Intake recommendations for iodine and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences) [2].
Answer. The ear canal has very delicate skin; even a hair may cause itching in the ear. So no wonder itching or irritation is a common complaint from the hearing aid user who comes in for a follow up visit.
The pinna (outer part of the ear) funnels sound waves into the ear canal. When sound waves reach the eardrum they cause it to vibrate. Vibrations of the eardrum cause the tiny bones in the middle ear to move too. The last of these bones, the stapes, passes on the vibrations to the cochlea.