Behind-the-Ear, or BTE hearing aids, are aids that have all of their technology in a casing that sits behind the earlobe. The sound that they pick up are sent into a tube, which travels into either a dome or a mould, and is then released into the ear. Behind the ear hearing aids work for almost any person, but the choice in style and design is influenced by the severity of the hearing loss, the shape of the hearing loss (i.e. is the loss in the high pitched sounds, the low pitched sounds, or is it straight across the frequency range?).