This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: ENT
Dip at 4000hz in pure Tone audiometry indicates:- 
Select and explain. 
A. Otosclerosis, B. Meniere's disease, C. Noise induced hearing loss, D. Age related hearing loss
C: Noise induced hearing loss
Answer: C: Noise induced hearing loss 
Explanation: 2000Hz / Carha's Notch: seen in otosclerosis (CHL)4000Hz Dip/boiler's notch :seen in noise induced hearing loss (SNHL)Both are seen in bone conduction.