In order to produce even a short word, the brain sends hundreds of motor commands to the muscles that move the mouth, lips, and tongue. These commands need to be executed with precise timing in order to produce the correct sounds. Similarly, the brain is very sensitive at registering the timing of heard speech because even a small miscalculation can lead to perceiving the wrong sound.
There are also different units of speech that are executed at different time lengths, explains EurekAlert:
For example, phonemes are the shortest, most basic unit of speech and last an average of 30 to 60 milliseconds. By comparison, syllables take longer: 200 to 300 milliseconds. Most whole words are longer still.
In order to understand speech, the brain needs to somehow integrate this rapidly evolving information.
But just where in the brain does such fine perception and integration of timing happen? This is what researchers from Duke University and MIT explored in a recent study published in the journal Nature Neuroscience. By playing speech chunks of varying lengths to participants and recording their brain activity inside an fMRI scanner, the study authors were able to identify an area of the brain called the superior temporal sulcus that is specifically sensitive to the timing of heard speech.