Optimization of the Operant Silent Gap-in-Noise Detection Paradigm in Humans.

Background: In the auditory domain, temporal resolution is the ability to respond to rapid changes in the envelope of a sound over time. Silent gap-in-noise detection tests assess temporal resolution. Whether temporal resolution is impaired in tinnitus and whether those tests are useful for identifying the condition is still debated. We have revisited these questions by assessing the silent gap-in-noise detection performance of human participants.

Methods: Participants were seventy-one young adults with normal hearing, separated into preliminary, tinnitus and matched-control groups. A preliminary group (n = 18) was used to optimise the silent gap-in-noise detection two-alternative forced-choice paradigm by examining the effect of the position and the salience of the gap. Temporal resolution was tested in case-control observational study of tinnitus (n = 20) and matched-control (n = 33) groups using the previously optimized silent gap-in-noise behavioral paradigm. These two groups were also tested using silent gap prepulse inhibition of the auditory startle reflex (GPIAS) and Auditory Brain Responses (ABRs).

Results: In the preliminary group, reducing the predictability and saliency of the silent gap increased detection thresholds and reduced gap detection sensitivity (slope of the psychometric function). In the case-control study, tinnitus participants had higher gap detection thresholds than controls for narrowband noise stimuli centred at 2 and 8 kHz, with no differences in GPIAS or ABRs. In addition, ABR data showed latency differences across the different tinnitus subgroups stratified by subject severity.

Conclusions: Operant silent gap-in-noise detection is impaired in tinnitus when the paradigm is optimized to reduce the predictability and saliency of the silent gap and to avoid the ceiling effect. Our behavioral paradigm can distinguish tinnitus and control groups suggesting that temporal resolution is impaired in tinnitus. However, in young adults with normal hearing, the paradigm is unable to objectively identify tinnitus at the individual level. The GPIAS paradigm was unable to differentiate the tinnitus and control groups, suggesting that operant, as opposed to reflexive, silent gap-in-noise detection is a more sensitive measure for objectively identifying tinnitus.