Evaluation of a cognitive test battery in young and elderly normal-hearing and hearing-impaired persons.

A cognitive test battery sensitive to processes important for speech understanding was developed and investigated. Test stimuli are presented as text or in an auditory or audiovisual modality. The tests investigate phonologic processing and verbal information processing. Four subject groups, young/elderly with normal-hearing and young/elderly with hearing impairment, each including 12 subjects, participated in the study. The only significant effect in the text modality was an age effect in the speed of performance, seen also in the auditory and audiovisual modalities. In the auditory and audiovisual modalities, the effects of hearing status and modality were seen in accuracy parameters. Interactions between hearing status and modality, both in accuracy and in reaction times, show that hearing-impaired subjects have difficulties without visual cues. Performing the test battery in noise made the tasks more difficult, especially in the auditory modality and for the elderly, affecting both accuracy and speed. Test-retest measurements showed learning effects and a modality-dependent variability. The test battery has proven useful in assessing the relative contribution of different input signals and the effects of age, hearing impairment, and visual contribution on functions important for speech processing.