The importance of the new study, which comes from the University of Basel, is that it should pave the way for a new type of cochlear implant. Despite advances with hearing aids and research into the role of hearing in human communication, there remains considerable gaps in terms of how acoustic signals are perceived and how they are processed to allow a person to comprehend them.
In fact, ten percent of the human population suffers from auditory cortex disorders, yet scientists understand very little about its role in making sense of sounds.
However, one thing that is clear is that the more precisely a human can distinguish sound patterns, then the better their hearing is.
The new research study looks at how the brain attempts to distinguish between relevant and less relevant information under conditions where there is background noise.
White noise
White noise is not the same as other noise; even a quiet environment does not have the same effect as white noise. White noise refers to sounds that mask other sounds that might occur naturally in an environment. The ‘noise’ is produced by combining sounds of all different frequencies together.
This combination is why ‘white’ is used as the descriptor for the sounds, based on the way white light works. White light is composed of all of the different colors (frequencies) of light combined together. In the same way, white noise is a combination of all of the different frequencies of sound – such as 20,000 tones all playing together at the same time.
Sleep aid
Other research suggests that white noise can aid sleep by masking distracting sounds, possibly also providing relief from tinnitus (ringing in ears):
Such is the growing interest with white noise, Spotify even has a white noise playlist.
Research study
The Swiss researchers looked at the auditory cortex, the area of the brain that processes acoustic stimuli. This is part of the auditory system, performing basic and higher functions in hearing, such as possible relations to language switching.
For the study, the brains of mice were examined. This revealed that the way that sounds are distinguished becomes more difficult the closer a given sound is within the frequency spectrum. It had been thought that additional noise makes the hearing task even more difficult. However, the experiments showed that the brain’s ability to distinguish subtle tone differences became better when white noise was added to the background. Hearing was found to be superior under condition of white noise compared with a quiet environment.
The reason for this is because white noise inhibits the activity of the nerve cells in the auditory cortex. The suppression of the nerve cell activity enabled more precise perception of the pure tone to occurs.
Based on these findings it should be possible to engineer cochlear implants that are stimulated with an effect similar to white noise as so to improve the frequency resolution and hence the hearing result of their users.
Research paper
The research is published in the journal Cell Reports. The research paper is titled “White Noise Background Improves Tone Discrimination by Suppressing Cortical Tuning Curves.”
Essential Science
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue.
Last week we looked at new evidence which demonstrates that the key to living longer is to get a good amount of sleep. This research focus is with epigenetics. Here scientists have mapped changes in gene expression in people who died between 60 and 100 years old. The purpose was to understand how changes in gene expression correlated to longevity, with the conclusion that a good sleep boosts life-expectancy.
The previous week we examined a team of virologists who are edging closer to developing a universal flu vaccine, based on an antibody that attaches to a protein. Given that flu viruses require this protein to reproduce in the body, this could provide the basis for a ‘universal’ vaccine.
