One ear does not provide adequate hearing in many situations. Patients with severe hearing loss on one side, but normal hearing in the other ear have difficulty understanding speech in background noise (such as group conversations and restaurants) and determining which direction sound comes from. Unilateral deafness can result from viral infections, trauma, acoustic neuromas and other ear tumors and ear surgery.
Until recently, the best available approach for providing help in this situation has been the CROS (contralateral routing of offside signal) hearing aid. This technique utilized hearing aid microphones worn in both ears and routed sound from the deaf ear to the hearing ear. Unfortunately, most patients were unsatisfied with this system. Common complaints include the cosmetic appearance and discomfort of the headband, and the use of a hearing aid mold in the good ear. Most patients felt the benefit from the device is not worth the disadvantages.
The bone-anchored device, now an FDA cleared solution for unilateral deafness, provides a completely unique benefit. The bone-anchored device is placed on the side of the deaf ear, transfers sound through bone-conduction, and stimulates the cochlea of the normal hearing ear. This effectively transmits sounds from the bad side to the normal ear and ultimately results in a sensation of hearing from a deaf ear. Stereo hearing results in improved understanding of speech, especially in background noise and aids in the localization of sound.
The bone-anchored device offers significant advantages to the traditional CROS hearing aid. The device is placed behind the ear leaving the canal open. It is worn under the hair and is not perceptible to others. Because it is held in place by a clip and directly integrated with the skull bone, there is no need for a head band and pressure against the skin of the head. In recent clinical trials patients prefer the sound and speech clarity achieved with the bone-anchored device versus the CROS and versus the unaided condition.