Karen Forrest

Kinematic, acoustic, and perceptual analyses of connected speech produced by Parkinsonian and normal geriatric adults

Acoustic and kinematic analyses, as well as perceptual evaluation, were conducted on the speech of Parkinsonian and normal geriatric adults. As a group, the Parkinsonian speakers had very limited jaw movement compared to the normal geriatrics. For opening gestures, jaw displacements and velocities produced by the Parkinsonian subjects were about half those produced by the normal geriatrics. Lower lip movement amplitude and velocity also were reduced for the Parkinsonian speakers relative to the normal geriatrics, but the magnitude of the reduction was not as great as that seen in the jaw. Lower lip closing velocities expressed as a function of movement amplitude were greater for the Parkinsonian speakers than for the normal geriatrics. This increased velocity of lower lip movement may reflect a difference in the control of lip elevation for the Parkinsonian speakers, an effect that increased with the severity of dysarthria. Acoustically, the Parkinsonian subjects had reduced durations of vocalic segments, reduced formant transitions, and increased voice onset time compared to the normal geriatrics. These effects were greater for the more severe, compared to the milder, dysarthrics and were most apparent in the more complex, vocalic gestures.

Statistical analysis of word-initial /k/ and /t/ produced by normal and phonologically disordered children

The acoustic characteristics of voiceless velar and alveolar stop consonants were investigated for normally articulating and phonologically disordered children using spectral moments. All the disordered children were perceived to produce /t/ for /k/, with /k/ being absent from their phonetic inventories. Approximately 82% of the normally articulating childrens consonants were classified correctly by discriminant function analysis, on the basis of the mean (first moment), skewness (third moment) and kurtosis (fourth moment) derived from the first 40 ms of the VOT interval. When the discriminant function developed for the normally articulating children was applied to the speech of the phonologically disordered group of children, no distinction was made between the velar and alveolar stops. Application of the model to the speech of individual children in the disordered group revealed that one child produced distinct markings to the velar-alveolar contrast. Variability measures of target /t/ and /k/ utteranc...

The effect of substitution patterns on phonological treatment outcomes

It has been suggested that phonological learning in children with articulation disorders is influenced by the variability or consistency of substitutes used for sounds that are excluded from the inventory. This proposal was based on a post-hoc analysis of childrens pre-treatment inventories and substitution patterns, as well as their generalization patterns at the termination of phonological intervention. In the present investigation, an experimental treatment study was conducted as a direct test of a hypothesized relationship between substitution variation and treatment outcomes. Ten children with multiple articulation errors were divided into two groups on the basis of the variability or consistency of their substitutes for sounds that were omitted from their phonetic inventories. The first group (consistent substitute; CS) of children used the same substitute for the omitted sound in all word-positions, whereas children in the second group (variable substitute; VS) varied the substitute within and acr...It has been suggested that phonological learning in children with articulation disorders is influenced by the variability or consistency of substitutes used for sounds that are excluded from the inventory. This proposal was based on a post-hoc analysis of childrens pre-treatment inventories and substitution patterns, as well as their generalization patterns at the termination of phonological intervention. In the present investigation, an experimental treatment study was conducted as a direct test of a hypothesized relationship between substitution variation and treatment outcomes. Ten children with multiple articulation errors were divided into two groups on the basis of the variability or consistency of their substitutes for sounds that were omitted from their phonetic inventories. The first group (consistent substitute; CS) of children used the same substitute for the omitted sound in all word-positions, whereas children in the second group (variable substitute; VS) varied the substitute within and across word positions. The two groups of children were matched, as closely as possible, on variables for age, phonological knowledge, receptive vocabulary, the sound that was chosen for treatment, and its word-position (i.e. either word-initial or word-final position). Traditional treatment techniques were employed so that only the target sound was presented during therapy sessions. Results confirmed the hypothesis in that all children in the CS group learned the treated sound and generalized it to other contexts; by contrast, no child in the VS group evidenced knowledge of the treated sound by the conclusion of the experiment. These results provide further evidence of the importance of category representation for phonological learning and generalization.

Spectral analysis of target-appropriate /t/ and /k/ produced by phonologically disordered and normally articulating children

Previous research (Forrest, Weismer, Hodge, Dinnsen and Elbert, 1990) has shown that some phonologically disordered children differentially mark seemingly homophonous phonemes; however, the resulting contrast may be spectrally distinct from that produced by normally articulating children of the same age. In the present investigation possible sources for these differences between normally articulating and phonologically disordered childrens productions of target-appropriate phonemes were pursued. Spectral characteristics of seemingly correct productions of /t/ and /k/ in word-initial position were analysed for four normally articulating and seven phonologically disordered children to assess the effect of recency of acquisition, depth of knowledge of the contrast and/or the effect of a phonological disorder on accuracy and variability of production. Results revealed that children who had acquired the velar-alveolar contrast more recently, and who had incomplete knowledge of that contrast, produced target-appropriate /t/ and /k/ differently from their normally articulating peers and other phonologically disordered children with greater knowledge of the contrast. Further, the phonologically disordered children with incomplete knowledge of the velar-alveolar contrast were less variable than the other phonologically disordered or normally articulating children in the spectral characteristics across repeated productions. Analysis of the spectral characteristics of word-initial /t/ and /k/ at a later point in time indicated similarities between all speaker groups in the spectral parameters that distinguished the velar from the alveolar stop. However, the stability of these parameters across repeated productions decreased for the phonologically disordered children with greater knowledge of the contrast. These effects are related to motor skill development and found to be consistent with previously demonstrated patterns of skill acquisition.

The Relationship Between Stimulability and Phonological Acquisition in Children With Normally Developing and Disordered Phonologies

The relationship between stimulability and phonological acquisition was investigated in eight children, four with phonological disorders who were aged 3;10 (years;months) to 5;7 and four with norma...

Impact of substitution patterns on phonological learning by misarticulating children

Learning and generalization of treated sounds to different word positions is a desired outcome of intervention in the phonologically disordered childs system. Unfortunately, children do not always learn the sound that is treated; nor do they always demonstrate across-word generalization. One possible explanation for differences in treatment outcome may relate to the pretreatment substitution patterns used by different disordered children. This post-hoc analysis of treatment data examines the effects on sound learning and generalization of consistent versus inconsistent substitutes. With a consistent substitute across-word position (CS), the same phone was used in initial, medial and final position for a phoneme that was not in the childs inventory. An inconsistent substitute was evidenced by a different phone for a target sound in each position of a word (InAP), or even within word position (InWP) for an error sound. Fourteen children with severe phonological disorders were treated on an obstruent in in...

Evaluation of a Combined Treatment Approach for Childhood Apraxia of Speech.

The current study investigated the impact of a dual treatment approach that included stimulability training protocol (STP) paired with a modified core vocabulary treatment (mCVT) on the speech sounds produced by children with CAS. The combined treatment was assessed for changes in consistency and expansion of the phonetic inventories of four participants. The children participated in 20 treatment sessions over the course of 10 weeks. Each session was comprised of 10 minutes of stimulability training and 45 minutes of mCVT that included words that were chosen by the child and his or her parents. The words were restricted to contain at least one complex phoneme that was omitted from the childs inventory. All children evidenced inventory expansion (average of five sounds) and increased percentage consonants correct (PCC; average of 20% increase), and three of the four children evidenced increased consistency in sound use. The effectiveness of STP paired with mCVT is explained by principles of motor and phonological learning.

A comparison of oral motor and production training for children with speech sound disorders.

Despite the many debates about the usefulness of nonspeech oral motor exercises (NSOMEs) in the treatment of speech disorders, few controlled experiments have evaluated their efficacy in the remediation of phonological/articulatory disorders (PADs). More importantly, the relative effect of NSOMEs compared with traditional production treatment (PT) has not been established. The current study employed an alternating treatment design to evaluate changes in production of sounds targeted by NSOMEs and PT in nine children with PAD. Each subject received treatment on two linguistically distinct sounds in which one sound was treated with NSOMEs and the second sound was targeted with PT. The difference in treatment efficacy, measured as the percentage change in target production for NSOMEs versus PT, was compared using a paired T test. Because NSOMEs typically are used to ready a child for subsequent PT, comparison of PT treatment accuracy was made between NSOME-first and PT-first sessions. Results demonstrated a statistically significant effect of treatment type with greater production gains with PT compared with NSOMEs. Further, no facilitative effect of NSOMEs on PT was noted; however, the choice of distinct treatment targets may have contributed to this null effect. Although additional investigation is warranted, the current investigation does not support the efficacy of NSOMEs in the treatment of PAD.

Analysis of Criteria for Graduate Admissions in Speech-Language PathologyPredictive Utility of Application Materials

Evaluations of applicants to most university speech and hearing programs rely on quantitative measures such as undergraduate grade point averages (UGPA) and scores on the aptitude portions of the G...

Listeners' familiarity and perception of an idiosyncratic phonologic pattern.

Idiosyncratic production of [1] for target /i/ (for example, production of the word “less” for “yes”) was observed in a phonologically impaired preschooler. Recordings of his apparently homonymous productions of minimal pairs contrasting /j/ and /l/ were presented in random order to the childs mother and to five adult listeners who were unfamiliar with the child. No difference was seen across the listeners in their ability to identify target /l/ words. The childs mother, however, correctly identified /j/ targets more frequently than did unfamiliar listeners suggesting that familiarity enhances ones ability to decode idiosyncratic phonologic error patterns.