Auditory midbrain

• Younger adults ’ responses were more resistant to the effects of background noise than those of older adults Increased temporal jitter associated with loss of auditory nerve fibers may result in decreased temporal precision, greater noise degradation in older adults • Effects of type of background noise did not differ at the level of midbrain The recording was passive and therefore did not engage top-down modulation of responses for different backgrounds Auditory cortex • Older adults had over-representation of the speech envelope for all conditions compared to young adults, suggesting: Changes in the balance of excitatory and inhibitory neurotransmission, or Increased neural resources (including cognitive functions) are engaged to encode the signal. This increase is especially evident in the correlations with performance on attention tests. • The neural representation of the target speech stream is degraded by loud meaningful nois