The link between prosody and language skills in children with specific language impairment (SLI) and/or dyslexia.

BACKGROUND: Children with specific language impairment (SLI) and dyslexia are known to have impairments in various aspects of phonology, which have been claimed to cause their language and literacy impairments. However, 'phonology' encompasses a wide range of skills, and little is known about whether these phonological impairments extend to prosody. AIMS: To investigate certain prosodic abilities of children with SLI and/or dyslexia, to determine whether such children have prosodic impairments, whether they have the same pattern of impairments, and whether prosodic impairments are related to language and literacy deficits. METHODS & PROCEDURES: Six subtests of the Profiling Elements of Prosodic Systems - Child version (PEPS-C) were used to investigate discrimination/comprehension and imitation/production of prosodic forms that were either independent of language or that had one of two linguistic functions: chunking (prosodic boundaries) and focus (contrastive stress). The performance of three groups of 10-14-year-old children with SLI plus dyslexia, SLI, and dyslexia were compared with an age-matched control group and two younger control groups matched for various aspects of language and reading. OUTCOMES & RESULTS: The majority of children with SLI and/or dyslexia performed well on the tasks that tested auditory discrimination and imitation of prosodic forms. However, their ability to use prosody to disambiguate certain linguistic structures was impaired relative to age-matched controls, although these differences disappeared in comparison with language-matched controls. No, or only very weak, links were found between prosody and language and literacy skills in children with SLI and/or dyslexia. CONCLUSIONS & IMPLICATIONS: Children with SLI and/or dyslexia aged 10-14 years show an impaired ability to disambiguate linguistic structures for which prosody is required. However, they are able on the whole to discriminate and imitate the actual prosodic structures themselves, without reference to linguistic meaning. While the interaction between prosody and other components of language such as syntax and pragmatics is problematic for children with SLI and/or dyslexia, prosody itself does not appear to be a core impairment.

Measurements of steady turbulent flow through a rigid simulated collapsed tube.

Axial and transverse components of liquid velocity are measured by laser Doppler anemometer in a perspex tube that has been deformed at one point to resemble the shape of the throat of a partially collapsed flexible tube, conveying fluid while being compressed externally. The Reynolds number is 5900. The flow down-stream of the throat consists of two side-jets with reverse flow extending all across the cross-section between them. The jets spread out around the central retrograde-flow zone, initially forming crescents of high-speed forward flow and then, at three diameters downstream, an almost complete annulus of forward flow around a central zone of lower-speed but now forward flow. Comparison is made between the features of this turbulent flow and those of a previously investigated laminar flow through the same geometry. In both, retrograde flow ceases between two and three diameters downstream of the centre of the throat. However, the laminar flow is annular at three diameters downstream, whereas here the jets remain influential at that station. The maximum normalised turbulence intensity exceeds 1.35.

Outstanding questions about phonological processing in dyslexia.

It is widely accepted that developmental dyslexia results from some sort of phonological deficit. Yet, it can be argued that phonological representations and their processing have been insufficiently tested in dyslexia research. Firstly, claims about how tasks tap into certain kinds of representations or processes are best appreciated in the light of an explicit information-processing model. Here, a cognitive model of lexical access is described, incorporating speech perception, reading and object recognition. The model emphasizes that phonological forms of lexical items are distinct from non-lexical phonological representations. Secondly, phonology, as a linguistic discipline, teaches us that there is much more to it than phonemic categorization and awareness. The phonological level of representation also embodies phonotactic regularities, patterns of phoneme assimilation and alternation, as well as supra-segmental knowledge pertaining to syllable structure, stress, intonation and rhythm. All these aspects are in part language-dependent, and therefore must be learnt by children in order to become proficient native speakers and listeners. If phonological representations were affected in dyslexia, dyslexic children would presumably have difficulties acquiring these aspects of their language. This prediction is as yet untested. A possible research agenda is outlined, aiming to provide a more comprehensive assessment of the phonological theory of dyslexia.

Correlates of linguistic rhythm in the speech signal.

Spoken languages have been classified by linguists according to their rhythmic properties, and psycholinguists have relied on this classification to account for infants' capacity to discriminate languages. Although researchers have measured many speech signal properties, they have failed to identify reliable acoustic characteristics for language classes. This paper presents instrumental measurements based on a consonant/vowel segmentation for eight languages. The measurements suggest that intuitive rhythm types reflect specific phonological properties, which in turn are signaled by the acoustic/phonetic properties of speech. The data support the notion of rhythm classes and also allow the simulation of infant language discrimination, consistent with the hypothesis that newborns rely on a coarse segmentation of speech. A hypothesis is proposed regarding the role of rhythm perception in language acquisition.

Language discrimination by human newborns and by cotton-top tamarin monkeys.

Humans, but no other animal, make meaningful use of spoken language. What is unclear, however, is whether this capacity depends on a unique constellation of perceptual and neurobiological mechanisms or whether a subset of such mechanisms is shared with other organisms. To explore this problem, parallel experiments were conducted on human newborns and cotton-top tamarin monkeys to assess their ability to discriminate unfamiliar languages. A habituation-dishabituation procedure was used to show that human newborns and tamarins can discriminate sentences from Dutch and Japanese but not if the sentences are played backward. Moreover, the cues for discrimination are not present in backward speech. This suggests that the human newborns' tuning to certain properties of speech relies on general processes of the primate auditory system.

Correlates of linguistic rhythm in the speech signal.

Spoken languages have been classified by linguists according to their rhythmic properties, and psycholinguists have relied on this classification to account for infants' capacity to discriminate languages. Although researchers have measured many speech signal properties, they have failed to identify reliable acoustic characteristics for language classes. This paper presents instrumental measurements based on a consonant/vowel segmentation for eight languages. The measurements suggest that intuitive rhythm types reflect specific phonological properties, which in turn are signaled by the acoustic/phonetic properties of speech. The data support the notion of rhythm classes and also allow the simulation of infant language discrimination, consistent with the hypothesis that newborns rely on a coarse segmentation of speech. A hypothesis is proposed regarding the role of rhythm perception in language acquisition.

Language identification with suprasegmental cues: a study based on speech resynthesis.

This paper proposes a new experimental paradigm to explore the discriminability of languages, a question which is crucial to the child born in a bilingual environment. This paradigm employs the speech resynthesis technique, enabling the experimenter to preserve or degrade acoustic cues such as phonotactics, syllabic rhythm, or intonation from natural utterances. English and Japanese sentences were resynthesized, preserving broad phonotactics, rhythm, and intonation (condition 1), rhythm and intonation (condition 2), intonation only (condition 3), or rhythm only (condition 4). The findings support the notion that syllabic rhythm is a necessary and sufficient cue for French adult subjects to discriminate English from Japanese sentences. The results are consistent with previous research using low-pass filtered speech, as well as with phonological theories predicting rhythmic differences between languages. Thus, the new methodology proposed appears to be well suited to study language discrimination. Applications for other domains of psycholinguistic research and for automatic language identification are considered.