Hierarchical Encoding of Attended Auditory Objects in Multi-talker Speech Perception

• Published in: Neuron (Cambridge, Mass.) Vol. 104; no. 6; pp. 1195 - 1209.e3
• Main Authors: O’Sullivan, James, Herrero, Jose, Smith, Elliot, Schevon, Catherine, McKhann, Guy M., Sheth, Sameer A., Mehta, Ashesh D., Mesgarani, Nima
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.12.2019; Elsevier Limited
• Subjects: Acoustics; Attention - physiology; Auditory Cortex - physiology; auditory object; cocktail party; Cortex (auditory); Electrodes; encoding; Hearing; Heschl’s gyrus; hierarchical; human auditory cortex; Humans; multi-talker; Neurosurgery; Speech; Speech perception; Speech Perception - physiology; superior temporal gyrus; auditory object; Heschl’s gyrus; hierarchical; human auditory cortex; cocktail party; multi-talker; speech perception; encoding; superior temporal gyrus
• ISSN: 0896-6273; 1097-4199; 1097-4199
• DOI: 10.1016/j.neuron.2019.09.007

Humans can easily focus on one speaker in a multi-talker acoustic environment, but how different areas of the human auditory cortex (AC) represent the acoustic components of mixed speech is unknown. We obtained invasive recordings from the primary and nonprimary AC in neurosurgical patients as they listened to multi-talker speech. We found that neural sites in the primary AC responded to individual speakers in the mixture and were relatively unchanged by attention. In contrast, neural sites in the nonprimary AC were less discerning of individual speakers but selectively represented the attended speaker. Moreover, the encoding of the attended speaker in the nonprimary AC was invariant to the degree of acoustic overlap with the unattended speaker. Finally, this emergent representation of attended speech in the nonprimary AC was linearly predictable from the primary AC responses. Our results reveal the neural computations underlying the hierarchical formation of auditory objects in human AC during multi-talker speech perception. •Mixed speech is encoded differently in primary and nonprimary auditory cortex (AC)•Primary AC selectively represented individual speakers unchanged with attention•Nonprimary AC represented the attended speaker invariant to acoustic overlap•These results show the neural underpinnings of auditory object formation in AC How different areas of the human auditory cortex (AC) represent mixed speech is unclear. O’Sullivan et al. obtained invasive recordings from subjects listening to multi-talker speech. They found that the primary AC represented the individual speakers and was unchanged by attention. In contrast, the nonprimary AC selectively represented the attended speaker, was invariant to the acoustic overlap with unattended speaker, and was linearly predictable from the primary AC. These results reveal the neural underpinnings of the hierarchical formation of auditory objects in human AC.