Measures Of Speech Processing Research Articles

The development of children at familial risk for dyslexia: Birth to early school age

Children at risk for familial dyslexia (n = 107) and their controls (n = 93) have been followed from birth to school entry in the Jyvaskyla Longitudinal study of Dyslexia (JLD) on developmental factors linked to reading and dyslexia. At the point of school entry, the majority of the at-risk children displayed decoding ability that fell at least 1 SD below the mean of the control group. Measures of speech processing were the earliest indices to show both group differences in infancy and also significant predictive associations with reading acquisition. A number of measures of language, including phonological and morphological skill collected repeatedly from age three, revealed group differences and predictive correlations. Both the group differences and the predictive associations to later language and reading ability strengthened as a function of increasing age. The predictions, however, tend to be stronger and the spectrum of significant correlations wider in the at-risk group. These results are crucial to early identification and intervention of dyslexia in at-risk children.

Low commonality between tests of auditory discrimination and of speech perception

The relation between measures of speech processing and of fine auditory discrimination abilities was investigated by means of factor analyses of the performance of normal listeners on the Test of Basic Auditory Capabilities, TBAC [Watson et al., J. Acoust. Soc. Am. Suppl. 1 71, S72 (1982)]. The eight subtests of the TBAC include syllable identification in noise and discrimination of (a) changes in frequency, intensity, and duration in 1.0‐kHz sinusoids; (b) “jitter” within a pulse train; (c) temporal order for sinusoids and nonsense syllables; and (d) detection of single‐component changes in word‐length tonal patterns. Data were collected in a field (n = 127) and using earphones (n = 119). Test reliability was high in both presentation conditions. Average performance was slightly higher with earphones for discrimination of intensity, of tonal patterns, and in the two speech subtests. Both groups showed large ranges of individual performance on all subtests. Factor analyses revealed similar structures for both groups, consisting essentially of two factors loaded on the nonspeech tests (complex sound/pitch and duration/intensity) and a third that is mainly a speech factor. This result, and the associated inter‐test correlations, points towards only a very weak relation between listeners' measured abilities to hear out fine details of acoustic waveforms and their skill at identifying speech sounds. [Work supported by NIH and AFOSR.]

Correlations between auditory capabilities and measures of phoneme perception

Performance of 32 normal‐hearing listeners on the test of basic auditory capabilities [Watson et al., J. Acoust. Soc. Am. Suppl. I 71, S73 (1982)] was correlated with each of the following measures of phoneme perception (obtained with the CUNY Nonsense Syllable Test): (l) hit probability for the overall test, and for each individual phoneme; (2) P(C)max for identification of each individual phoneme; and (3) P(C)max for discrimination of each possible phoneme pair within a set of phonemes. Relative to the total number of correlations that can be calculated, the percentage of significant correlations (p < 0.05, n = 32) were 0% for overall hit probability, 10% for phoneme‐specific hit probability, 17% for identification P(C)max and 10% for pairwise discrimination P(C)max. These results support the hypothesis [Espinoza‐Varas and Watson, J. Acoust. Son. Am. Suppl. 1 78, S47 (1985)] that auditory capabilities may be correlated more strongly with the ability to process specific phonemes than with overall measures of speech processing (e.g., whole‐test speech discrimination scores). It was also found that a number of phonemes yielding either near‐chance or near‐perfect performance contribute little or nothing to the correlations or, presumably, to the information provided by the overall speech score. [Work supported by NIH and AFOSR.]

Basic auditory capabilities and resolving power for phonemes

Efforts to relate performance on speech test to general auditory abilities have yielded conflicting evidence. One possible reason is that the resolving power for individual psychoacoustic dimensions is related more closely to the ability to resolve acoustic details of individual phonemes, than to global speech perception as assessed by the overall percent of tokens correctly identified on a speech test. Auditory capabilities were measured with a battery of psychoacoustic tests [Watson et al., J. Acoust. Soc. Am. Suppl. 1 71, S73 (1982)]. Speech perception ability was studied with seven subtests of the CUNY Nonsense Syllable Test, NST (presented in quiet, 33 dB SPL). Indices of speech perception were derived for each individual phoneme, overall for each subtest, and overall for the seven NST subtests. Results from 34 normal listeners showed: (1) large differences in identification accuracy of phonemes within a subtest, which are not reflected in the overall measures; (2) strong biases towards specific phonemes within a subtest; and (3) differences in identification of an individual phoneme depending on the specific subtest in which it occurs. Thus the overall measures of speech processing are poor indicators of the ability to resolve specific phonemes. This result, together with the fact that phonetic distinctions are cued by multiple (redundant) cues, suggests that correlations between overall speech measures and auditory capabilities may be expected to be moderate or low. [Supported by NIH and AFOSR.]