New Brain Research Bust Theory About Humans Hearing

A new Macquarie University study explains how the findings could lead to better voice recognition technology as well as more advanced hearing devices. The study has advanced knowledge on how humans determine where sounds are coming from and it could unlock the secret to creating a new generation of more adaptable and efficient hearing devices ranging from hearing aids to smartphones.

The holy grail for audio technologies like hearing aids and implants is to mimic human hearing, including accurately locating the source of sounds, but the grail remains elusive. The current approach to solving this problem is based on a model developed by engineers in the 1940s to explain how humans locate a sound source based on differences of just a few tens of millionths of a second in when the sound reaches each ear.

The model uses the theory that each location in space is represented by a dedicated neuron in the human brain, the only function of which is to determine where a sound is coming from. Its assumptions have been guiding and influencing research – and audio technologies – ever since. The only problem is that there are flaws in this engineering approach.

A new research paper in international journal Current Biology by Macquarie University Hearing researchers, Dr Jaime Undurraga, Dr Robert Luke, Dr Lindsey Van Yper, Dr Jessica Monaghan and Professor David McAlpine, has finally revealed what is really going on. And it seems that, in this regard at least, we are not as different from small mammals like gerbils and guinea pigs as we might think.

The paper’s senior author, Professor McAlpine, first created ripples in the hearing research pond nearly 25 years ago by challenging the engineering model in a paper published in Nature Neuroscience.

His theory was strongly opposed at the time by the old guard, but he continued to gather evidence to support it. He was able to show the old model did not apply to one species after another, even the barn owl, which has always been the poster animal for spatial listening. Proving it in humans however, remained difficult, because it was so much harder to show this process in action in the human brain.

Professor McAlpine and his team have now been able to show that far from having a dedicated array of neurons with each tuned solely to one point in space, our brains are instead processing sounds in the same simplified way as many other mammals.