Tonal cues to prosodic structure in rate-dependent speech perception.

This study explores how listeners integrate tonal cues to prosodic structure with their perception of local speech rate and consequent interpretation of durational cues. In three experiments, we manipulate the pitch and duration of speech segments immediately preceding a target sound along a vowel duration continuum (cueing coda stop voicing), testing how listeners' categorization of vowel duration shifts based on temporal and tonal context. We find that listeners perceive the presence of a phrasal boundary tone on a lengthened syllable as signaling a slowdown in speech rate, shifting perception of vowel duration, with effects that are additive when crossed in a 2 × 2 (pitch × duration) design. However, an asymmetrical effect of pitch and duration is found in an explicit duration judgement task in which listeners judge how long a pre-target syllable sounds to them. In explicit rate judgement, only durational information is consequential, unlike the categorization task, suggesting that integration of tonal and durational prosodic cues in rate-dependent perception is limited to implicit processing of speech rate. Results are discussed in terms of linguistic information in rate-dependent speech processing, the integration of prosodic cues, and implicit and explicit rate processing tasks.

Perceptual integration of pitch and duration: Prosodic and psychoacoustic influences in speech perception.

Two experiments explored how pitch influences perception of vowel duration as a cue to voicing in light of (1) psychoacoustic interactions between pitch and duration and (2) predicted compensatory effects based on the patterning of pitch and duration in the accentual/prominence-marking system of English. Listeners categorized a "coat"-"code" vowel duration continuum with pitch height on the vowel manipulated. In experiment 1 the expected psychoacoustic effect was observed. In experiment 2 the continuum was altered, highlighting pitch as a prosodic property, resulting in predicted compensatory effects. Results thus indicate prosodic patterns can mediate the perception of durational cues in isolated words.

Priming Implicit Prosody: Prosodic Boundaries and Individual Differences.

Using the structural priming paradigm, the present study explores predictions made by the implicit prosody hypothesis (IPH) by testing whether an implicit prosodic boundary generated from a silently read sentence influences attachment preference for a novel, subsequently read sentence. Results indicate that such priming does occur, as evidenced by an effect on relative clause attachment. In particular, priming an implicit boundary directly before a relative clause--cued by commas in orthography--encouraged high attachment of that relative clause, although the size of the effect depended somewhat on individual differences in pragmatic/communication skills (as measured by the Autism Spectrum Quotient). Thus, in addition to supporting the basic claims of the IPH, the present study demonstrates the relevance of such individual differences to sentence processing, and that implicit prosodic structure, like syntactic structure, can be primed.

The effect of age on the acquisition of second language prosody.

This study reports an exploratory analysis of the age of arrival (AoA) effect on the production of second language (L2) prosody. Three groups of Mandarin-speaking immigrants (N=10 in each group) with varying AoA in the United States and ten native speakers of English as controls participated in the study. All participants read a paragraph of English, and their speech samples were subjected to three prosodic analyses: speech and articulation rates, native speakers' judgment of the prosody based on segment-filtered speech, and analyses of tones and prosodic groupings using the Mainstream American English Tones and Break Indices (MAE_ToBI) transcription conventions. The L2 groups also filled out a survey providing information about their demographic background, English input, and socio-psychological aspects of language learning. The results revealed that the AoA factor impacted different aspects of prosody to varying degrees. Group differences were statistically significant for speech rate, degree of foreign prosody, the frequency of pitch accents, and the frequency of high boundary tones (H-H%). However,group differences were not significant for articulation rate, prosodic groupings, and the rest of the ToBI-labeled phonological categories. Multiple regression analyses further confirmed the AoA effect on degree of foreign prosody, the frequency of pitch accents, and high boundary tones (H-H%); AoA remained a significant predictor controlling for the effects of other variables. However, speech rate was predicted by English media exposure and motivation variable but not by AoA.

Early childhood language memory in the speech perception of international adoptees.

It is as yet unclear whether the benefits of early linguistic experiences can be maintained without at least some minimal continued exposure to the language. This study compared 12 adults adopted from Korea to the US as young children (all but one prior to age one year) to 13 participants who had no prior exposure to Korean to examine whether relearning can aid in accessing early childhood language memory. All 25 participants were recruited and tested during the second week of first-semester college Korean language classes. They completed a language background questionnaire and interview, a childhood slang task and a Korean phoneme identification task. Results revealed an advantage for adoptee participants in identifying some Korean phonemes, suggesting that some components of early childhood language memory can remain intact despite many years of disuse, and that relearning a language can help in accessing such a memory.

Salvaging a Childhood Language.

Childhood experience with a language seems to help adult learners speak it with a more native-like accent. Can analogous benefits be found beyond phonology? This study focused on adult learners of Spanish who had spoken Spanish as their native language before age 7 and only minimally, if at all, thereafter until they began to re-learn Spanish around age 14 years. They were compared with native speakers, childhood overhearers, and typical late-second-language (L2)-learners of Spanish. Both childhood speakers and overhearers spoke Spanish with a more native-like accent than typical late-L2-learners. On grammar measures, childhood speakers-although far from native-like-reliably outperformed childhood overhearers as well as typical late-L2-learners. These results suggest that while simply overhearing a language during childhood could help adult learners speak it with a more native-like phonology, speaking a language regularly during childhood could help re-learners use it with more native-like grammar as well as phonology.

Production benefits of childhood overhearing.

The current study assessed whether overhearing Spanish during childhood helps later Spanish pronunciation in adulthood. Our preliminary report based on a subset of the data [Au et al., Psychol. Sci. 13, 238-243 (2002)] revealed that adults who overheard Spanish during childhood had better Spanish pronunciation, but not better morphosyntax, than adult learners of Spanish who had no childhood experience with Spanish. We now present data from the full sample with additional morphosyntax and pronunciation assessments, as well as measures to help rule out possible confounding prosodic factors such as speech rate, phrasing, and stress placement. Three groups of undergraduates were compared: 15 Spanish-English bilinguals (native Spanish speakers), 15 late learners of Spanish who overheard Spanish during childhood (childhood overhearers), 15 late learners of Spanish who had no regular experience with Spanish until middle or high school (typical late L2 learners). Results confirmed a pronunciation advantage for the childhood overhearers over the typical late L2 learners on all measures: phonetic analyses (VOT and degree of lenition), accent ratings (phoneme and story production), but no benefit in morphosyntax. Importantly, the pronunciation advantage did not seem attributable to prosodic factors. These findings illustrate the specificity of overhearers' advantage to phonological production.

Prosodic phrasing and attachment preferences.

The attachment of a relative clause (RC) has been found to differ across languages when its head noun is a complex NP. One attempt to explain the attachment differences is the Implicit Prosody Hypothesis (IPH) proposed by Fodor (1998, 2002). The goal of this paper is to show how the default phrasing of a sentence (explicit prosody), defined phonologically, differs across seven languages (English, Greek, Spanish, French, Farsi, Japanese, and Korean), and how the prosodic phrasing of a sentence in each language, both default and nondefault, matches the interpretation of RC attachment by individual speakers. Observed tendencies show that there is a direct relationship between the prosodic phrasing and the interpretation of RC attachment, strongly supporting the IPH. In addition, the paper discusses the status of default phrasing and the factors affecting the default phrasing, including rhythmic and syntactic factors and their interactions.

Holding on to childhood language memory.

While early language experience seems crucial for mastering phonology, it remains unclear whether there are lasting benefits of speaking a language regularly during childhood if the quantity and quality of speaking drop dramatically after childhood. This study explored the accessibility of early childhood language memory. Specifically, it compared perception and production of Korean speech sounds by childhood speakers who had spoken Korean regularly for a few years during childhood to those of two other groups: (1) childhood hearers who had heard Korean regularly during childhood but had spoken Korean minimally, if at all; and (2) novice learners. All three groups were enrolled in first-year college Korean language classes. Childhood speakers were also compared to native speakers of Korean to see how native-like they were. The results revealed measurable long-term benefits of childhood speaking experience, underscoring the importance of early language experience, even if such experience diminishes dramatically beyond childhood.

Overhearing a language during childhood.

Despite its significance for understanding of language acquisition, the role of childhood language experience has been examined only in linguistic deprivation studies focusing on what cannot be learned readily beyond childhood. This study focused instead on long-term effects of what can be learned best during childhood. Our findings revealed that adults learning a language speak with a more native like accent if they overheard the language regularly during childhood than if they did not. These findings have important implications for understanding of language-learning mechanisms and heritage-language acquisition.