How We Identify Single Voices in a Crowd

Illustration for article titled How We Identify Single Voices in a Crowd

There are plenty of human abilities that we take for granted, but which are actually insanely complex. Like picking out a single voice buried amongst the noise of a crowded environment, a problem which has troubled scientists for decades. But now they've worked out how we do it—and it could revolutionize speech recognition technology.

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The phenomenon—sometimes called the cocktail party effect—allows us to pick out the voice of somebody when all around us is noise. Now, a team of scientists from the University of California, San Francisco has performed experiments on patients undergoing brain surgery to discover how that works. The findings appear in this week's issue of Nature.

During the surgeries, a thin sheet of 256 electrodes was applied to the temporal lobe—the auditory cortex of the brain—of the participants in order to record neuronal activity. Post-surgery, patients were played audio tracks with multiple voices, and asked to identify the words uttered by particular speakers while their brain activity was monitored.

The researchers then used software to reconstruct the brain's activity and assess how it varied when the patients were listening out for different speakers. Amazingly, the neural cortex only seems to respond to a single voice at a time when we're concentrating on making it out, effectively shutting out the rest of the acoustic environment which surrounds us. In other words, selective hearing is very much real—we only hear what we want or need to.

While it's a neat insight, the researchers are also hopeful that it could be a useful tool in assessing hearing impairment and attention deficit disorder. Not just that, they also hope to develop devices for decoding the intentions and thoughts from paralyzed patients that cannot communicate.

And then there's one last, and potentially very lucrative, application: voice recognition. One of the major stumbling blocks with Siri and its brethren is their inability to cope in noisy environments. If scientists can get to the bottom of how the temporal lobe itself filters out extraneous noise, consumer technology could make a huge leap forwards. [Nature]

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Image by Brian A Jackson/Shutterstock

DISCUSSION

randompants
randompants

See, I have the exact opposite problem.

I have a very hard time picking out what the person across the table from me (say, in a crowded lunchroom) is saying. This has naturally led to years of annoyed friends leveling accusations that I'm deaf (or at least need to get my hearing checked). The thing is, I can clearly hear (and make out) the conversation someone is having completely across the room, and "background noise" like the clinking of silverware and glassware is deafening to me.

I have a similar issue when driving/riding in a vehicle (especially in the rain). The tire and road noise is so loud to me that I have to turn the radio up—to levels that totally piss off my poor wife—just to make out what's being said.

Is there such a thing as audio dyslexia? Is this common, or am I alone in my instability to focus on what I'm trying to hear?