In order to regain their sense of hearing, many deaf people currently opt for cochlear implants. Such devices are expensive, however, plus they must be surgically installed and they don't work on all forms of hearing loss. That's why a group of researchers at Colorado State University (CSU) are developing an alternative – an electric retainer that transmits spoken words to the user by buzzing their tongue. Cochlear implants start by utilizing one or more external microphones (located adjacent to the ear) to receive sounds. That audio is filtered through a speech processor, which picks out the sounds that are actually human speech. Those speech sounds are then converted into electrical impulses, which are transmitted through the user's skin to a series of electrodes implanted in the cochlea. Those electrodes in turn directly stimulate the user's auditory nerve, delivering sound information to the brain.