# The representation of speech conversations in the human auditory cortex: role of social and semantic factors

## TL;DR

This study explores how the brain processes conversations versus monologues, revealing that social and semantic contexts influence neural activity in the auditory cortex.

## Contribution

The study introduces a novel approach combining social and semantic manipulations to investigate speech comprehension in naturalistic contexts.

## Key findings

- Scrambled sentences increased activity in the left superior temporal sulcus compared to intact conversations.
- Semantic disruption elicited stronger responses in dialogues than monologues within the superior temporal sulcus.
- Multivariate analyses showed better sentence classification in dialogues, highlighting enhanced linguistic encoding in social contexts.

## Abstract

Human social nature has shaped auditory perception, as hearing is essential for navigating social interactions, especially when listening to others’ conversations. While much research has examined how the brain processes isolated words or sentences, far less is known about how broader social and semantic contexts influence speech comprehension. We used 7 T fMRI to examine neural responses while participants listened to two-speaker dialogues versus single-speaker monologues, presented either in intact or sentence-scrambled order. Twenty-four healthy young adults listened to AI-generated five-sentence conversations designed to independently manipulate social (dialogue vs. monologue) and semantic (intact vs. sentence-scrambled) contexts. Whole-brain univariate analyses revealed increased activity for scrambled compared to intact conversations in the left superior temporal sulcus (STS), consistent with predictive-coding models. Although social context alone showed no main effect, an interaction emerged: semantic disruption elicited stronger responses in dialogues than monologues within the STS. Multivariate pattern analyses further revealed higher classification accuracy of individual sentences within dialogues vs. monologues, particularly in the left anterior STS and inferior frontal gyrus, suggesting that social context enhances linguistic encoding. Together, these findings indicate that the left STS integrates both semantic and social information, supporting predictive and context-sensitive mechanisms crucial for real-world verbal communication.