<prompt> External auditory canal exostosis occurs due to?Repeated instrumentationRecurrent otitis externaWide external auditor meatusRecurrent proplonged cold water exposure  <response>: Ans. is d i.e., Recurrent proplonged cold water exposure Ear canal exostoses are bilateral, usually symmetric multiple bony growths occurring in the medial poion of the external auditory canal. Also known as surfers ear, exostosis is thought to be a reactive process from repeated stimulation by cold water and is much more common than external auditory osteoma 