Effects of Temporal Alterations on Speech Intelligibility in Parkinsonian Dysarthria

Abstract

The effect of two types of temporal alterations, paced and synthetic, on the intelligibility of parkinsonian dysarthric speech was investigated. Six speakers with idiopathic Parkinson’s disease served as subjects. Paced temporal alterations were created by slowing each speaker to 60% of his/her habitual speaking rate. The synthetic alterations were created by modifying the habitual rate speech samples using digital signal processing. Three types of synthetic alterations were examined: Pause Altered, Speech Duration Altered, and Pause and Speech Duration Altered. The 60% of habitual speaking rate condition was more intelligible than the synthetic conditions. In addition, none of the synthetic alterations were found to be more intelligible than samples produced at habitual speaking rates. The results suggest that simple alterations of speech signals do not explain the differences in intelligibility that have been observed when parkinsonian dysarthric speakers reduce speaking rates. Reasons for the failure of synthetic alterations to increase speech intelligibility scores are discussed.

Effect of Speaking Rate Manipulations on Acoustic and Perceptual Aspects of the Dysarthria in Amyotrophic Lateral Sclerosis

“…What is needed are additional formal tests of the relationship between voluntary modifications of speaking rate, and measures of speech production and speech intelligibility, at both slower-than-habitual and faster-than-habitual rates. The available demonstrations of increased intelligibility with decreased speaking rate are generally for the cases of speakers with hypokinetic dysarthria and relatively faster-thannormal, habitual speaking rates [18,42] and with ataxic speakers with slower-than-normal speaking rates [43,44]. For the larger majority of dysarthric speakers with slow speaking rates, similar demonstrations have not been published.…”

Acoustic and Intelligibility Characteristics of Sentence Production in Neurogenic Speech Disorders

“…Weismer [19] studied the speech of older PD patients in phrase-level utterances and found their speech timing to be similar to that of young adult speakers but faster than age-appropriate controls. Efforts to study the effect of a slowed speaking rate on the intelligibility of speakers with PD have produced mixed results [7]. So far, little is known about the relationship in PD speakers between speech intelligibility at the sentence level and speech acoustic characteristics.…”

“…Speech intelligibility of dysarthric speakers has been evaluated in several studies using single-word tests [1][2][3][4], however, clinical observations suggest there may be large differences between word and sentence productions in these populations. To date the investigation of sentence intelligibility of dysarthric speech is relatively limited [5][6][7].…”

The Effect of Rate Control on Speech Rate and Intelligibility of Dysarthric Speech

“…Hammen et al [9] examined the effect of three synthetic alterations (pause altered, speech duration altered and pause and speech duration altered) on the intelligibility of dysarthric speech secondary to PD. None of the alterations were found to be more intelligible than samples produced at habitual SRs.…”

“…In addition, some rate reduction methods enable the patient to produce more appropriate breath group units, which may result in appropriate syntactic units [8] . Next to the impact on speech production, reduction of speech rate may also provide the listeners more time to decode the distorted speech signal [9] . These results suggest that rate control might have a positive effect on the intelligibility of dysarthric speech.…”