Neural representations of concurrent sounds with overlapping spectra in rat inferior colliculus: Comparisons between temporal-fine structure and envelope

When two sounds with overlapping spectra reach the ears simultaneously, an intriguing question arises: How can the auditory system effectively segregate them? This study delves into this captivating inquiry and reveals an interesting finding: the segregation process manifests in distinct ways for different acoustic components. Our approach involved presenting concurrent yet spatially separated sounds to rats while recording frequency-following responses (FFRs) in the inferior colliculus (IC). Specifically, we focused on extracting responses to two key acoustic components: the fast temporal fine structure (TFS) and the slow envelope (ENV). By examining the stimulus-response coherence, we evaluated how well these components aligned with each sound’s acoustic spectrum. The results unveiled that TFS responses exhibited spatial resolution, displaying strong coherence exclusively with the contralateral sound. In contrast, ENV responses demonstrated spatial mixing, lacking preference for either sound.

Recommended citation: Luo, L., Wang, Q., & Li, L. (2017). Neural representations of concurrent sounds with overlapping spectra in rat inferior colliculus: Comparisons between temporal-fine structure and envelope. Hearing Research, 353, 87-96.