Production and Perception of Clear Speech

"Clear Speech" is a distinct speaking style that talkers adopt when the listener has speech perception difficulties due to a hearing loss, background noise, or a different native language. To the extent that clear speech is more intelligible than conversational speech, an acoustic-phonetic comparison of these two speaking styles provides unique information about factors that affect speech intelligibility. This project is driven by the general hypothesis that naturally produced clear speech reflects an interaction of universal, auditory-perceptual factors, which serve to enhance the overall acoustic salience of the speech signal, and language-specific structural factors, which serve to enhance the realization of phonologically important contrasts.

Two important predictions of this hypothesis are:

(a) clear speech production will show predictable and systematic similarities and differences across languages

(b) the intelligibility benefit of naturally produced clear speech will be greater for listeners with well-entrenched knowledge of the sound structure of the target language than for listeners with limited experience with the sound structure of the target language.

In order to test these predictions we compare clear speech production across languages with very different sound structures (English vs. Spanish vs. Croatian) and we compare clear speech perception across listeners that vary with respect to their experience with the sound structure of the target language (native vs. non-native listeners, adults vs. children).

· Click here for some clear speech samples.

Grant Support

Bradlow, A. R. (Principal Investigator).  Production and perception of clear speech.  National Institute for Deafness & Other Communication Disorders  Grant # DC05794.  Direct costs:$500,000.  Grant period: 7/1/04-6/30/08. 

Publications
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· Smiljanic, R. and Bradlow, A. R. (In press). Stability of temporal contrasts across clear and conversational speech. Journal of Phonetics

· Bradlow, A. R. and Alexander, J. A. (2007). Semantic-contextual and acoustic-phonetic enhancements for English sentence-in-noise recognition by native and non-native listeners. Journal of the Acoustical Society of America, 121(4), 2339-2349.

· Smiljanic, R. and Bradlow, A. R. (2005) Production and perception of clear speech in Croatian and English. Journal of the Acoustical Society of America, 118 (3), 1677-1688.

· Liu, S., Del Rio, E., Bradlow, A. R., and Zeng, F.-G. (2004). Clear speech perception in acoustic and electrical hearing. Journal of the Acoustical Society of America, 116 (4), 2374-2383.

· Bradlow, A. R., Kraus, N., and Hayes, E. (2003). Speaking clearly for learning-impaired children: Sentence perception in noise. Journal of Speech, Language, and Hearing Research, 46, 80-97.

· Bradlow, A. R., and Bent, T. (2002). The clear speech effect for non-native listeners. Journal of the Acoustical Society of America, 112 (1), 272-284.

· Bradlow, A. R. (2002). Confluent talker- and listener-related forces in clear speech production. In Gussenhoven, C. & Warner, N. (Eds.) Laboratory Phonology 7. Berlin & New York: Mouton de Gruyter. Pp. 241-273.

· Bradlow, A. R., Torretta, G. M. and Pisoni, D. B. (1996). Intelligibility of normal speech I: Global and fine-grained acoustic-phonetic talker characteristics. Speech Communication, 20, 255-272.