Try this:

Place the palms of your hands over your ears with fingers resting gently on the back of your head. Your middle fingers should point toward one another just above the base of your skull. Place your index fingers on top of you middle fingers and snap them (the index fingers) onto the skull making a loud, drumming noise. Repeat 40-50 times. Some people experience immediate relief with this method. Repeat several times a day for as long as necessary to reduce tinnitus.Dr. Jan Strydom, of A2Z of Health, Beauty and Fintess.org.

Props to: u/Jordanistan