The study claims that the beneficial effects is due to caffeine. If tinnitus is commonly caused by stomach issues, then caffeine is probably protective for the gut. I posted a study some time ago that showed caffeine being protective for IBS, and excessive gut serotonin.
http://www.pbs.org/newshour/rundown/dri ... -tinnitus/
http://www.pbs.org/newshour/rundown/dri ... -tinnitus/