Human frequency following responses to iterated rippled noise with positive and negative gain: Differential sensitivity to waveform envelope and temporal fine-structure.

Human frequency following responses to iterated rippled noise with positive and negative gain: Differential sensitivity to waveform envelope and temporal fine-structure.
Hear Res. 2018 Jul 29;367:113-123
Authors: Ananthakrishnan S, Krishnan A
Abstract
The perceived pitch of iterated rippled noise (IRN) with negative gain (IRNn) is an octave lower than that of IRN with positive gain (IRNp). IRNp and IRNn have identical waveform envelopes (ENV), but differing stimulus waveform fine structure (TFS), which likely accounts for this perceived pitch difference. Here, we examine whether differences in the temporal pattern of phase-locked activity reflected in the human brainstem Frequency Following Response (FFR) elicited by IRNp and IRNn can account for the differences in perceived pitch for the two stimuli. FFRs using a single onset polarity were measured in 13 normal-hearing, adult listeners in response to IRNp and IRNn stimuli with 2 ms, and 4 ms delay. Autocorrelation functions (ACFs) and Fast Fourier Transforms (FFTs) were used to evaluate the dominant periodicity and spectral pattern (harmonic spacing) in the phase-locked FFR neural activity. For both delays, the harmonic spacing in the spectra corresponded more strongly with the perceived lowering of pitch from IRNp to IRNn, compared to the ACFs. These results suggest that the FFR elicited by a single polarity stimulus reflects phase-locking to both stimulus ENV and TFS. A post-h...

Source: Hearing Research - July 29, 2018 Category: Audiology Authors: Ananthakrishnan S, Krishnan A Tags: Hear Res Source Type: research