The Recognition of Whispered Speech in Real-Time

Whispered speech offers a unique set of challenges to speech perception and word recognition. The goals of the present study were twofold: First, to determine how listeners recognize whispered speech. Second, to inform major theories of spoken word recognition by considering how recognition changes when major cues to phoneme identity are reduced or largely absent compared with normal voiced speech.

Using eye tracking in the Visual World Paradigm, we examined how listeners recognize whispered speech. After hearing a target word (normal or whispered), participants selected the corresponding image from a display of four-a target (e.g., money), a word that shares sounds with the target at the beginning (cohort competitor, e.g., mother), a word that shares sounds with the target at the end (rhyme competitor, e.g., honey), and a phonologically unrelated word (e.g., whistle). Eye movements to each object were monitored to measure (1) how fast listeners process whispered speech, and (2) how strongly they consider lexical competitors (cohorts and rhymes) as the speech signal unfolds.

Listeners were slower to recognize whispered words. Compared with normal speech, listeners displayed slower reaction times to click the target image, were slower to fixate the target, and fixated the target less overall. Further, we found clear evidence that the dynamics of lexical competition are altered during whispered speech recognition. Relative to normal speech, words that overlapped with the target at the beginning (cohorts) displayed slower, reduced, and delayed activation, whereas words that overlapped with the target at the end (rhymes) exhibited faster, more robust, and longer lasting activation.

When listeners are confronted with whispered speech, they engage in a "wait-and-see" approach. Listeners delay lexical access, and by the time they begin to consider what word they are hearing, the beginning of the word has largely come and gone, and activation for cohorts is reduced. However, delays in lexical access actually increase consideration of rhyme competitors; the delay pushes lexical activation to a point later in processing, and the recognition system puts more weight on the word-final overlap between the target and the rhyme.