women in a circle listening to each otherImagine trying to listen to one person at a crowded party. How well can you follow the conversation? Research from a team at Queen’s University led by Dr. Ingrid Johnsrude found that it is not easy for the brain to make sense of a single voice in a crowd. The researchers found that the brain integrates several forms of sensory input to make sense of conversation in a noisy environment and that a specific part of the brain is active when making a dedicated effort to listen. The findings could have applications for people with disorders that affect sensory processing like autism spectrum disorder or attention deficit hyperactivity disorder.

The study’s subjects listened to audio samples while the researchers observed their brain patterns. The subjects listened to samples of both clear and degraded speech and listened both with and without distractions.

Understanding speech in a distracting environment requires focus. The results indicate that in distraction-free environments, people comprehend clear speech effortlessly. However, listening to degraded speech in a distracting environment takes effort. In this context, the brain relies on prior knowledge and other contextual information in addition to speech to derive meaning.

The brain also uses familiarity to its advantage: it is easier to understand a conversation with a familiar voice. Older adults in particular benefit from listening to a familiar voice. In a crowd, older adults find it more difficult to understand new voices, but they comprehend familiar voices just as well as younger adults.

For the brain to make sense of speech in a crowd, it uses higher-order linguistic information from multiple brain regions. Sound is first processed in the brain’s auditory cortex, but to comprehend degraded speech, the brain draws on linguistic processing abilities from elsewhere in the brain. The activation of this sequence of brain regions could be a neural indication of attentive listening.

This research was presented at the 8th Annual Meeting of the Canadian Association for Neuroscience in Montreal Canada.

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