A team of New York University neuroscientists has identified a part of the brain exclusively devoted¹ to processing speech. Its findings point to the superior temporal sulcus (STS), located in the temporal lobe², and help settle a long-standing debate about role-specific neurological functions. "We now know there is at least one part of the brain that specializes in the processing of speech and doesn't have a role in handling other sounds," explains David Poeppel, the paper's senior author, a professor in NYU's Department of Psychology³ and Center for Neural⁴ Science.

 

The study, which appears in the journal Nature Neuroscience, sought to address a decades-old uncertainty--and dispute--in neural science: are there certain regions of the brain exclusively dedicated⁵ to managing speech, thereby⁶ ignoring other sounds, such as music or animal noises?

 

To address this question, the researchers conducted a series of experiments in which the study's subjects listened to speech as well as to other types of "environmental" sounds that ranged from fireworks to ping pong to dogs barking. 

 

To ensure that the subjects were responding to speech sounds rather than to a language that was already familiar to them, the researchers used recorded German-language words--which none of the subjects understood--rather than English ones. In this way, the method aimed to solely⁷ measure the brain's detection of speech, which involves listening and speaking, rather than language, which involves constructing and understanding sentences.

 

To further disguise the origins of both the speech and environmental sounds, the researchers developed a series of audio "quilts"--sound segments, ranging from 30 to 900 milliseconds, in which words or natural sounds were chopped up and reordered. With this method, the researchers could help ensure that the study's subjects were responding only to audio cues rather than guessing their origins--and thus possibly activating⁸ parts of the brain not relevant to sound detection.

 

During these procedures, the researchers gauged⁹ subjects' neurological responses--in multiple parts of the brain--using functional¹⁰ magnetic resonance¹¹ imaging (fMRI). 

 

The results showed expected activity in response to all types of sounds in the temporal lobe's auditory cortex. However, moving further down in this region--to the STS--the results showed activity only in detecting speech sounds, suggesting that this part of the brain is reserved for spotting the spoken word.

点击收听单词发音