Aging and hearing loss effects on neural speech processing

Abstract

The effects of age-related hearing loss are pervasive, resulting in declines in social, emotional, and cognitive function. As the world becomes a quieter place, the decrease in sensory input from the auditory periphery may trigger homeostatic mechanisms to preserve a stable rate of neural firing at higher levels of the auditory system from brainstem to cortex. For example, decreased inhibitory neurotransmission increases neural excitability, preserving the sensation of loudness for moderate to moderately loud conversational speech levels. However, this change in the balance of excitatory and inhibitory neurotransmission may disrupt the brain’s ability to follow the rapid acoustic changes that are characteristic of running speech. Age-related disruptions in auditory processing of synthesized syllables and naturally-produced words and sentences have been demonstrated using electrophysiology (EEG) and magnetoencephalography (MEG). This presentation will review a series of EEG and MEG studies demonstrating effects of aging and/or hearing loss that vary depending on factors associated with type of hearing loss, stimulus choice, and primary neural source (midbrain versus cortex). Clinical implications for hearing loss management will be discussed. [Work supported by NIH-NIDCD, R21 DC015843-01.]