Sudden sensorineural hearing loss (SSHL) is defined as a change in hearing of 30 dB or more in at least three consecutive frequencies within a 72-hour period. Clinically, a lower threshold is used, especially if there are known risk factors. The presenting audiometric findings are typically unilateral and characterized as a low, high, or flat frequency response using audiometric frequencies between 125-8,000 Hz. The uncomfortable loudness levels (ULL) may or may not demonstrate hyperacusis. Tinnitus matching is typically measured at or below 8,000 Hz, particularly for tinnitus caused by noise-induced hearing loss, although tinnitus may occur above this range (Int Arch Otorhinolaryngol. 2016;20[3]:248).
