Auditory-cognitive interactions underlying interaural asymmetry in an adult listener: a case study.

OBJECTIVE

Abnormal interaural asymmetry on tests of dichotic listening is commonly observed in individuals suspected of auditory processing disorder (APD). Although a structural basis for the abnormality has been widely accepted, the influence of cognitive variables on the degree of observed asymmetry has gained increasing attention. To study this issue, we manipulated cognitive influences on interaural asymmetry in an adult with the auditory complaints typically associated with APD.

STUDY SAMPLE: A 55 year-old woman with complaints of difficulty understanding speech in noisy environments despite normal audiometric levels.

DESIGN

Several experimental dichotic procedures were administered. Each procedure was characterized by the manipulation of cognitive task demands.

RESULTS

Interaural asymmetry was greatest when the demands on attention and/or memory were maximal. Electrophysiological data revealed interaural asymmetry on later stages of information processing.

CONCLUSIONS

Results are discussed in relation to auditory-specific outcomes on clinical tests for APD.