Figure 14b. Hearing aids. (a) Lateral radiograph of the cervical spine shows a hearing aid with a behind-the-ear compartment containing a battery (arrow), microphone, and amplifier. The ear mold has been removed. (b) Oblique radiograph of the skull shows a right cochlear implant. Receiver/stimulator (arrows) may look like an external hearing aid at radiography. (c) Cranial CT scan of the same patient as in b shows the cochlear implant. The receiver/stimulator (large arrow) lies in a groove cut into the mastoid portion of the temporal bone. The wire leaving the receiver/stimulator (small arrow) passes into the cochlea and forms the electrodes. The metallic portion of the cochlear apparatus is not seen because it lies in a different plane. (Courtesy of Steve Bessen, MD, Las Vegas, Nev.)