How does the brain activity influence hearing?

Our world is full of cyclic phenomena. For example, many people experience their attention span changing over the course of a day. Maybe you yourself are more alert in the morning, others more in the afternoon. Bodily functions cyclically change or “oscillate” with environmental rhythms, like light and dark, and this in turn seems to govern our perception and behaviors. One might conclude that we are slaves to our own circadian rhythms, which in turn are slaves to environmental light–dark cycles.

Naturally, our brain activity waxes and wanes. When listening, this oscillation synchronizes to the sounds we are hearing. Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences have found that this influences the way we listen. Hearing abilities also oscillate and depend on the exact timing of one’s brain rhythms. This discovery that sound, brain, and behavior are so intimately coupled will help us to learn more about listening abilities in hearing loss.

A hard-to-prove idea in neuroscience is that such couplings between rhythms in the environment, rhythms in the brain, and our behaviors are also present at much finer time scales. Molly Henry and Jonas Obleser from the Max Planck Research Group “Auditory Cognition” now followed up on this recurrent idea by investigating the listening brain.

This idea holds fascinating implications for the way humans process speech and music: imagine the melodic contour of a human voice or your favorite piece of music going up and down. If your brain becomes coupled to, or “entrained” by, these melodic changes, Henry and Obleser reasoned, then you might also be better prepared to expect fleeting but important sounds occurring in what the voice is saying, for example, a “d” versus a “t.”

The simple “fleeting sound” in the scientists’ experiment was a very short and very hard-to-detect silent gap (about one one-hundredth of a second) embedded in a simplified version of a melodic contour, which slowly and cyclically changed its pitch at a rate of three cycles per second (3 Hz).

The researchers hope to be able to use the brain’s coupling to its acoustic environment as a new measure to study the problems of listeners with hearing loss or people who stutter. If you have any questions about hearing loss or hearing aids contact Hidden Hearing. Working with one of our friendly and professional Hearing Aid Dispensers at Hidden Hearing will ensure that you choose the hearing aid that is best for you and your specific hearing loss. To book a free, no-obligation hearing test, call us today on Free Phone 1800 370 000.

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