To examine the impact of hearing impairment on a listener's ability to process simultaneous spoken messages.
Nine young listeners with bilateral sensorineural hearing loss and nine young listeners with normal hearing participated in this study. Two messages of equal level were presented separately to the two ears. The messages were systematically degraded by adding speech-shaped noise. Listeners performed a single task in which report of one message was required and a dual task in which report of both messages was required.
As the level of the added noise was increased, performance on both single and dual tasks declined. In the dual task, performance on the message reported second was poorer and more sensitive to the noise level than performance on the message reported first. When compared to listeners with normal hearing, listeners with hearing loss showed a larger deficit in recall of the second message than the first. This difference disappeared when performance of the hearing loss group was compared to that of the normal-hearing group at a poorer signal to noise ratio.
A listener's ability to process a secondary message is more sensitive to noise and hearing impairment than the ability to process a primary message. Tasks involving the processing of simultaneous messages may be useful for assessing hearing handicap and the benefits of rehabilitation in realistic listening scenarios.
An experiment was conducted to examine the impact of hearing impairment on the processing of simultaneous sentences. Young listeners, with and without sensorineural hearing loss, heard two simultaneous messages presented separately to the two ears and were required to report keywords from both. Report of the second message was poorer and more sensitive to signal-to-noise ratio than report of the first. Hearing loss resulted in poorer performance overall, but especially on the second message. Divided listening may be a more sensitive measure than selective listening for assessing hearing handicap and the benefits of rehabilitation.
1Hearing Research Center, Boston University, Boston, Massachusetts; 2School of Medical Sciences, University of Sydney, Sydney, Australia; 3National Center for Rehabilitative Auditory Research, Portland, Oregon.
This work was supported by grants from NIDCD and AFOSR; by a University of Sydney Postdoctoral Research Fellowship (to V.B.); and by the Department of Veterans Affairs, Veterans Health Administration, Rehabilitation Research and Development Service (to F.G.).
Portions of this work were presented at the International Congress on Acoustics in Madrid, Spain (September 2007) and the International Hearing Aid Research Conference in California (August 2008).
Address for correspondence: Virginia Best, School of Medical Sciences, Discipline of Physiology F13, University of Sydney, NSW 2006, Australia. E-mail: firstname.lastname@example.org.
Received March 31, 2009; accepted September 25, 2009.