Listening: A Work in Progress

Our listening system is quite amazing.

Imagine you are at a party and there is a group of people chatting. You may be talking to one person for a while, and then you may shift your focus to another. You're still standing in the same spot, but you are able to home in on one conversation at a time. While listening in noise may be tough, we are able to tune in to one speaker while the other becomes part of the background sound.  We have known about this for a long time - it's called the "cocktail party effect" and it's one of the cool things about our amazing hearing system.

A similar process is being studied at the University of California at Berkeley. We've all had this experience, too: initially someone's thick accent seems indecipherable, or you can't make out the lyrics of a song.  You listen again and again, and voila!  The meaning of garbled words pops out.

Recent work suggests that the brain is actually retuning itself to perceive speech information. The UC Berkeley neuroscientist have seen this process in action by recording activity from the surface of a person's brain as the words of a previously unintelligible sentence suddenly pops out. The retuning happens in less than a second!

The researcher Chris Holdgraf says "We believe that this tuning shift is what helps you 'hear'  the speech in that noisy signal. The speech actually pops out from the signal." Co-author Frederik Theunissen adds "Something is changing in the auditory cortex to emphasize anything that might be speech-like, and increasing gain for those features," making the speech more audible in noise.

Another co-author Robert Knight adds "It is unbelievable how fast and plastic the brain is. In seconds or less, the electrical activity in the brain changes its response properties to pull out linguistic information."

Hearing in noise is a challenge for all, and especially for those with hearing loss. But, it is exciting to know that our brains do work to direct our attention and facilitate pulling the message out of the noise. And as we continue to listen, a signal that initially unintelligible may well become clear. Listening is literally a work in progress. If you have hearing aids to help catch more sound, be sure to wear them on a full time basis, and keep listening.