Effects of a noise-induced audiometric notch on tinnitus distress

Noise-induced hearing loss (NIHL) is a widely known occupational health problem. Two initial characteristics of NIHL are audiometric notch and tinnitus. Many studies focus on the relationship between NIHL and either audiometric notch or tinnitus, however an investigation on the link between audiometric notch and tinnitus is still missing. The objective of the current study is to evaluate tinnitus distress in individuals with noise-induced audiometric notch. A group of 11 individuals with a history of noise exposure and sensorineural hearing loss were included. Tinnitus mapping, including location, loudness, pitch and minimal masking level; residual inhibition (RI), tinnitus handicap inventory (THI), and Mini-Tinnitus Questionnaire (TQ 12-T) were performed. Audiometric notch was observed at 6 kHz, being in line with previous studies, in 46% of the participants. However, a significant number of participants (54%) had audiometric notch at 4 kHz. According to THI and TQ 12-T results, noise-induced audiometric notch was associated with moderate tinnitus distress. Additionally, tinnitus pitch was closely correlated to the notch frequency and easily inhibited by the sound.