Dip at 4000hz in pure Tone audiometry indicates:-
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.
Otosclerosis
Meniere's disease
Noise induced hearing loss
Age related hearing loss
FMGE 2018