Our ears do an incredible job of translating the sounds around us into information that our brains can understand. It's as automatic as breathing and happens without us really giving the process much thought.
Humans also have "selective hearing", which means that we are able to focus on what we want to hear, while screening out less important background noise.
Voice pitch plays a role in our ability to hear someone in a crowded setting, British researchers say.
This process is called selective attention. It was known that selective attention occurs in a part of the brain called the auditory cortex, which processes speed information. But what triggers it was unclear.
"Humans excel at selectively listening to a target speaker when there are a lot of background noises, such as many competing voices," explained study author Tobias Reichenbach.
"In this din of chatter, the auditory cortex switches into action and with laser focus, processes information that enables us to zone in on one conversation. But how these selective process works has been debated," said Reichenbach, of Imperial College London's bioengineering department.
In experiments, 14 volunteers listened to competing conversations while electrodes were fitted to their heads. The researchers discovered that a group of neurons in the brain's auditory stem play a role in selective attention. The auditory stem is located below the auditory cortex.
The study was published recently in the journal eLife.
Improving hearing aids
Specifically, these neurons respond more to the pitch of the voice of a person someone is trying to listen to than to the pitch of other voices.
"Our study is showing us that the pitch of the speaker's voice we want to focus on is an important cue that is used in the auditory brainstem to focus on a target speaker. This helps us to concentrate on a voice while filtering out all the background noise," Reichenbach explained in a university news release.
This line of research could lead to hearing aids that are better able to filter out background noise, which can be a problem for hearing-impaired people in noisy places.
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