Audiologic Characteristics of Hearing and Tinnitus in Occupational Noise-Induced Hearing Loss

Audiologic Characteristics of Hearing and Tinnitus in
Occupational Noise-Induced Hearing Loss

https://www.advancedotology.org/Content/files/sayilar/110/330-334.pdf

DISCUSSION
Studies of the mechanisms and clinical manifestations of NIHL have shown that during its early stages, hearing loss occurs mainly in the 4–6 kHz region. Hearing loss at these frequencies is likely related to the resonance characteristics of the outer ear and middle ear, the protection function at 2 kHz or the stapedius reflex, and the characteristics of propagating waves starting in the 4 kHz region. Most previous studies of occupational NIHL included relatively few patients. Although the hearing threshold notch is formed at 4 kHz in early-stage patients, gradually affecting the 3-6 kHz range,9 presbycusis in elderly patients results in severe hearing loss at high frequency and slower notch formation.10 As NIHL progresses, hearing is also lost at low frequencies. Both aging and noise contribute to hearing loss, and therefore, it is unclear whether high frequency hearing loss should be regarded as a result of noise.9-11 In our study, the hearing threshold tended to decrease from low to high frequencies in patients with and without tinnitus.

Interesting, as it explains the long term evolution of NIHL.