PLASTICITY OF THE AUDITORY SYSTEM IN THE ELDERLY

Lavie L, Attias J, Karni A.

University of Haifa.

Hearing loss is the third chronic most common condition reported by the elderly. Many elderly people face greater difficulties understanding speech than would be expected from their audiograms, particularly in degraded listening situations. At least a part of these perceptual difficulties is attributed to Auditory Processing Disorders (APD). One common phenomenon in APD is a reduced overall performance in dichotic listening tests and an enlarged right ear advantage (REA) for speech, due to enlarged deficit in the left ear (LED). These findings are linked to poor ability to use binaural cues.

Hypothesis:  It is possible to diminish the gap between the dominant ear and the non-dominant ear (as measured with dichotic listening tasks) in the elderly, by means of sequential hearing aids fitting and monaural practice. Training will diminish the LED through plastic changes in the auditory system.

Method: 36 elderly hearing impaired subjects (ages 64-89) divided into 3 groups were fitted with binaural hearing aids as followed:

Two groups (A and B) were fitted sequentially, such that the subjects used one hearing aid monaurally for one month, either in the non-dominant ear (group A) or in the dominant ear (group B) (according to dichotic listening tests). On the second month, these subjects used hearing aids binaurally. In the third group (group C) subjects received binaural hearing aids since day one.

Aural auditory training was applied (7 training sessions, 40 minutes each) during the first month, while the subjects wear their personal hearing aid/s. Thus, when monaural hearing aid mode was applied, the aided ear received a higher intensity input, due to the hearing aid's amplification.

Dichotic listening tests were conducted in the beginning of the study, and several times through the study period.

Results: Fast and significant changes in dichotic listening scores following training and hearing aid/s usage were observed. The changes differed according to the trained (fitted) ear and between monaural and binaural fitting.

E-mail: lavielimor@gmail.com