The latest version of the bone-anchored hearing aid, or Baha®, is an excellent alternative to conventional hearing aids for patients with single-sided deafness (SSD), chronic ear infection or congenital conductive hearing loss, said John S. May, M.D., associate professor of surgical sciences-otolaryngology at Wake Forest Baptist.
“It’s pretty amazing,” May said of the Baha, especially for SSD patients, who get “crystal clear” sound in their good ear plus some sense of sound directionality.  Bone anchored hearing aids are designed based on the fact that the cochlea, which perceives vibrations and transmits the auditory signal to the brain, is embedded in the temporal bone in the base of the skull. The skull is an excellent conductor of vibration: a tuning fork touched to the teeth, for example, can be “heard” just as well as sound coming through the air into a normal ear.
The Baha includes a sound processor that snaps onto a titanium post that is surgically anchored in the skull five to six centimeters behind the ear. The processor converts the sound it receives through its microphone into vibrations that are transmitted through the bone to the cochlea in the patient’s good ear. The vibrotactile sensation on their skull on their deaf side gives them a feeling of where the sound came from.
“It’s not perfect,” May said. “It’s not as though they are actually hearing in that (deaf) ear, but it’s the closest thing to it that we have available.”
Bone Anchored Hearing Aids Succeed Where Conventional Aids Fail
 Those suffering from chronic ear infection, with or without mastoid surgery, could benefit from theuse of the bone anchored hearing system. Conventional hearing aids that block the auditory canal can cause drainage and aggravate the infection. Bone anchored hearing aids leave the ear open, decreasing the occurrence of infection and drainage. May said that “people who for whatever reason can’t wear a conventional hearing aid in their ear canal without complications or discomfort” could be candidates for the Baha.
Patients with conductive hearing loss from some congenital malformations, otosclerosis, atresia, or other conditions of the middle or external ear may also benefit from bone anchored hearing aids.  Today’s bone anchored hearing aid sound processors – marketed by Cochlear Corporation – are smaller than an inch square, and come in colors to match hair and flesh tone. Digital circuitry offers excellent sound, and they can be switched from omni directional to directional to emphasize sound from the front and reduce background noise. Some units even have inputs for audio equipment such as MP3 players.
May said the surgery to implant the post takes about one hour and is done under local anesthetic in most cases. The patient is usually healed and ready to wear the processor within 90 days. May, who sees patients from western North Carolina and the three surrounding states, has done more Baha implants than any other clinic in the state. “We do it as efficiently as it can be done,” he said, “and we try to make it as convenient as possible for the patient.” For more information about the Baha system, visit the Baha website or call 336-716-3895. |