Our brains have an "auto-correct" feature that we use when re-interpreting (重新解释) ambiguous sounds according to new research. The study sheds light on how the brain uses information gathered after the discovering of an initial sound to aid speech comprehension. The findings point to new ways we use information and context to aid in speech comprehension.
"What a person thinks they hear does not always match the actual signals that reach the ear, " explains lead author Laura Gwilliams. "This is because the brain re-evaluates the interpretation of a speech sound at the moment each following speech sound is heard in order to update interpretations as necessary, " Gwilliams says.
It's well known that the perception of a speech sound is determined by its surrounding context — in the form of words, sentences and other speech sounds. This plays out in everyday life — when we talk, the actual speech we produce is often ambiguous. For example, when a friend says she has a "dent (凹痕)" in her car, you may hear "tent". Although this kind of ambiguity happens regularly, we, as listeners, are hardly aware of it. "This is because the brain automatically resolves the ambiguity for us — it picks an interpretation and that's what we perceive to hear, " explains Gwilliams. "The way the brain does this is by using the surrounding context to narrow down the possibilities of what the speaker may mean. "
In the study, the researchers sought to understand how the brain uses this following information to adjust our perception of what we initially heard. To do this, they conducted a series of experiments in which the subjects listened to isolated syllables and similarly sounding words. Their results produced three primary findings: The brain's primary auditory cortex (听觉皮层) is sensitive to how ambiguous a speech sound is at just 50 milliseconds after the sound's appearance. The brain "replays" previous speech sounds while interpreting the following ones, suggesting re-evaluation as the rest of the word unfolds. The brain makes commitments to its "best guess" of how to interpret the signal after about half a second.
