In-the-ear (ITE) hearing aids
These hearing aids come in plastic cases that fit in the outer ear. They are generally used for mild to severe hearing loss. ITE hearing aids can also be used with other hearing devices. These include the telecoil, a device used to improve sound during phone calls. But the ITE's small size can make it hard to make adjustments. The ITE can also be damaged by ear wax and drainage.
Behind-the-ear (BTE) hearing aids
These hearing aids are worn behind the ear. This type of hearing aid is in a case. It connects to a plastic ear mold inside the outer ear. These are generally used for mild to severe hearing loss. Poorly fitted BTE hearing aids can cause an annoying whistling sound (feedback) in the ear. But all hearing aids can have feedback.
Canal aids fit directly in the ear canal. They come in 2 sizes: in-the-canal (ITC) aid and completely-in-canal (CIC) aid. Canal aids are customized to fit the size and shape of the person's ear canal. They are generally used for mild to moderate hearing loss. Their small size can make them hard to remove and adjust. They can also be damaged by ear wax and drainage.
Body aids are attached to a belt or pocket. They are connected to the ear with a wire. They are mainly used only for profound hearing loss. Or if the other types of hearing aids can't be used.