishes over time. There appear to be similarities between the loss in sensitivity to tight versus loose fitting aspects of containment by English speakers shown in Experiment 2 and the loss of phonetic contrasts that are not phonemic in oneÕs native tongue (Kuhl, Williams, Lacerda, Stevens, & Lindblom, 1992;Werker & Lalonde, 1988). But there are many differences between the perceptual tuning of the sounds of oneÕs language and the conceptual tuning of semantic categories that result from what the language emphasizes.…”

Speech perception skills of deaf infants following cochlear implantation: a first report

“…During the second half of the first year of life, the initial, language-general speech perception capacities develop into language-specific speech perception skills [11,19,22,23]. For example, Wer-ker and Tees [22] tested English-learning 6-8-month-olds and 10-12-month-olds' ability to detect sound contrasts that were distinctive in Hindi but not in English.…”

Individual differences in the acquisition of second language phonology

“…Retroflex consonants require a relatively complex articulation, and are rare across languages; only 11% of the world's languages include a retroflex consonant (Burnham, 1986). Infants under the age of 6 months raised in an English-speaking environment can hear the difference between the retroflex and alveolar sounds, but sensitivity to this difference diminishes during the first year of life (Werker, Gilbert, Humphrey, & Tees, 1981;Werker & Lalonde, 1988). As a result, adult English listeners assimilate the alveolar and retroflex sounds such that they perceive both sounds as instances of the alveolar consonant (Polka, 1991;RiveraGaxiola et al, 2000a;Werker & Lalonde, 1988).…”

“…For example, native English speakers typically cannot hear the difference between the English alveolar and the Hindi retroflex stop consonants. So even though native speakers of Indian languages hear the difference as easily as anyone reading this paper can hear the difference between 'b' and 'd', to native English speakers, both are heard as the voiced alveolar stop consonant 'd' (Polka, 1991;Rivera-Gaxiola, Csibra, Johnson, & KarmiloffSmith, 2000a;Werker & Lalonde, 1988). There is evidence, however, for considerable variability across individuals in the learning of speech sounds that involve rapid spectral change, in particular ones that contrast place of articulation, such as the r/l contrast for native Japanese listeners, or the dental-retroflex one for native English speakers.…”

“…Infants under the age of 6 months raised in an English-speaking environment can hear the difference between the retroflex and alveolar sounds, but sensitivity to this difference diminishes during the first year of life (Werker, Gilbert, Humphrey, & Tees, 1981;Werker & Lalonde, 1988). As a result, adult English listeners assimilate the alveolar and retroflex sounds such that they perceive both sounds as instances of the alveolar consonant (Polka, 1991;RiveraGaxiola et al, 2000a;Werker & Lalonde, 1988). Training-related improvement has been previously shown using naturalistic versions of this contrast in English speakers, but mainly under conditions that place relatively fewer demands on working memory, for example with the use of an AX discrimination task with a relatively short inter-stimulus interval (ISI), or with the use of truncated stimuli (Pruitt, Jenkins, & Strange, 2006;Pruitt et al, 1990;Werker & Logan, 1985;Werker & Tees, 1984b).…”