Feature analysis of segmental errors in children with phonological disorders

Past tense productivity in Dutch children with and without SLI: the role of morphophonology and frequency

This study focuses on morphophonology and frequency in past tense production. It was assessed whether Dutch five- and seven-year-old typically developing (TD) children and eight-year-old children with specific language impairment (SLI) produce the correct allomorph in regular, irregular, and novel past tense formation. Type frequency of the allomorph, token frequency and phonotactic probability (PP) of the novel verb form are considered. The results showed all groups were sensitive to the phonological cue. PP did not contribute to past tense inflection of novel verbs in any of the groups, but type frequency did in all three groups. Only the seven-year-old typically developing children relied on token frequency for inflection of regulars. The findings point to an important role of phonology and frequency in past tense acquisition for both TD children and children with SLI. We discuss how the SLI performance pattern relates to theories on SLI.

Bidirectional perception-production relations in phonological development: evidence from positional neutralization

Many children who neutralize phonemic contrasts in production exhibit diminished perception of the same contrasts. It is usually difficult to determine whether the perception deficit caused the production error, or vice versa; however, the direction of causation has implications for treatment planning. This study examines perception-production relationships in the phenomenon of neutralization in strong position, where children neutralize only in perceptually salient contexts. To test a hypothesis that this phenomenon arises from a child-specific pattern of perceptual sensitivity, a non-word discrimination task was administered to a 4-year-old boy with neutralization in strong position in production. Contrary to the perceptual hypothesis, his discrimination accuracy was greatest for contrasts in initial/strong position, where his production errors occurred. Independent of position, however, his perception of a phonemic contrast he neutralized was decreased relative to other contrasts. This case is argued to constitute evidence that a primary production deficit can cause decreased perceptual ability.

Measuring severity of involvement in speech delay: segmental and whole-word measures

PURPOSE

This study examined whether any of a series of segmental and whole-word measures of articulatory competence captured more of the variance in impressionistic ratings of severity of involvement in speech delay. It also examined whether knowing the age of the child affected severity ratings.

METHOD

Ten very experienced speech-language pathologists rated severity of involvement from conversational speech samples obtained from 17 children with delayed speech. The ratings were then correlated with the candidate measures. The ratings by those who knew the ages of the children were also compared with the ratings by those who did not.

RESULTS

The severity ratings showed considerable variability. Ratings from 6 clinicians who largely agreed with each other (a "tin standard" group) were significantly associated with several of the candidate measures. Clinicians appeared to pay attention to number, type, and consistency of errors when rating severity. They also attended to both segmental and whole-word levels. Knowledge of the children's ages did not appear to affect the ratings.

CONCLUSIONS

The observed variability in the severity ratings raises significant questions about their usefulness. Objective measures such as some of those examined herein offer potential as more valid and reliable severity indexes.

Analysis of distortions in children with and without phonological disorders

PURPOSE

To verify using 4 different tests the incidence of distortions in children with and without phonological disorders.

METHOD

Forty children between 4 and 10.2 years of age, divided into 2 groups: 20 with normal development and 20 with phonological disorders. All children underwent the phonology tests of the Child Language Assessment ABFW and 2 spontaneous speaking tests to assess for phonologic alterations. After recording, the data were printed, analyzed, and classified according to the distortions. Nonparametric (Mann-Whitney) statistical analysis was performed with the significance level being set at P <.05.

RESULTS

The phonological disorder group had significantly more occurrences of distortions in all tests compared to the control group (naming, P = .04; imitation P <.001; spontaneous speaking 1, P = .01; and spontaneous speaking 2, P = .002. The Pearson correlation coefficients of the distortion occurrences among the 4 tests were high.

CONCLUSION

The phonological disorder group presented a greater number of distortions in all tests. The most frequent ones were /s, z, 3/ and the variability found within the phonological disorder group was very high. The children in this group had unstable phonological systems and so presented a high number of different distortions. Regarding the evaluation of the phonologic system, all the tests were good evaluation methods since the correlations between them were high.

Diagnostic criteria of developmental apraxia of speech used by clinical speech-language pathologists

The diagnostic criteria used to identify developmental apraxia of speech (DAS) have been at the center of controversy for decades. Despite the difficulty in determining the characteristics that differentiate DAS from other speech acquisition disorders, many children are identified with this disorder. The current report presents the criteria used by 75 speech-language pathologists to establish a diagnosis of DAS. Although 50 different characteristics were identified, 6 of these characteristics accounted for 51.5% of the responses. These characteristics included inconsistent productions, general oral-motor difficulties, groping, inability to imitate sounds, increasing difficulty with increased utterance length, and poor sequencing of sounds. These results are consistent with the general ambiguity of the diagnostic criteria of DAS and suggest that no single deficit is used among clinicians.

Acoustic and perceptual correlates of stress in nonwords produced by children with suspected developmental apraxia of speech and children with phonological disorder

Previous research (L. Shriberg, D. Aram, & J. Kwiatkowski, 1997b, 1997c) has suggested that accuracy in producing linguistic stress reliably distinguishes between children with suspected developmental apraxia of speech (sDAS) and children with phonological disorder (PD). The current investigation tested this hypothesis by examining acoustic correlates of stress in trochaic (strong-weak) and iambic (weak-strong) nonwords produced by 5 children in each of these 2 groups. Four measures relating to stress production were examined: vowel duration, fundamental frequency (f0) at vowel midpoint, timing of the f0 peak relative to vowel onset, and intensity at vowel midpoint. In addition, perceptual judgments of accuracy of stress production were obtained. No group differences in the production of stress were found; however, listeners judged that the nonword repetitions of children with sDAS matched the target stress contour less often than did the repetitions of children with PD. Multiple regression analyses found that mean vowel duration, as well as the relative duration and relative f0 of stressed and stressless syllables, predicted listeners judgments of stress, although these variables only accounted for a small proportion of variance (21.8%). Thus, children with sDAS were able to produce acoustic differences between stressed tently perceptible to listeners.

Research on speech motor control and its disorders: a review and prospective

This paper reviews issues in speech motor control and a class of communication disorders known as motor speech disorders. Speech motor control refers to the systems and strategies that regulate the production of speech, including the planning and preparation of movements (sometimes called motor programming) and the execution of movement plans to result in muscle contractions and structural displacements. Traditionally, speech motor control is distinguished from phonologic operations, but in some recent phonologic theories, there is a deliberate blurring of the boundaries between phonologic representation and motor functions. Moreover, there is continuing discussion in the literature as to whether a given motor speech disorder (especially apraxia of speech and stuttering) should be understood at the phonologic level, the motoric level, or both of these. The motor speech disorders considered here include: the dysarthrias, apraxia of speech, developmental apraxia of speech, developmental stuttering, acquired (neurogenic and psychogenic) stuttering, and cluttering.