Influence of noise on perception of different types of dysarthric speech

Disturbances in the central nervous system may lead to changes in the speech muscle system, which impact muscle strength, tone, and coordination as well as movement speed, resulting in different types of dysarthria, each impacting respiration, phonation, articulation, resonance, and prosody differentially. Bilateral upper motor neuron damage leads to spastic dysarthria, cerebellar damage ataxic dysarthria, and damage to basal ganglia hypokinetic dysarthria. In estimating the severity of speech impairment, and measuring speech intelligibility, both reading and spontaneous speech samples are routinely used by speech-language pathologists. However, noise levels in acute and rehabilitation hospitals often exceed the World Health Organization guidelines (Busch-Vishniac et al., 2005) which may impact the clinical outcomes. In this study, 100 graduate student clinicians in Speech-Language Pathology measured speech intelligibility and estimated the severity of speech impairment of speech samples produced by three types of dysarthric speakers: spastic, ataxic, and hypokinetic, in two different noise conditions (quiet, and hospital noise). The differential impact of noise on different types of dysarthria is examined, and its implication on clinical outcomes is discussed.