London, Nov 13 : Noise is not the same as noise – and even a quiet environment does not have the same effect as white noise. With a background of continuous white noise, hearing pure sounds becomes even more precise, says a new study.
White noise is a combination of different sound frequencies, which makes a seemingly random soothing sound that can help cover up other noises.
For the study, published in the journal Cell Reports, researchers investigated the neuronal foundation of sound perception and sound discrimination in a challenging sound environment.
“We found that less overlap occurred between populations of neurons during two separate tone representations, as a result, the overall reduction in neuronal activity produced a more distinct tone representation,” said study researcher Tania Rinaldi Barkat from the University of Basel in Switzerland.
The focus was on research into the auditory cortex – the “auditory brain,” that is, the area of the brain that processes acoustic stimuli. The resulting activity patterns stem from measurements in a mouse brain.
As is well known, the distinction between sounds becomes more difficult the closer they are in the frequency spectrum.
Initially, the researchers assumed that additional noise could make such a hearing task even more difficult.
However, the opposite was observed: The team was able to demonstrate that the brain’s ability to distinguish subtle tone differences improved when white noise was added to the background.
Compared to a quiet environment, the noise thus facilitated auditory perception.
The data of the research group showed that white noise significantly inhibited the activity of the nerve cells in the auditory cortex.
Paradoxically, this suppression of the neuronal excitation led to a more precise perception of the pure tones.
To confirm that the auditory cortex and not another area of the brain was responsible for the change in sound perception, the researchers used the light-controlled technique optogenetic.
Their findings could possibly be used to improve auditory perception in situations where sounds are difficult to distinguish.
According to Barkat, it is conceivable that cochlear implants could be stimulated with an effect similar to white noise in order to improve the frequency resolution and thus the hearing result of their users.