In noise-induced hearing loss (NIHL), the characteristic notch on pure tone audiometry is seen at:
- A 250 Hz
- B 4000 Hz ✓
- C 2000 Hz
- D 8000 Hz
Correct answer: B. 4000 Hz
Explanation
NIHL produces a characteristic notch at 4000 Hz on pure tone audiometry, with relative preservation of hearing at 2000 Hz and above 6000 Hz. This is because the region of the cochlea responding to 4 kHz (the resonance frequency of the closed ear canal is ~3400 Hz) is metabolically most vulnerable to acoustic trauma. The notch tends to recover partially at 8 kHz in early NIHL. With prolonged exposure, the notch widens.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.