Journal of speech and hearing research最新文献

This study investigated the persistence of non-standard dialect production among 114 African American and White children in grades 3, 5, and 7. A dialect shift premise suggests that a large and uniform decline in dialectal features occurs in the language of school-age children. Three experimental tasks were administered. The results indicated that dialect awareness and discrimination increased as grade in school increased; a dialect shift occurred between grades 3 and 5; non-standard dialect production and comprehension of standard dialect were not associated; and that there was no difference in non-standard dialect production among African American and White students.

In this paper, we address a number of issues in speech research in the context of the equilibrium point hypothesis of motor control. The hypothesis suggests that movements arise from shifts in the equilibrium position of the limb or the speech articulator. The equilibrium is a consequence of the interaction of central neural commands, reflex mechanisms, muscle properties, and external loads, but it is under the control of central neural commands. These commands act to shift the equilibrium via centrally specified signals acting at the level of the motoneurone (MN) pool. In the context of a model of sagittal plane jaw and hyoid motion based on the lambda version of the equilibrium point hypothesis, we consider the implications of this hypothesis for the notion of articulatory targets. We suggest that simple linear control signals may underlie smooth articulatory trajectories. We explore as well the phenomenon of intraarticulator coarticulation in jaw movement. We suggest that even when no account is taken of upcoming context, that apparent anticipatory changes in movement amplitude and duration may arise due to dynamics. We also present a number of simulations that show in different ways how variability in measured kinematics can arise in spite of constant magnitude speech control signals.

Studies of children's speech perception have shown that young children process speech signals differently than adults. Specifically, the relative contributions made by various acoustic parameters to some linguistic decisions seem to differ for children and adults. Such findings have led to the hypothesis that there is a developmental shift in the perceptual weighting of acoustic parameters that results from experience with a native language (i.e., the Developmental Weighting Shift). This developmental shift eventually leads the child to adopt the optimal perceptual weighting strategy for the native language being learned (i.e., one that allows the listener to make accurate decisions about the phonemic structure or his or her native language). Although this proposal has intuitive appeal, there is at least one serious challenge that can be leveled against it: Perhaps age-related differences in speech perception can appropriately be explained by age-related differences in basic auditory-processing abilities. That is, perhaps children are not as sensitive as adults to subtle differences in acoustic structure and so make linguistic decisions based on the acoustic information that is most perceptually salient. The present study tested this hypothesis for the acoustic cues relevant to fricative identity in fricative-vowel syllables. Results indicated that 3-year-olds were not as sensitive to changes in these acoustic cues as adults are, but that these age-related differences in auditory sensitivity could not entirely account for age-related differences in perceptual weighting strategies.

Anatomical and physiological changes of the speech production mechanism that occur with aging may result in phonatory distinctions between older and younger speakers. This investigation examined amplitude-based glottal airflow characteristics from sustained vowel production in healthy adult women. Sixty women participated in this study, 10 each in six age groups of 20-, 30-, 40-, 50-, 60-, and 70-year-olds. Measures included peak, alternating, and minimum glottal airflow. Additionally, a ratio of minimum to peak glottal airflow was calculated. Results from an analysis of variance indicated no significant group mean difference for any of the dependent measures. A greater variability in peak glottal airflow for the 70-year-old age group as compared to the 20-year-old age group was found. None of the dependent variables were significantly related to age and therefore were not good predictors of age. The results imply that laryngeal senescence in healthy women may not be significant enough to affect the magnitude of phonatory function parameters. Either the assumed anatomical changes produce less significant phonatory change in the healthy individual or the healthy individual is more capable of using strategies to counteract degenerative laryngeal changes.

Digital filters with conventional lowpass, highpass, bandpass, and band reject frequency response curves are perfectly adequate for many research applications in speech and hearing. However, there are some specialized applications for which these conventional response characteristics are less than ideal. In this paper we describe a simple method for generating digital filters with virtually any amplitude and phase response. The process involves (a) calculating the impulse response of a finite impulse response filter from a text file that specifies the desired magnitude and phase response of the filter, and (b) convolving the impulse response with the input signal. Sample applications of this method are described.

Initial language assessments are used not only to determine the presence of a language problem and establish eligibility for intervention, but also to provide information about a child's readiness for immediate change in language growth. This study explored static assessment profiling (specific variables and discrepancies in performance) and dynamic assessment results to determine their relative effectiveness for predicting immediate change. Correlation data were used to examine how well each assessment measure predicted upcoming language production changes for children with specific expressive language impairment. Results indicated that dynamic assessment outcomes were most highly correlated with immediate language growth, followed by discrepancy in receptive and expressive language age. Findings are discussed in terms of their clinical and theoretical importance.

In this developmental study, idiom understanding was examined in Australian students from Grades 5 and 8 (n = 50 per group; mean ages = 10.7 and 13.8, respectively). Twenty-four idioms with familiarity ratings ranging from high to low (as judged by Australian adolescents) were each presented in a brief story context. The students read each story and selected the best interpretation of the idiom from a set of four answer choices. Results indicated that performance on the task improved as a function of increasing grade level and that idiom familiarity was significantly correlated to idiom understanding for both groups of students. These results, which were consistent with a previous study of American students of comparable educational levels (Nippold & Taylor, 1995), provide further support for the "language experience" hypothesis of figurative language development. In replicating the previous developmental study, evidence of external validity is provided.

Previous studies with fricative-vowel (FV) syllables have shown that the difference in overall spectrum between fricatives is less in children's speech than in that of adults, but that fricative noises show greater differences in the region of the second formant (F2) as a function of the upcoming vowel than those of adults at corresponding points in the fricative. These results have been interpreted as evidence that children produce fricatives that are not spatially differentiated as those of adults and that children initiate vowel gestures earlier during syllable production than adults do (Nittrouer, Studdert-Kennedy, & McGowan, 1989). The goals of the present study were (a) to replicate the previous age-related difference for F2 with FV syllables; (b) to test the alternative interpretation that age-related differences in fricative f2 reflect age-related differences in vocal-tract geometry; (c) to determine whether age-related differences in F2 (and so, by inference, in articulatory organization) might extend beyond the syllable boundaries, perhaps into the schwa of a preceding unstressed syllable; and (d) determine if gestures other than fricative gestures show less spatial differentiation in children's than in adults' speech. To these ends, F2 frequencies were measured in schwa-fricative-vowel utterances (consisting of the fricatives /s/ and [symbol:see text] and of the vowels /i/ and /a/) from 40 speakers (10 each of the ages of 3, 5, 7 years, and adults) at three locations (for the entire schwa, for 10 ms of fricative noise centered at 30 ms before voicing onset, and 10 pitch periods from vocalic center). Results of several analyses supported four conclusions: (a) the earlier finding was replicated; (b) age-related differences in vocal-tract geometry could not explain the age-related difference in vowel effects on fricative noise; (c) children master intersyllabic gestural organization prior to intrasyllabic gestural organization; and (d) unlike fricative gestures, children's vowel gestures are more spatially distinct than those of adults.

The purpose of this study was to evaluate whether the Covert Repair Hypothesis (CRH; Postma & Kolk, 1993), a theory designed to account for the occurrence of speech disfluencies in adults who stutter, can also account for selected speech characteristics of children who stutter and demonstrate disordered phonology. Subjects were 9 boys who stutter and exhibit normal phonology (S + NP; mean age = 61.33 months; SD = 10.16 months) and 9 boys who stutter and exhibit disordered phonology (S + DP; mean age = 59.11 months; SD = 9.37 months). Selected aspects of each child's speech fluency and phonology were analyzed on the basis of an audio/videotaped picture-naming task and a 30-min conversational interaction with his mother. Results indicated that S + NP and S + DP children are generally comparable in terms of their basic speech disfluency, nonsystematic speech error, and self-repair behaviors. CRH predictions that utterances produced with faster articulatory speaking rates or shorter response time latencies are more likely to contain speech errors or speech disfluencies were not supported. CRH predictions regarding the co-occurrence of speech disfluencies and speech errors were supported for nonsystematic ("slip-of-the-tongue"), but not for systematic (phonological process/rule-bases), speech errors. Furthermore, neither S + NP nor S + DP subjects repaired their systematic speech errors during conversational speech, suggesting that systematic deviations from adult forms may not represent true "errors, " at least for some children exhibiting phonological processes. Findings suggest that speech disfluencies may not represent by-products of self-repairs of systematic speech errors produced during conversational speech, but that self-repairs of nonsystematic speech errors may be related to children's production of speech disfluencies.

The effect of frequency alterations in auditory feedback of people who stutter on stuttering frequency was investigated. Twelve participants who stutter read aloud under nonaltered auditory feedback (NAF) and four conditions of frequency-altered feedback ([FAF], plus/minus one-half and one-quarter octaves) at normal and fast speech rates. Stuttering frequency was significantly higher while reading aloud with NAF relative to the four conditions of FAF (p < 0.05). There were no differences among participants' stuttering frequency between the four FAF conditions (p > 0.05). Reductions in stuttering frequency of approximately 50% to 60% were found with FAF relative to NAF. More disfluencies occurred with the fast versus the normal speech rate condition (p = .0007) irrespective of auditory feedback condition. These findings suggest that slight alterations in the frequency of auditory feedback of people who stutter are fluency-enhancing.