Clear versus casual consonant identification by hearing-impaired and normal-hearing listeners

ABSTRACT

Hearing-impaired (HI) listeners who benefit from hearing-aid use in quiet often continue to have difficulty understanding speech in noise. Requesting talkers to speak clearly is one strategy to overcome this deficit. Paradoxically, one feature of clear speech is a shift to higher frequencies, which may move speech energy into a frequency range that is inaudible or more distorted for some HI listeners. Casual (or conversational) speech, on the other hand, may shift speech energy into a lower frequency range that is more audible or less distorted. This study examined the intelligibility of 21 amplified, casually- and clearly-spoken, US English coda consonants in nonsense syllables for 10 normal-hearing (NH) and 17 HI listeners. Most clear-speech consonants yielded higher recognition scores as expected. However, certain phonological processes common in casual speech, such as palatalization of higher frequency alveolar into lower frequency postalveolar consonants, generated significantly higher scores than their clear counterparts for some HI listeners in noise. These results have implications for coaching conversational partners of aided HI listeners. For the military, talkers can be instructed how to speak to Service members with hearing loss or in noisy environments.

KEYWORDS:

• Allophones
• casual speech
• clear speech
• consonants
• hearing impairment

Acknowledgements

The authors express our gratitude to Jennie Canan, Julie Cohen, Mary Cord, Lauren Evans, Alice Franklin, Lina Kubli, Stefanie Kuchinsky, Tia McDonald, LaGuinn Sherlock, Daniel Shub, Van Summers, Chelsea Vogel, Therese Walden, Danielle Zion, and the two SLPs for their assistance. This research was supported by the Army Hearing Division. The views expressed in this document are those of the authors and do not necessarily reflect the official policy of the U.S. Department of Defense, Department of the Army, Army Medical Department, or the U.S. Government. Use of trademarked names does not imply endorsement by the U.S. Army but is intended only to assist in the identification of a specific product. A portion of this research was presented in 2012 at the 164th Meeting of the Acoustical Society of America in Kansas City, MO and in 2016 at the 5th Joint Meeting of the Acoustical Society of America and the Acoustical Society of Japan in Honolulu, HI.

Declaration of interest

The authors report no conflict of interest.