Spectral Measures of Loudness in Patients with Ataxic Dysarthriag

Dysarthria refers to a group of speech disorders characterized by neuromuscular involvement. This may affect different subsystems of speech like respiration, phonation, articulation and prosody differentially. Ataxic dysarthria is caused due to damage to the cerebellum. Excessive fluctuation in loudness or monoloudness typically characterizes ataxic dysarthria. These characteristics may be different in ataxic dysarthria due to lesions in different cerebellar loci. There is a need to address the spectral measures related to loudness in patients with lesions in different cerebellar loci.Seventeen subjects with ataxic dysarthria due to lesions in different cerebellar loci and matched controls performed an alternating motion rate (AMR) task. The recorded and digitized speech samples were analysed for spectral measures of maximum and minimum intensity. Intensity range was reduced in subjects with left (left superior paravermal, left anteroinferior), superior vermis, right superior paravermal and right anterosuperior lesions compared to normal controls in AMR task. It was comparable to normal controls in subjects with right posterosuperior lesions. Reduced intensity range seems to be because of increase in energy minima and decrease in energy maxima or due to decrease in energy maxima only.