Date of Degree


Document Type


Degree Name



Speech-Language-Hearing Sciences


Brett A. Martin

Committee Members

Alison Behrman

Joseph J. Montano

Bethany Milner

Subject Categories

Speech and Hearing Science


clear speech, clear speech training, clear speech production, hearing loss, speaking rate, enunciation


Studies have shown that the speech perception of individuals with hearing loss and other perceptual difficulties improves when talkers deliberately use clear speech. Several investigations have reported increased recognition scores of 11 to 34 percentage points for various listener groups in response to naturally produced clear speech. Studies show that clear speech production is highly variable across talkers. Therefore, a consistent method of eliciting clear speech that leads to more unified and consistent production outcomes is needed. Limited evidence suggests that a training program on how to speak clearly may yield greater listener benefit than clear speech produced naturally. The purpose of this study was to evaluate if clear speech training can result in more significant and consistent acoustic changes in speech production than naturally produced clear speech or a control condition of conversational speech. Twelve adult females served as talkers. Their production (in each of the three speaking styles) of sentences taken from the Revised-Speech in Noise (SPIN) test was recorded. Ten randomly selected speech samples consisting of sentences with target words ending with stop consonants were acoustically analyzed. At the sentence level, analyses included the rate of speech (syllables per second), mean and maximum intensity, and duration. Analyses at the target word and final stop consonant levels included mean and maximum intensity and duration. In addition, phonological changes in target words were measured using subjective rater judgments regarding the presence or absence of release of final stop consonants. The data showed a strong effect of speaking style with the largest acoustic changes measured in the trained clear speech. The study demonstrated that with training, individuals make greater acoustic changes to their speech. Previous studies reported natural clear speech to be beneficial for speech perception of listeners with hearing loss (e.g., Picheny et al., 1985, 1986). If trained clear speech can be shown to lead to greater speech perception benefits in adults with hearing loss, it can be recommended to their communication partners. The results have implications regarding the importance of employing clear speech with listeners with hearing loss and for counseling and training strategies in the auditory rehabilitation provided to families of adults with hearing loss.

Keywords: clear speech, clear speech training, clear speech production, older adults, hearing loss, clear speech gain, clear speech benefit, consonant duration, consonant intensity, vowel intensity