This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
In noice 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: Ans. is 'd' i.e., 4000 Hz Noise induced hearing loss Exposure to loud noise can lead to permanent hearing threshold shifts. This may happen immediately with extreme exposure (nearby explosion or gunfire), but more commonly occurs slowly over time with repeated exposure to industrial or environmental noise. Patients will often have a typical 4-KHz (4000 Hz) notch (dip at 4000 Hz) in their audiogram called acoustic dip. Auditory effects of noice are :? Auditory fatigue :- at 90 d B and 4000 Hz. Hearing loss Temporary :- At 4000 - 6000 Hz Permanent :- Repeated prolonged exposure to 100 d B or single exposure to 160 d B.