A new paper published in the Journal of Neuroscience reveals how the shape of your ears affects what you hear. Scientists found that implanting a small piece of silicone into an external part of the ear altered people’s ability to detect where a sound was coming from. Over time, however, the brain adapted to the new shape and learnt to pinpoint sounds accurately once again.
Régis Trapeau, author of the paper and a neuroscientist at the University of Montreal said the brain’s ability to determine sound has to do with the way sound waves reverberate off external parts of the ear. The researchers conducted a number of experiments using silicone ear moulds, a dome of speakers and an fMRI machine to record the brain’s activity.
Volunteers who had the ear moulds fitted had a number of sounds played around them and indicated where they thought the noises were coming from. After listening without the ear moulds, the difference was clear. “We would put a sound above the participant’s head, and he would say it’s below,” said Dr. Trapeau.
However, when the volunteers had more testing a week later, most saw their scores go back up. Once we know our ear’s shape, we are able to locate sound, said Dr. Trapeau. When the shape of our ears changes, it takes time to adapt to it. The fMRI scanner revealed that the neurons respond less and less as the sounds came from higher locations, indicating that the neurons most likely represent height by the significance of their response.
The researchers hope the study will allow for the creation of better hearing devices.