This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
In noise-induced hearing loss, audiogram shows a typical notch at 
Select and explain. 
A. 1000 Hz, B. 2000 Hz, C. 3000 Hz, D. 4000 Hz
D: 4000 Hz
Answer: D: 4000 Hz 
Explanation: Audiogram in NIHL shows a typical notch at 4000kHz, for both air and bone conduction. (Ref: Diseases of EAR, NOSE AND THROAT by PL DHINGRA - 6th Edition)