Background:
Brief acoustic tinnitus suppression following sound stimulation is being studied to better understand the mechanisms underlying tinnitus and short-term suppression of the tinnitus perception. In this context, several kinds of filtered or modulated stimuli have been investigated. However, little research was conducted regarding the effect of stimulation length for brief acoustic tinnitus suppression.

Methods:
The aim of the present study was to compare the extent of tinnitus suppression after a 20-minute and a 3-minute acoustic stimulation with an individual best stimulus. Three experimental sessions were completed by 33 participants with chronic subjective tinnitus. In the first two sessions, eight different individualized, filtered, and/or amplitude-modulated stimuli were presented for 3 min each. For each participant, the stimulus which induced the strongest tinnitus loudness suppression (measured with a numeric rating scale in percent compared to baseline loudness) was chosen and then applied for 20 min in a third session.

Results:
On a group level, no significant difference in tinnitus loudness suppression comparing the 3-minute and the 20-minute acoustic stimulation using the individual best stimulus was observed. However, individual response patterns revealed great diversity as 12 participants showed better suppression after the 20-minute stimulation,12 experienced worse tinnitus suppression and for 9 participants no distinct change was evident compared to 3-minute acoustic stimulation.

Conclusions:
Future research should try to characterize the subgroup of tinnitus patients that profits from prolonged acoustic stimulation and search for optimized simulation durations.