Natalie Lenzen, Au.D., CCC-A
Typically, we hear sounds that travel from the outer ear (pinna and ear canal) to the middle ear. The middle ear consists of tiny bones that move and these bones then vibrate tiny hair cells in the inner ear. However, sometimes there is a problem in the outer or middle ear that prevents sounds from getting to the inner ear. One way to solve this problem is to bypass the outer and middle ear. We can do this because the inner ear is surrounded by bone and we are able to hear sounds through the vibration of the bones in our skull, which in turn vibrates the inner ear and allows us to hear.
auditory osseointegrated system (AOS) is designed to transfer sounds through the bones in our skull to the inner ear.
The auditory osseointegrated system consists of a sound processor and a mechanical vibrator. The sound processor is an external device that picks up sounds using a microphone, processes the sound and then transmits the sound to the vibrator, which in turn oscillates the skull. These vibrations then travel to the inner ear and bypass any problems one may have in the outer and/or middle ear. The AOS system can be attached to the head using a magnet or an abutment. Typically, a surgical procedure is done to implant the AOS system. An example of the sound processor that attaches via an abutment is depicted in Figure 1. For individuals who are not surgical candidates, such as children under 5, the processor attaches to a soft headband that the patient wears on their head.
People who are considered candidates for an auditory osseointegrated system (AOS) are not able to use or benefit from traditional hearing aids. These patients may have a conductive hearing loss (a hearing loss involving the outer or middle ear) or a mixed hearing loss (a hearing loss that affects the outer or middle ear as well as the inner ear). People with single-sided deafness (a complete hearing loss in only one ear) and normal hearing in the opposite ear are also candidates for an AOS.
Research has shown that the use of an AOS for patients with single-sided deafness can improve hearing in noise.1 Studies have also shown that the use of an AOS for patients with conductive hearing loss, mixed hearing loss or single-sided deafness improves quality of life when compared to not using any device.2,3
An audiologist will complete an audiology evaluation assessing how you hear in your outer, middle and inner ear and how you understand speech to see if you meet the criteria for an AOS. You will also see an Ear, Nose, and Throat physician to determine if an AOS is an appropriate option. If you are a candidate, a processor will be programmed for use on a soft headband and a trial period will be conducted. Questionnaires, as well as speech testing with the device, will be completed to assess potential benefit from the device. If you wish to obtain a personal AOS, insurance pre-authorization will be requested.
Figure 1: Example of an AOS. For this AOS, the screw is surgically implanted and is used to hold the external processor. Photo courtesy of Cochlear America.