Osei-Lah and Yeoh (2010) report the common misconception that high-frequency notches necessarily indicate noise-induced hearing loss (NIHL). The authors evaluated 149 consecutive patients. Full clinical histories with particular respect to noise histories (and related factors) were obtained. Eighty-four (84) females and 65 males participated. The mean age of participants was 45 years. As has been shown in previous studies, some 40 percent of participants had notches that were not attributable to noise (occupational or recreational) or other known risk factors (Note: Osei-Lah and Yeoh deferred to the Coles et al (2000) definition of a high-frequency notch--hearing threshold at 3000 and/or 4000 and/or 6000 Hz, which is at least 10 dB greater than the threshold(s) at 1000 or 2000 Hz, and at 6000 and/or 8000 Hz, respectively).
The authors concluded that high-frequency notch without excessive noise exposure (and without other risk factors) is common and high-frequency notch is not necessarily diagnostic of NIHL. They note that high-frequency notches may occur for many non-NIHL reasons such as secondary to perilymph fistula, ototoxic drugs, head trauma, genetic hearing loss, idiopathic etiologies, and more.
For More Information, References, and Recommendations:
Osei-Lah V, Yeoh, LH. (2010) High Frequency Audiometric Notch: An Outpatient Clinic Survey. International Journal of Audiology 49:95-98.