speech

Selective Attention to Speech Occurs primarily ⁢in the Brain’s⁢ Cortex,New Research Finds

Recent research from the ‌University of ⁣Michigan has clarified ‍the neural basis ⁢of⁣ selective attention ⁤-‌ the ability ‍to​ focus on one sound while filtering out others. ⁢Utilizing novel experimental techniques, scientists have found no evidence⁢ that this process involves differential processing of sound at⁢ subcortical levels, specifically within the auditory nerve or ‌brainstem.The findings indicate that selective attention to speech is ⁣largely‌ driven⁢ by activity within the auditory⁤ cortex.

Prior research on selective ⁢attention often ​employed artificial ⁤sounds, ⁣limiting ⁢its real-world applicability. This study, published ⁣in PLOS ⁤Biology (Stoll, T. J., et al. 2025. doi.org/10.1371/journal.pbio.3003407), more closely mimicked a “cocktail party” scenario by having participants listen ‌to segments ⁣from two audiobooks narrated⁣ by different ‌speakers. Researchers measured responses from ‍the auditory nerve, brainstem, and cortex while ‌participants listened to the audiobooks simultaneously, both in the same ear (diotic⁣ listening) and in opposite ears (dichotic listening).

The results consistently​ showed that the​ subcortical auditory‍ system responded to both attended‍ and ignored speech in the same manner. This contrasts with the cortex, which demonstrably “turns ‌up ‌the volume” ⁣on the sound a person‌ is actively focusing‍ on, according ⁢to Ross‌ Maddox, ⁤Ph.D., associate professor ‌of otolaryngology at ⁣the University of⁣ michigan medical school ‍and ⁣senior author of the paper. Statistical analysis further supported the lack of subcortical⁢ effects. A strong attention effect was observed within the cortex, aligning with previous studies.

The research team ⁣acknowledges that a previous study had ‍yielded conflicting results, potentially due to variations⁣ in experimental design. That⁣ earlier research utilized multiple stories per narrator, introducing potential confounding factors ⁤from “uncontrolled acoustic differences.” An ⁤additional experiment conducted‌ as part of this current study confirmed the potential influence ⁤of such design elements.

Researchers emphasize⁢ that the‍ absence of‌ observed subcortical effects does not definitively‍ rule out their existence. It’s possible that subtle ‌subcortical mechanisms, involving neurons currently beyond the scope of‌ measurement, contribute‍ to selective ‍attention.

“What ⁤we’ve shown here is that for ⁣human‌ studies,‌ there is no ⁤subcortical attention effect that can‌ be measured with the tools we have ‍available,”‍ explained Maddox. The‌ team developed new experimental ⁢methods to address the long-standing ⁤debate, and anticipates ⁤that continued technological ‍advancements may allow‍ for more ‍detailed examination‌ of the auditory brain in ⁤the future.

Source: Michigan Medicine – University of ⁣Michigan (https://www.michiganmedicine.org/)