The effects of attention on the phonetic integration of acoustic information

Abstract

The present study investigated the effects of attention on phonetic processing. Thirty‐five synthetic steady‐state vowels varying from /i/ to /I/ were used. The first three formants of each vowel varied in seven equal logarithmic steps from /i/ to /I/ as the duration varied from short to long in five steps (50, 80, 120, 190, and 300 ms). All of the vowel stimuli were presented to subjects under high‐ and low‐attention conditions. Attention was manipulated by requiring that subjects perform a nonspeech distractor task while simultaneously performing a speech identification task, or by requiring that subjects perform a speech identification task only. Phonetic identification of the vowel stimuli was found to vary with the attention condition. When subjects performed the distractor task and the speech task simultaneously, duration became a more important cue to phonetic identity, whereas the effect of formant frequency was reduced. A quantitative model was developed to characterize how the integration of information from the two kinds of cues, formant structure and duration, changed with attention level.