Our ability to focus on one voice in crowds is triggered by voice pitch

October 10, 2017 by Colin Smith, Imperial College London

Scientists have discovered that a group of neurons in the brain's auditory stem help us to tune into specific conversations in a crowded room.

In order to focus on a particular conversation, listeners need to be able to focus on the of the speaker they wish to listen to. This process is called "" and it has been long known by researchers that it happens in the part of the brain called the , which processes speech information.

Selective attention helps the brain to modulate sound information and to prioritise information over the , such as focusing on one conversation above all others in a crowded room. However, what triggers selective attention in the auditory cortex has been debated by scientists.

In a study published today in the journal eLife, the researchers from Imperial College London write how they investigated the structures downstream of the auditory cortex. In particular, they looked at the contribution that the auditory brainstem, which sits below the auditory cortex, makes to the selective attention process.

The experiment

The researchers set up non-invasive experiments with 14 participants who listened to two competing conversations. Electrodes were fitted to the participants' heads and connected to a computer, which relayed the brain readings in the auditory brain stem. Algorithms devised by the team then decoded the information gathered by the electrodes.

When the participants chose to focus on one conversation above the other, neurons in the auditory brainstem responded more to the pitch of the voice that they listened to rather than to the pitch of the voice that they ignored. This suggests that an important aspect of selective attention occurs in the auditory brainstem and the neural signal is then relayed to the auditory cortex, where higher level processing of occurs.

Pitch is the key

Dr Tobias Reichenbach, the lead author from the Department of Bioengineering, said: "Humans excel at selectively listening to a target speaker when there are a lot of background noises, such as many competing voices. 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 . But how these selective process works have been debated.

"Now, 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."

Implications for hearing

The team suggests that their discovery may hold the key to explaining why some people, who do not have hearing problems in the inner ear, still find it difficult to keep track of conversations in large crowds. It could be that the neurons in their auditory brainstem, associated with receiving pitch signals, are not properly activated.

Improving speech recognition technologies

The researchers say their discovery may also help engineers to refine speech recognition technologies such as automated answering machine systems and speech recognition technologies. Currently, these technologies do not function at their optimum level when there is a lot of background noise. The team suggests that if the technology could focus on the pitch of the user's voice, then it may help to make the speech recognition process more accurate in environments with a lot of noise.

Next steps

Now that the researchers have discovered that voice causes a response in the auditory brain stem they want to refine their experiments further. The next stage will involve non-invasive experiments with participants who will listen to several conversations at once so that the team can determine how selective attention works in more complex environments.

Understanding this process in more detail could, for example, help engineers to build better hearing aids that are more adept at filtering out background noise for users, which is currently a challenge for those with hearing impairments in noisy places.

Explore further: Predicting when a sound will occur relies on the brain's motor system

Related Stories

Predicting when a sound will occur relies on the brain's motor system

October 5, 2017
Whether it is dancing or just tapping one foot to the beat, we all experience how auditory signals like music can induce movement. Now new research suggests that motor signals in the brain actually sharpen sound perception, ...

Cognitive hearing aid filters out the noise

August 3, 2017
People who are hearing impaired have a difficult time following a conversation in a multi-speaker environment such as a noisy restaurant or a party. While current hearing aids can suppress background noise, they cannot help ...

Brain 'hears' voices when reading direct speech

July 26, 2011
(Medical Xpress) -- When reading direct quotations, the brain ‘hears’ the voice of the speaker, say scientists.

Electrical stimulation of brain may help people with schizophrenia learn to communicate better

July 13, 2017
UCLA researchers have found that people with schizophrenia were able to more accurately determine whether two auditory tones matched or differed, after receiving a type of electrical brain stimulation. Being able to distinguish ...

The auditory cortex adapts agilely with concentration

May 24, 2012
The birth of sensory perception on the human cerebral cortex is yet to be fully explained. The different areas on the cortex function in cooperation, and no perception is the outcome of only one area working alone. In his ...

Recommended for you

Neural inflammation plays critical role in stress-induced depression

July 19, 2018
A group of Japanese researchers has discovered that neural inflammation caused by the innate immune system plays an unexpectedly important role in stress-induced depression. This insight could potentially lead to the development ...

Paralyzed mice with spinal cord injury made to walk again

July 19, 2018
Most people with spinal cord injury are paralyzed from the injury site down, even when the cord isn't completely severed. Why don't the spared portions of the spinal cord keep working? Researchers at Boston Children's Hospital ...

Scientists uncover the role of a protein in production and survival of myelin-forming cells

July 19, 2018
The nervous system is a complex organ that relies on a variety of biological players to ensure daily function of the human body. Myelin—a membrane produced by specialized glial cells—plays a critical role in protecting ...

Pregnancy history may be tied to Alzheimer's disease

July 18, 2018
A woman's history of pregnancy may affect her risk of Alzheimer's disease decades later, according to a study published in the July 18, 2018, online issue of Neurology, the medical journal of the American Academy of Neurology. ...

Neurons can carry more than one signal at a time

July 18, 2018
Back in the early days of telecommunications, engineers devised a clever way to send multiple telephone calls through a single wire at the same time. Called time-division multiplexing, this technique rapidly switches between ...

Researchers solve mystery of how ALL enters the central nervous system

July 18, 2018
A deadly feature of acute lymphoblastic leukemia (ALL) is its invasion of the central nervous system.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.