Absolute Magnitude Scaling of Autophonic Loudness

W Hula, M McNeil, J Durrant, P Doyle

 

It has been hypothesized that individuals with hypokinetic dysarthria resulting from Parkinsonís disease may have impaired autophonic scaling, i.e., the perceived loudness of their own vocal intensity.This impairment in autophonic scaling has been proposed to have its basis in proprioceptive or sensorimotor integration deficits that underlie other movement symptoms of the disease.In this study, absolute magnitude scaling procedures, using vowel, sentence, and line stimuli for cross-modality matching (CMM, a relatively easy task), were used to define the autophonic scale in a group of normal speakers and to predict the slopes and intercepts of CMM functions.The sensory magnitude judgments obtained were well described by Stevenís power law, at both the group- and individual-data levels of analysis.Power function slopes proved to be smaller than those previously reported in the literature.Predictions of CMM functions were upheld, although some individual subjects did demonstrate sizable deviations of observed from predicted values.The results suggest that absolute magnitude scaling of oneís own voice via CMM may be useful for investigating reduced speaking intensity in Parkinsonís disease.