there are 6 types of hearing aids available.

IIC is invisible in the canal hearing aid which is custom fit to each person, these hearing aids undetectable to others and it is situated little away from ear drum. 

BTE is behind the ear which is most common style used by my people in the world. name it self says this hearing aid is situated behind the ear.

ITC is in the canal custom aid made after taking impression of individual's ear. face plate of hearing aid is shows in the outer portion of the first bend

CIC is completely in the canal hearing aid which is also a custom made instrument which is partially visible.

ITE is in the ear hearing aid is moulded uniquely for every ear. the outer portion of hearing aid is shown to the world.

RIC is the receiver inthe canal heairng aid where the receiver is placed in the ear , it provides comfortable open it.