Speech comprehension in older adults. Limited by neuronal capacity to process prosodic cues?

Abstract

Age-related hearing loss is not only a condition of the inner ear, but also of the brain, which has to repair the degraded sound input while also incurring structural and functional declines. This ‘central’ hearing loss may therefore manifest itself in various aspects of the brain, such as integrity of its structure, but also in its functional properties. In the last 15 years, relationships between cortical oscillations and speech comprehension have consistently been found. Specifically, oscillations in the theta frequency band (3-7 Hz) have been found to encode slowly changing acoustic speech cues like prosody. Several studies have shown that older adults make strong use of prosodic cues in order to process spoken sentences. Therefore, we tested whether the behavior of cortical theta oscillations as a proxy for older adults’ neuronal capacity to process prosodic cues would predict their ability to understand speech also in a challenging listening environment. Results are compared to those of a previous study and integrated into theoretical accounts of the aging brain and the function of cortical theta oscillations.