A Psychophysical Study of Rate of Continuous Speech Stimuli By Means of Direct Magnitude Estimation Scaling

The psychological scaling procedure of direct magnitude estimation was employed to establish the relationship of measured and perceived rate of continuous speech stimuli. Time-altered recordings of a standard prose passage were prepared with a speech compressor to provide six variable rates: 75, 125, 175, 225, 275, and 325 w.p.m. A total of 30 master tapes were constructed, one for each of the 30 subjects who participated in the study. Each tape included the six variable stimuli and the standard stimulus to be used in each of three experimental sessions. For each session, one standard stimulus (125, 175, or 225 w.p.m.) and a total of three randomized series of six variable stimuli were used. Results of subjects' magnitude estimations indicate that although a linear trend is evident, there is no one-to-one relationship between measured and perceived rate of continuous speech stimuli. Stevens' power function law appears applicable in describing this relationship. Comparisons of the present results with previous findings using different scaling techniques and different stimuli are discussed.