Fig. 4. The natural course of tinnitus. In phase 1, the tinnitus intensity is below the perception threshold. In phase 2, the occurrence of a stressful event triggers tinnitus perception. In phase 3-a, tinnitus triggers anxiety, which in turn reinforces the perception of tinnitus, leading to a vicious cycle; whereas in phase 3-b, tinnitus does not trigger anxiety, which results in habituation occurring and the perception of tinnitus decreasing. Modified from Guitton. Front Syst Neurosci 2012;6:12.⁴⁴.