The Effects of Intensive Voice Treatment in Mandarin Speakers With Parkinson's Disease: Acoustic and Perceptual Findings.

PURPOSE: This study investigated the effects of intensive voice treatment on subjective and objective measures of speech production in Mandarin speakers with hypokinetic dysarthria. METHOD: Nine Mandarin speakers with hypokinetic dysarthria due to Parkinson's disease received 4 weeks of intensive voice treatment (4 × 60 min per week). The speakers were recorded reading a passage before treatment (PRE), immediately after treatment (POST), and at 6-month follow-up (FU). Listeners (n = 15) rated relative ease of understanding (EOU) of paired speech samples on a visual analogue scale. Acoustic analyses were performed. Changes in EOU, vocal intensity, global and local fundamental frequency (f o) variation, speech rate, and acoustic vowel space area (VSA) were examined. RESULTS: Increases were found in EOU and vocal intensity from PRE to POST and from PRE to FU, with no change found from POST to FU. Speech rate increased from PRE to POST, with limited evidence of an increase from PRE to FU and no change from POST to FU. No changes in global or local f o variation or in VSA were found. CONCLUSIONS: Intensive voice treatment shows promise for improving speech production in Mandarin speakers with hypokinetic dysarthria. Vocal intensity, speech rate, and, crucially, intelligibility, may improve for up to 6 months posttreatment. In contrast, f o variation and VSA may not increase following the treatment. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.19529017.

Vocabulary influences older and younger listeners' processing of dysarthric speech.

This study examined younger (n = 16) and older (n = 16) listeners' processing of dysarthric speech-a naturally occurring form of signal degradation. It aimed to determine how age, hearing acuity, memory, and vocabulary knowledge interacted in speech recognition and lexical segmentation. Listener transcripts were coded for accuracy and pattern of lexical boundary errors. For younger listeners, transcription accuracy was predicted by receptive vocabulary. For older listeners, this same effect existed but was moderated by pure-tone hearing thresholds. While both groups employed syllabic stress cues to inform lexical segmentation, older listeners were less reliant on this perceptual strategy. The results were interpreted to suggest that individuals with larger receptive vocabularies, with their presumed greater language familiarity, were better able to leverage cue redundancies within the speech signal to form lexical hypothesis-leading to an improved ability to comprehend dysarthric speech. This advantage was minimized as hearing thresholds increased. While the differing levels of reliance on stress cues across the listener groups could not be attributed to specific individual differences, it was hypothesized that some combination of larger vocabularies and reduced hearing thresholds in the older participant group led to them prioritize lexical cues as a segmentation frame.

The role of linguistic and indexical information in improved recognition of dysarthric speech.

This investigation examined perceptual learning of dysarthric speech. Forty listeners were randomly assigned to one of two identification training tasks, aimed at highlighting either the linguistic (word identification task) or indexical (speaker identification task) properties of the neurologically degraded signal. Twenty additional listeners served as a control group, passively exposed to the training stimuli. Immediately following exposure to dysarthric speech, all three listener groups completed an identical phrase transcription task. Analysis of listener transcripts revealed remarkably similar intelligibility improvements for listeners trained to attend to either the linguistic or the indexical properties of the signal. Perceptual learning effects were also evaluated with regards to underlying error patterns indicative of segmental and suprasegmental processing. The findings of this study suggest that elements within both the linguistic and indexical properties of the dysarthric signal are learnable and interact to promote improved processing of this type and severity of speech degradation. Thus, the current study extends support for the development of a model of perceptual processing in which the learning of indexical properties is encoded and retained in conjunction with linguistic properties of the signal.

A follow-up investigation into the mechanisms that underlie improved recognition of dysarthric speech.

Differences in perceptual strategies for lexical segmentation of moderate hypokinetic dysarthric speech, apparently related to the conditions of the familiarization procedure, have been previously reported [Borrie et al., Language and Cognitive Processes (2012)]. The current follow-up investigation examined whether this difference was also observed when familiarization stimuli highlighted syllabic strength contrast cues. Forty listeners completed an identical transcription task following familiarization with dysarthric phrases presented under either passive or explicit learning conditions. Lexical boundary error patterns revealed that syllabic strength cues were exploited in both familiarization conditions. Comparisons with data previously reported afford further insight into perceptual learning of dysarthric speech.

Intervention for lateral /s/ using electropalatography (EPG) biofeedback and an intensive motor learning approach: a case report.

BACKGROUND: Visual biofeedback using electropalatography (EPG) has been beneficial in the treatment of some cases of lateral /s/ misarticulation. While EPG intervention is motorically based, studies have not commonly employed a motor learning approach to treatment. Furthermore, treatment success is measured primarily by change to EPG tongue-palate contact patterns and listener ratings conducted by speech-language therapists. Studies have not commonly measured articulatory change without the palate in-situ using acoustic analysis and non-professional listeners. AIMS: To determine if an intensive treatment programme including both visual biofeedback (EPG) and traditional articulation techniques within a motor learning paradigm would result in functional improvement to /s/ articulation in an 11-year-old girl with persistent lateral misarticulation. METHODS & PROCEDURES: Treatment involved 12 sessions of therapist-delivered treatment over 4 weeks followed by a 6-week home programme. Outcomes of the treatment programme were measured primarily using naive listener ratings and acoustic analysis of /s/ spectra. OUTCOMES & RESULTS: Improvements to both the perceptual and spectral characteristics of /s/ articulation occurred following the treatment programme. CONCLUSIONS: The study highlighted the benefit of an intensive approach to intervention incorporating both visual biofeedback and traditional articulation approaches. The inclusion of a 6-week structured home-programme was beneficial and resulted in consolidation of treatment gains.

The use of electropalatography in the assessment and treatment of acquired motor speech disorders in adults: current knowledge and future directions.

Electropalatography (EPG) has been employed to measure speech articulation since the mid-1970s. This technique has predominately been used in experimental phonetic research and in the diagnosis and treatment of articulation disorders in children. However, there is a growing body of research employing EPG to diagnose and treat articulatory impairment associated with acquired motor speech disorder (MSD) in adults. The purpose of this paper was to (1) review the findings of studies pertaining to the assessment and treatment of MSDs in adults using EPG, (2) highlight current methodologies employed, and (3) discuss the potential limitations of EPG in the assessment and treatment of MSDs and examine directions for future applied research and treatment studies.