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Ataxic dysarthria
R D Kent1, J F Kent, J R Duffy
1University of Wisconsin-Madison, 53705-2280, USA. kentray@waisman.wisc.edu
Journal of Speech, Language, and Hearing Research : JSLHR
|November 4, 2000
Summary
Ataxic dysarthria affects speech consistency, with long-term fundamental frequency variability being a key acoustic abnormality. Speaking tasks reveal irregular syllable rates and variable intelligibility, indicating impaired speech motor control.
Area of Science:
- Neurology
- Speech-Language Pathology
- Acoustic Phonetics
Background:
- Ataxic dysarthria is a motor speech disorder characterized by disrupted articulation and prosody.
- Previous research has explored various acoustic and perceptual features, but consistency and task sensitivity remain unclear.
Purpose of the Study:
- To identify consistent acoustic and perceptual features of ataxic dysarthria.
- To determine the most sensitive speaking tasks for assessing the disorder.
- To investigate uniform effects across speech subsystems.
Main Methods:
- Acoustic and perceptual analyses of speech tasks (vowel phonation, syllable repetition, sentence recitation, conversation) from 14 individuals with ataxic dysarthria.
- Multidimensional acoustic measures including fundamental frequency variability, shimmer, jitter, and peak amplitude variation.
- Analysis of syllable alternating motion rate (AMR) and intelligibility in conversational speech.
Main Results:
- Long-term fundamental frequency variability was the most frequent abnormality in sustained vowel phonation.
- Shimmer, peak amplitude variation, and jitter also showed high abnormality rates.
- Syllable alternating motion rate was slow and irregular, with high variability across repetitions, suggesting respiratory and articulatory control issues.
- Articulatory hypometria was not pervasive, as formant-frequency ranges were largely normal during sentence production.
- Conversational intelligibility varied significantly, with some individuals maintaining acoustic contrasts despite deficits.
Conclusions:
- Long-term fundamental frequency variability is a hallmark acoustic feature of ataxic dysarthria.
- Irregular syllable timing and respiratory/articulatory control deficits are evident in tasks like AMR.
- While articulation may be preserved in some aspects, overall speech intelligibility is affected by variable acoustic contrasts and timing irregularities.