The latest innovation in hearing aid fitting uses small BTE style hearing aids connected to very thin tubes or wires which end in soft plastic tips. This style is termed open fit because it allows greater air flow into the ear canal than custom molded hearing aids. Leaving the canals open allows the wearer to use the areas of good hearing that he/she may have and reduces or eliminates the plugged feeling sometimes associated with hearing aids. This style was originally designed for people with normal hearing in the low frequencies and a significant loss in the high pitches but currently the fitting range has been expanded to include most mild losses into the moderate and sometimes severe hearing loss categories. The industry has been very active in producing variations of this type of product and at least one or two styles are offered by each major company. Below is a summary of the two major categories of open hearing aid fittings.

In the open acoustic style, the output or receiver is contained in the BTE instrument and sound is delivered to the ear through a thin tube. Some standard BTE hearing aids can be modified to the open acoustic style although most fittings use small BTEs designed to be used only as open fits. Open acoustic fittings are most appropriate for people with normal or near normal hearing in the low pitches and a mild to moderate hearing loss in the high tones. Examples include the Widex m series, Phonak Certena and Versata, Oticon Hit, and Starkey OTE.

In contrast to the acoustic style, the receiver-in-the-ear style open fit removes the output or speaker from the body of the hearing aid and places it into the ear canal. The BTE body and receiver are connected by a very thin tube which looks identical to that used in the acoustic system but contains a wire joining the two components. This style is often smaller than the acoustic style yet can fit a greater range of hearing loss. It is currently the more popular of the two styles. Examples inclde the Resound Alero, Widex Passion, Phonak Audeo Smart, Starkey Zon, Oticon Agil, and Siemems Pure.