In the ear hearing aids are small enough to fit inside an ear, although not as small as completely in the ear canal aids. Working parts of the aid are either in a small compartment clipped to the ear mold or inside the molded part itself. They can be visible only when standing face to face with someone. This type of aid is custom made, to fit an individuals ear. It is usually used with mild to severe cases of hearing loss. Feedback, a squealing/whistling caused by sound (particularly high frequency sound) leaking and being amplified again, may be a problem for severe hearing losses. Some modern circuits are able to provide feedback regulation or cancellation to assist with this.
Venting may also cause feedback. A vent is a tube primarily placed to offer pressure equalization. However, different vent styles and sizes can be used to influence and prevent feedback. Traditionally, ITEs have not been recommended for young children because their fit could not be as easily modified as the earmold for a BTE, and thus the aid had to be replaced frequently as the child grew. However, there are new ITEs made from a silicone type material that mitigates the need for costly replacements. ITE hearing aids can be connected wirelessly to FM systems, for instance with a body-worn FM receiver with induction neck-loop which transmits the audio signal from the FM transmitter inductively to the telecoil inside the hearing instrument. These hearing aids are usually more expensive then behind the ear hearing aids because they need more time to be made since they are custom made.