We know brain activity changes many times over the course of a day. When listening, this oscillation synchronizes to the sounds we are hearing. Not only that, say researchers from the Max Planck Institute for Human Cognitive and Brain Sciences, this oscillation 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 and perhaps people who stutter.
Our world is full of cyclic phenomena; some humans are 'morning people' and some are 'night owls', with different levels of alertness, even over the course of a day. Maybe you yourself are more alert in the morning, others more in the afternoon. Our bodily functions oscillate with environmental rhythms, like light and dark, and this in turn seems to influence our perception and behaviors. We're all beholden to our circadian rhythms, which in turn are slaves to environmental light–dark cycles.
A hard-to-prove idea in neuroscience has been that such couplings between rhythms in the environment, rhythms in the brain, and our behaviors are also present at much finer time scales. 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 these melodic changes, 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” researchers used in their 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).
As the listener'' brain rhythms synchronize with the acoustic stimulus, hearing abilities "oscillate". Credit: Sebastian Willnow
To be able to track each listener’s brain activity on a millisecond basis, Henry and Obleser recorded the electroencephalographic signal from listeners’ scalps. First, the authors demonstrated that every listener’s brain was “dragged along” (this is what entrainment, a French word, literally means) by the slow cyclic changes in melody; listeners’ neural activity waxed and waned. Second, the listeners’ ability to discover the fleeting gaps hidden in the melodic changes was by no means constant over time.
Instead, it also “oscillated” and was governed by the brain’s waxing and waning. The researchers could predict from a listener’s slow brain wave whether or not an upcoming gap would be detected or would slip under the radar.
Why is that? “The slow waxings and wanings of brain activity are called neural oscillations. They regulate our ability to process incoming information”, Molly Henry explains. Jonas Obleser adds that “from these findings, an important conclusion emerges: All acoustic fluctuations we encounter appear to shape our brain’s activity. Apparently, our brain uses these rhythmic fluctuations to be prepared best for processing important upcoming information.”
Citation: Henry, M.J.&Obleser, J., 'Frequency modulation entrains slow neural oscillations and op-timizes human listening behavior', Proceedings of the National Academy of Sciences, Online November 12, 2012.
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Great Earthquakes Doubled In The Most Recent 10 Year Period - What That Means
- Why Climate 'Uncertainty' Is No Excuse For Doing Nothing
- What Americans Fear Most Isn't Ebola Or Terrorism, It's...
- Moderate Pot Use By Adolescents Doesn't Hurt IQ
- Cosmic Rays Jeopardize Deep-Space Astronaut Missions
- Slavery In America: Back In The Headlines
- HPV Vaccine Does Not Cause Multiple Sclerosis
- "Nah. It's not free for the iPhone/iPad/iPod Touch. Apple products usually don't play nice with..."
- "http://www.cdc.gov/vaccinesafety/vaccines/HPV/index.html says no interesting difference in side..."
- "Tommaso, I fully agree with you that for the moment it would be unwise and unjustified to committ..."
- "Chaos, thanks, I couldn't come up with the word. Well, sure. The article really didn't work to..."
- "So many decisions seem to be made by ISEBYs — in someone else’s back yard. ..."
- Anti-conventional ag movement spurs Big Ag to look to organic pesticides
- Can people really inherit memories?
- An end to fat shaming? The 50 year DNA mystery of metabolic dysfunction may soon be solved
- Egg freezing: a smart career move?
- Women carry fetal DNA long after children’s birth
- Despite resistance, China will dominate future of GMOs
- UNC scientists discover hidden subpopulation of melanoma cells
- Teenage self-harm linked to problems in later life
- Unsteady on your feet? Little touches could make all the difference
- Promising blood biomarkers identified for colorectal cancer: Is a screening blood test within reach?
- Studies must be carried out to determine whether exercise slows the onset of type 1 diabetes in children and adults