Archives of Acoustics, 38, 3, pp. 375–381, 2013

Pitch Processing of Speech: Comparison of Psychoacoustic and Electrophysiological Data

Małgorzata WRZOSEK
Institute of Psychology, Adam Mickiewicz University

Institute of Psychology, Adam Mickiewicz University

Honorata HAFKE-DYS
Institute of Acoustics, Adam Mickiewicz University

Agnieszka NOWIK
Department of Biophysics, Poznań University of Medical Sciences

Institute of Acoustics, Adam Mickiewicz University

Institute of Psychology, Cognitive Science Program, Head, Action, Cognition Laboratory, Adam Mickiewicz University

The present study consisted of two experiments. The goal of the first experiment was to establish the just noticeable differences for the fundamental frequency of the vowel /u/ by using the 2AFC method. We obtained the threshold value for 27 cents. This value is larger than the motor reaction values which had been observed in previous experiments (e.g. 9 or 19 cents). The second experiment was intended to provide neurophysiological confirmation of the detection of shifts in a frequency, using event-related potentials (ERPs). We concentrated on the mismatch negativity (MMN) – the component elicited by the change in the pattern of stimuli. Its occurrence is correlated with the discrimination threshold. In our study, MMN was observed for changes greater than 27 cents – shifts of ±50 and 100 cents (effect size – Cohen’s d = 2.259). MMN did not appear for changes of ±10 and 20 cents. The results showed that the values for which motor responses can be observed are indeed lower than those for perceptual thresholds.
Keywords: pitch processing of speech; auditory perception-motor dissociation; mismatch negativity
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