Hearing aid in ear. A semi-deep canal hearing aid in a man's ear. This miniaturized hearing aid fits inconspicuously inside the ear canal. The small, transparent cord (lower ear) sticks out into the outer ear, allowing the aid to be pulled out. Hearing aids improve hearing in people with partial deafness. Sound is picked up by a tiny microphone, amplified, and then transmitted into the ear by a tiny speaker. Each hearing aid is fine-tuned to amplify the range of frequencies most needed by the patient.