Auditory Streaming and Prediction in Tinnitus Sufferers

Objectives: The aim of this study was to determine whether auditory streaming (segregation of incoming sounds into separate sound sources) and the ability to anticipate future auditory events are affected in tinnitus sufferers compared with nontinnitus controls with matched levels of hearing. It was hypothesized that tinnitus would result in abnormal electroencephalography responses to tone deviants and tone omissions compared to controls for frequencies near the pitch of tinnitus, and this should correspond with increased levels of cortical γ and θ oscillatory rhythms. Design: Sixteen individuals with tinnitus (10 men and 6 women; age, 53.44; SD, 12.92 years) and 14 control participants (8 men and 6 women; age, 50.25; SD, 18.54 years) took part in the study. A modified version of the ABA streaming paradigm, with repeating triplet pattern of two frequencies (A and B) presented as A-B-A, was used to examine deviant-related prediction error. Omission-related prediction errors were examined using a modified version of a tone-omission paradigm. Regions of interest were frontocentral, left frontal, right frontal, and temporal lobes. Results: A larger N1c waveform was elicited in the absence of any tone deviation within the left primary auditory cortex of tinnitus participants. No differences were present between groups for omissions. The only difference in oscillatory band activity between the two groups in this study was in response to tones 7 semitones different from tinnitus pitch, with significantly lower β-2 band activity present for the tinnitus group, correlating most with activity within the right inferior occipital gyrus. Conclusions: The findings from this study imply that cortical-level auditory stream segregation is altered among individuals with tinnitus. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and text of this article on the journal’s Web site (www.ear-hearing.com). ACKNOWLEDGMENTS: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Deafness Research Foundation New Zealand PhD Scholarship. The authors have no conflicts of interest to disclose. Received August 2, 2016; accepted April 5, 2018. Address for correspondence: Grant D. Searchfield, Section of Audiology, School of Population Health, University of Auckland, Private Bag 92019, Auckland, New Zealand. E-mail: g.searchfield@auckland.ac.nz Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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