The mechanisms that produce tinnitus are not fully understood. From anecdotal evidence we know that there may be a link between mobile phone use and tinnitus. Austrian researchers did an individually matched case-control study to study this relation in 100 patients and 100 controls. They found that mobile phone use up to the index date (onset of tinnitus) on the same side as the tinnitus did not have significantly elevated ORs for regular use and intensity or for cumulative hours of use. But the risk estimate was significantly elevated for prolonged use (≥4 years) of a mobile phone (OR 1.95; CI 1.00 to 3.80). They concluded that mobile phone use should be included in future investigations as a potential risk factor for developing tinnitus.