Academic journal article Journal of Medical Speech - Language Pathology

Sentence Stress in Ataxic Dysarthria-A Perceptual and Acoustic Study

Academic journal article Journal of Medical Speech - Language Pathology

Sentence Stress in Ataxic Dysarthria-A Perceptual and Acoustic Study

Article excerpt

This study examined how speakers with ataxic dysarthria produce sentence stress find how these findings relate to other measures of speech performance. Ten speakers with ataxia and ten control speakers performed maximum performance, sentence stress, and passage rending tasks. Perceptual analyses established intelligibility levels and accuracy of stress production. Acoustic analyses included [F.sub.0], intensity, and duration measures for sentence stress targets and MPTs, as well as acoustic rhythm measures for the sentence and passage reading tasks. Results showed that 60% of speakers experienced problems in signalling sentence stress irrespective of the severity of their dysarthria. Intensity and duration were most impaired, with [F.sub.0] and pause insertion being used as compensatory strategies. The results highlighted the need for a detailed examination of speaker abilities in a variety of tasks in order to inform selection of the most effective treatment strategies.

Keywords: ataxia; dysarthria; sentence stress; rhythm

INTRODUCTION

The speech problems experienced by speakers with ataxic dysarthria have been widely reported in the literature. Ataxic dysarthria is particularly characterised by rhythmic disturbances due to excess and equal stress, as well as slow rate, articulator distortions, monopitch/loudness and poorly controlled pitch and loudness modulations (Duffy, 2005; Schalling & Hartelius, 2004; Schalling, Hammarberg, & Hartelius, 2007).

Various attempts have been made to quantify the rhythmic disturbances in ataxic dysarthria (Henrich, Lowit, Schalling, & Mennen, 2006; Liss et al., 2009). These measures largely focus on the duration of vowels and consonants. Contrastive stress tasks have also been employed to study how the modulations of pitch, loudness, and duration interact to signal stress in words and sentences. These studies have identified a number of abnormalities such as reduced changes in [F.sub.0], intensity, and duration (Yorkston, Beukelman, Minifie, & Sapir, 1984) as well as different relationships between these three dimensions (Murry, 1983).

Apart from the above reports very few studies have actually been conducted to identify how speakers with ataxic dysarthria signal stress. In addition, no attempts have hitherto been made to relate findings on stress production to quantification of speaker rhythm or other speech parameters. The current study therefore aimed to revisit the production of stress in speakers with ataxic dysarthria and to relate these findings to other measures of speech performance on a more global scale.

METHOD

Participants

Ten speakers with ataxic dysarthria (AT) and ten healthy control (HC) speakers matched for age, gender, and dialectal background participated in the study (see Table 1 for details). Hearing and vision of all participants were normal or corrected-to-normal and they had no significant cognitive deficits. Dysarthria severity was determined from intelligibility scores derived from a passage reading task rated by five trained listeners (see below).

TABLE 1. Participant Details for Speakers with Ataxic Dysarthria.

speaker                age      gender  etiology  % intelligibility
                                                        score

ATA1                   46         M        CA             74

ATA2                   60         F        CA             67

ATA3                   28         M        FA              6

ATA4                   52         F        CA             25

ATA5                   28         F        FA              9

ATA6                   65         F       SCA6            58

ATA7                   72         M        CA             19

ATA8                   51         M        CA             44

ATA9                   56         M       SCA8            82

ATA10                  57         F        FA             80

ATA mean (SD)      51. … 
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