Monday, March 18, 2013

Reversal of hearing decline with aging.

It is known that life-long musical experience partially offsets age-related neural timing delays. Such delays make it harder to process speech in noisy environments, and hearing aids don't help. (This is one reason I keep giving piano recitals). In a fascinating recent article, Anderson et al. show a partial reversal of these age-related neural timing delays can be partially reversed by cognitive auditory training. Edited from their text (in which the data show the indicated expectation were confirmed):

An auditory training group (n = 35) completed an adaptive computer-based auditory training program that combines bottom-up perceptual discrimination exercises with top-down cognitive demands. The second group (active control; n = 32) participated in a general educational stimulation program that was matched for time and computer use to that of the auditory training group. We recorded auditory brainstem responses to the speech syllable [da] presented in quiet and noise and assessed speech-in-noise perception, short-term memory, and speed of processing before and after 8 wk of training. We expected that auditory training would induce earlier brainstem peak latencies at posttest compared with pretest, and that the effects of noise on response timing would be reduced. Given previously demonstrated cognitive and perceptual gains from both short-term and long-term auditory training, we expected that auditory training would also improve speech-in-noise perception, short-term memory, and speed of processing.
The abstract:
Neural slowing is commonly noted in older adults, with consequences for sensory, motor, and cognitive domains. One of the deleterious effects of neural slowing is impairment of temporal resolution; older adults, therefore, have reduced ability to process the rapid events that characterize speech, especially in noisy environments. Although hearing aids provide increased audibility, they cannot compensate for deficits in auditory temporal processing. Auditory training may provide a strategy to address these deficits. To that end, we evaluated the effects of auditory-based cognitive training on the temporal precision of subcortical processing of speech in noise. After training, older adults exhibited faster neural timing and experienced gains in memory, speed of processing, and speech-in-noise perception, whereas a matched control group showed no changes. Training was also associated with decreased variability of brainstem response peaks, suggesting a decrease in temporal jitter in response to a speech signal. These results demonstrate that auditory-based cognitive training can partially restore age-related deficits in temporal processing in the brain; this plasticity in turn promotes better cognitive and perceptual skills.
By the way, on this topic, Miller has a recent interesting article on the brain basis of the "cocktail party effect', how we single out a single voice in a room full of conversations.

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