There is now consensus that hierarchical processing is a key organizational aspect of the human cortical auditory system. Challenges for future studies include placing hierarchical organization in the temporal lobe within the broader context of larger networks for auditory and language processing, and clarifying the functional contribution of different parallel auditory processing pathways to comprehension of spoken language under varying degrees of effort.
|(A) Hierarchical processing in the temporal lobe, showing a posterior-anterior gradient in acoustic insensitivity moving away from primary auditory cortex. Posterior and anterior regions of STS discussed by Okada et al. (2010) are outlined in white. (B) An expanded model of hierarchical processing for speech that includes prefrontal, premotor/motor, and posterior inferotemporal regions.|
Reference: Peelle JE, Johnsrude IS and Davis MH (2010) Hierarchical processing for speech in human auditory cortex and beyond. Front. Hum. Neurosci. 4:51. doi: 10.3389/fnhum.2010.00051