Cortical Associates of Speech-in-Noise Perception from Childhood to Adulthood
Gustafson, Samantha Jordan
It is well documented that noise has a detrimental effect on speech processing and that speech-in-noise perception abilities continue to develop into adolescence. However, our understanding of the mechanism by which background noise adversely affects speech perception throughout childhood remains incomplete. This study used sensory (N1) and cognitive (P3) cortical auditory-evoked potentials (CAEPs) to investigate how background noise affects different stages of speech processing for listeners of various ages and to describe how sensory and cognitive processes contribute to age-related performance variation on a clinical speech-in-noise perception task. Fifty-eight normal-hearing listeners (age 7-25 years) completed a speech syllable discrimination task in quiet and in background noise (4-talker babble, +15 dB signal-to-noise ratio; SNR) using active (i.e., response required) and passive (i.e., no response required) testing conditions. Results showed that the presence of noise affected the sensory representation of speech to a greater extent than the cognitive processes involved in speech sound discrimination. Listeners of all ages showed changes in N1 amplitude and delays in N1 latency when background noise was present. The magnitude of change to the N1 amplitude was dependent upon age but delays in sensory processing were consistent across all listeners. Delays in P3 latencies were found for all listeners with the presence of noise, with no changes measured for P3 amplitude and no effects of age. Noise-induced delays in cognitive processing were not related with behavioral speech-in-noise perception. Conversely, the age-related improvements in speech-in-noise perception that continue throughout childhood and into adolescence were supported by more robust sensory processing of speech in noise. That is, children and adolescents who showed less N1 amplitude reduction also showed better speech-in-noise perception. This work provides a foundation upon which to build when using CAEPs to examine speech-in-noise perception in children with normal hearing or hearing loss and suggests that theories of the development of speech-in-noise perception should consider the role that sensory encoding plays in the successful perception of speech in noise.