Jan. 20, 2000
Canadian scientists have discovered an area of the brain that has evolved specifically to respond to the sounds of voices, much as other areas of the brain specialize in recognizing faces.
The research, published in today's Nature, also suggests that the area of the brain may be a fundamental processor that has evolved for sound in a wide variety of animals using vocalization in their everyday lives.
Pascal Belin of the McConnel Brain Imaging Centre at McGill University in Montreal says the structure is specialized for recognizing many vocal sounds, not just speech.
"Here, we are talking voice, not speech. This is important because the voice carries a lot of information that is distinct from words," Belin says.
The adage "It's not what you say but how you say it" may best describe Belin's finding.
The study was conducted using functional magnetic resonance imaging, which makes finely detailed images of brain structures and shows which ones are more active than others. Volunteers listened to a variety of sounds. They included voices, scrambled white noise, natural sounds and mechanical sounds.
The images revealed regions on both sides of the brain responding to the sounds. The regions extended from the temporal lobes along a line above the ears. That area is called the superior temporal sulcus.
Voice recognition in humans and recognition of vocalizations in animals have played a vital role in survival. Because the structure is not specific to speech, Belin says, it is likely to be found in other species.
Evidence exists from research in non-human primates.
Research shows that mother macaques recognize the voices of their infants when played over a speaker. Other mothers present in the same room will recognize the voice of the infant as belonging to a specific female.
Animals also must be able to recognize the sounds of prey and predators.
Belin says it would be fascinating to extend the work to non-human primates to show whether nature employs the same brain structure for vocal recognition and sound interpretation among many species.
Aside from the important evolutionary implications, the work could advance voice recognition technology in computers, Belin says.
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