Columbia University scientists discovered the brain manages speech differently based on its clarity and our focus on it. They investigated how the brain processes “glimpsed” and “masked” speech. Their results could improve future hearing-aid designs.
We’ve all experienced it — straining to hear a friend at a party or restaurant while the background noise overpowers their voice. Focusing on a single voice takes intense concentration when surrounding noise fights for our attention.
Details
- Researchers recorded neural activity from electrodes implanted in the brains of people during brain surgery.
- Participants were asked to concentrate on one particular voice, which varied in volume.
- At times, the voice would be louder than another voice, known as glimpsed speech, and at other times, it would be quieter than another voice, referred to as masked speech.
Results
- When the voice focused on was louder (glimpsed speech), the brain managed the details of pronunciation in both early- and later-stage auditory processing regions.
- But when the voice was quieter (masked speech), the details of the speech information were managed by the brain only if it was the voice the person was paying attention to.
- The brain also took longer to process masked speech.
“When listening to someone in a noisy place, your brain recovers what you missed when the background noise is too loud. Your brain can also catch bits of speech you aren’t focused on, but only when the person you’re listening to is quiet in comparison.” —Vinay Raghavan, PhD, Columbia University
Why it matters
Knowing how the brain picks voices out from many others in the background could help hearing-aid engineers improve the interpretation of speech masked by noise. Simply amplifying all sounds equally does little to improve the ability to isolate hard-to-hear voices.
The takeaway
Our brains treat clear speech differently from speech washed out by noise. The researchers hypothesize this may be an adaptation to help us cope with background voices so we can zero in on the ones we want to hear.
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