The perceptual level functioning of dysphasic children

Phonemic discrimination and reproduction in 4-5-year-old children: Relations to hearing

OBJECTIVE

The long-term objective of this research is to highlight the importance of speech perception assessment in children with developmental language disorder (DLD), and to investigate how hearing contributes to speech and language skills. As a first step in fulfilling this aim, the present study explored relations between phonemic discrimination and reproduction, and sensitive measures of hearing in young healthy children.

METHODS

The American Listen-Say test was developed and served as speech perception tool. This test reports speech discrimination of phonemic contrasts quantitatively for both quiet and in noise conditions, along with reproduction scores, all measured within one session. Speech tokens were perceptually homogenized in noise. Forty-one 4-5-year-old American children participated. Phonemic discrimination (quiet and speech shaped noise) and phonemic reproduction, audiometric thresholds in the conventional (1-8 kHz) and extended high frequency (EHF; 10-16 kHz) range, and distortion product otoacoustic emissions (DPOAEs) were examined.

RESULTS

All children had normal hearing thresholds within the conventional range (mean PTA bilaterally 8.6 dB HL). Ten (24.3%) of the children had elevated EHF thresholds (> 20 dB HL) for one or more frequencies or ears, and six (14.6%) had DPOAE signal to noise ratios (SNR) < 6 dB. EHF thresholds and DPOAE SNRs were significantly associated. Children's phonemic discrimination was impaired in noise, relative to quiet. There was a moderate, significant correlation between overall phonemic discrimination in noise and EHF audiometric thresholds.

CONCLUSIONS

Overall, the present study showed that sensitive hearing measures enabled the detection of subtle hearing difficulties in young healthy children. In particular, phonemic discrimination in noise showed associations with hearing. Implications of including sensitive hearing measures in children with DLD are discussed.

Speech perception among school-aged skilled and less skilled readers

This study investigated the relationship between speech perception, phonological processing and reading skills among school-aged children classified as 'skilled' and 'less skilled' readers based on their ability to read words, decode non-words, and comprehend short passages. Three speech perception tasks involving categorization of speech continua differing in voicing, place and manner of articulation were administered and compared to phonological processing skills in phonological awareness, speeded naming and verbal short-term memory. The results obtained suggested that (a) speech categorization among skilled readers differed from that of less skilled readers, (b) speech perception skills were associated with both reading and phonological processing skills among both skilled and less skilled readers, however, (c) a strong association between speeded naming and both word and passage reading skills found among skilled readers was absent among less skilled readers. These results suggested that phonological representations and/or activation may not be as well developed in less skilled readers.

Sequential and non-speech praxic abilities in developmental verbal apraxia

Verbal and non-verbal sequential abilities were compared in a group of 10 children with developmental verbal apraxia. Manual gestures, constructional praxic abilities and non-speech volitional oral movements were also studied. Results indicated that these children were deficient in verbal sequential abilities, both with reference to their non-verbal sequential abilities and to normative data. As a group, the children did not present manual-gestural or constructional apraxias, nor oral apraxias for single non-speech volitional movements. However, most had difficulty with sequences of non-speech volitional oral movements.

Grammatical impairment in developmental aphasia

The language production of a 23 year old patient with developmental aphasia caused by birth injury was analyzed in detail within the framework of Chomsky's generative grammar. It was shown that different stages of grammatical development occur simultaneously, without the predominance of those grammatical forms which are identical with or close to adult grammar. Thus the language of this patient with developmental aphasia is quite comparable to the language of children from 3 to 6, and shares many features with grammatical impairment well known from agrammatism and paragrammatism in adult aphasia. It was suggested that in developmental aphasia incomplete linguistic generalizations are related to an incomplete maturation of inhibitory functions during language acquisition, whereas in adult aphasia comparable forms of less advanced grammars are set free by dissolution of function.

Oral-movement abilities and articulatory characteristics of brain-injured adults

We compared the performance of 28 brain-injured adults who displayed articulation problems with that of 28 adults with no history of brain-injury on tests of isolated oral movement and oral-motor sequencing. An attempt was made to classify the brain-injured patients by administering an articulation test and employing three criteria for differentiating apraxia of speech from dysarthria: presence of initiation errors, more substitution errors than combined omission and distortion errors, and the presence of islands of error-free production. While the brain-injured group performed significantly worse on the isolated oral-movement and oral-motor sequencing tests than the normal adults, not all brain-injured patients demonstrated difficulty on these tasks. We were able to identify 13 patients who met all three criteria (apraxia of speech), 3 who met none (dysarthria), and 12 who met one or two but not all (mixed apraxia of speech and dysarthria). Isolated oral-movement and oral-motor sequencing deficits were found in all three groups, but no significant differences among groups on these tasks were observed.

The development of infantile autism

An account is given of how research over the last 30 years has led to progress in the delineation of the mechanisms involved in the genesis of the behaviour covered by the term ‘infantile autism’. The validity, nature, and basis of the syndrome are discussed with reference to treatment.