Body worn aids (defunct): Invented by Harvey Fletcher of Bell Laboratories in the early 1930s, they were one of the earliest types of hearing aids, but are now rare. The device included a case, earmold, and cordthe amplifier is contained within the case, which was about the size of a pack of cards.Behind the ear aids (BTE): BTEs are the primary replacement for body worn aids. They also include three parts: a case, an earmold, and a tube in place of a cord. The case sits behind the ear (rather than in a pocket or belt, as with the body-worn aids), and sound can be routed either acoustically or electrically.In the ear aids (ITE): Inserted in the outer ear bowl for mild to severe hearing loss, although feedback can increase with severe hearing loss. ITEs were originally avoided with children because they had to be replaced as the child matured, but some modern ITEs are made of a pseudo-silicone material that makes them a more attractive option.Receiver in the canal/ear (RIC/RITE): Similar to the BTE aid, except that the RIC/RITE speaker is placed in the ear canal, and the tube is replaced by electrical wires. This provides a smoother sound as it avoids the distortion of an acoustic tube. Many users are attracted to this option for the aesthetic appeal, as wellthe entire device is almost invisible.In the canal (ITC), mini canal (MIC), and completely in the canal aids (CIC): Some of the smallest aids, covering up only the bottom half of the ear. Intended for mild to moderate/severe hearing loss, but occlusion is more noticeable for people with good low frequency hearing. These aids are more expensive due to the fact that each one is custom-made.Invisible in canal hearing aids (IIC): As evidenced from the name, this aid cannot be seen as it is fitted deeper into the ear canal. The IIC is custom-made and doesn’t block the ear, as other aids do, allowing for more natural sound collection.Extended wear hearing aids: Traditional hearing aids require daily care, but the extended wear models can go 1-3 months without removal. They attract users who are frequently active, especially those who require protection against moisture.Open-fit/over the ear devices (OTE): Includes a plastic case behind the ear and a thin tube running into the ear canal. This reduces occlusion, but allows low frequency sounds to leak out, making OTEs geared toward moderate-to-severe hearing loss sufferers.Personal programmable/consumer programmable: The user can set their own hearing settings using a personal computer, although users can also request remote adjustment by the manufacturer. They come in many of the above styles.Disposable hearing aids: Hearing aids characterized by their non-replaceable battery. May come in a variety of styles.Bone anchored hearing aids (BAHA): A surgically-implanted prosthetic that sends sound through the skull to the inner ear. The BAHA helps to stimulate the cochlea and can also be used by people with unilateral hearing loss.