The relationship between tinnitus pitch and hearing sensitivity

Tinnitus is the phantom perception of sounds. No single theory explaining the cause of tinnitus enjoys universal acceptance, however, it is usually associated with hearing loss. The aim of this study was to investigate the relationship between tinnitus pitch and audiometry, minimum masking levels (MML), tinnitus loudness, and distortion product otoacoustic emissions (DPOAE). This was a retrospective analysis of participant's records from the University of Auckland Hearing and Tinnitus Clinic database. The sample consisted of 192 participants with chronic tinnitus (more than 18 months) who had comprehensive tinnitus assessment from March 2008 to January 2011. There were 116 males (mean = 56.5 years, SD = 12.96) and 76 females (mean = 58.7 years, SD = 13.88). Seventy- six percent of participants had a tinnitus pitch C8 kHz. Tinnitus pitch was most often matched to frequencies at which hearing threshold was 40-60 (T50) dBHL. There was a weak but statistically significant positive correlation between tinnitus pitch and T50 (r = 0.15 at p\0.05). No correlation was found between tinnitus pitch and DPOAEs, MML, audiometric edge and worst threshold. The strongest audiometric predictor for tinnitus pitch was the frequency at which threshold was approximately 50 dBHL. We postulate that this may be due to a change from primarily outer hair cell damage to lesions including inner hair cells at these levels of hearing loss.