Here’s how the brain reacts when multiple people talk to you

Take a moment, and imagine you just arrived at a friend’s place for your first post-COVID event. To your left is a bunch of old friends you haven’t seen since 2019 (although it feels like 1919), and to your right, another sizable group of non socially distanced people talk, joke, and laugh.

The entire house feels alive with energy, and even in your imagination, the whole living room is abuzz with the sounds of countless conversations overlapping and sonically competing against one another.

How the human brain deals with and processes multiple conversations at once is often called the “cocktail party problem” by scientists. How does the mind know which voice to prioritize or listen to and which to ignore? These questions have proven tough to answer thus far because it isn’t easy to know what’s going on in someone’s head. Where one’s attention is being directed isn’t always terribly obvious. 

Now, a new study just released by Bar-Ilan University has made some major discoveries regarding how the brain reacts to two competing voices. By recording and observing the brain activity of participants as they attempted to listen to one person while simultaneously ignoring another, study authors made a number of discoveries.

First and foremost, researchers set out to determine if background words and phrases are identified in the brain linguistically, or just as “acoustic noise.” 

“Answering this question helps us better understand the capacity and limitations of the human speech-processing system. It also gives insight into how attention helps us deal with the multitude of stimuli in our environments – helping to focus primarily on the task-at-hand, while also monitoring what is happening around us,” says study leader Dr. Elana Zion Golumbic, of Bar-Ilan University’s Gonda (Goldschmied) Multidisciplinary Brain Research Center.

Their work led to the conclusion that background noise or words are indeed processed by the brain on both a linguistic and acoustic level. During loud, overlapping conversations, brain responses were seen in both the auditory and language-related areas of participants’ minds.

Additionally, recorded brain responses to the words of someone being listened to were stronger when they “competed” against the other words not being paid as close attention to. These findings, researchers say, may finally explain why we often have to make a real effort mentally to focus on one speaker in a crowded area. Our minds can only process so much auditory information at one time. In essence, two speakers are competing for a limited amount of “processing resources.”

These findings were made possible thanks to an experiment in which one person spoke into a participant’s left ear, while another person talked into their right ear. In each scenario, subjects were told to try and listen to only one of the speakers.

Beyond just illuminating how your brain deals with a loud party or crowded nightclub on an auditory level, this study holds numerous larger implications regarding how our minds pick and choose what to focus on in more general terms. 

“Tunnel vision” is often thrown around as a casual phrase, but in a way, our minds place all of us in a tunnel 24/7. The brain decides what we see and how we see it. For example, research indicates some of our peripheral vision is actually just being “filled in” by our minds to save time.

A better understanding of the human mind’s “selective attention” potentially opens the door for new strategies and methods to help people focus their attention across a variety of scenarios. 

The full study can be found here, published in eLife.