Chew on this! Hearing device for the mouth!

BACKGROUND:   Hearing loss is rarely sudden, unless you are exposed to an exceptionally loud noise.  Hearing loss happens for many reasons.  Some people lose hearing slowly as they grow older, a condition called presbycusis.  Doctors do not know why presbycusis happens, but they think it seems to run in families.  Exposure to an excessive amount of loud noise can also be a reason for hearing loss.  This condition is known as noise-induced hearing loss.  People in the armed forces, musicians, airport workers, tree cutters, construction workers, and farmers often suffer from this condition.  Loud noises will cause hissing, ringing, or roaring sound in the ears, known as tinnitus.  Also, hearing loss can be caused by bacteria or a virus, head injuries, heart conditions or stroke, tumors, and certain medications.  (Source:

TREATMENT:  Treatment will depend on the specific hearing problem.  Hearing aids are commonly used. They are tiny instruments that are worn in or behind the ear.  They are designed to make things louder.  Personal listening systems help patients hear what they want to hear while eliminating or lowering other noises.  Auditory training systems and loop systems make it easier to hear someone in a crowded room or group setting.  Others, like FM systems and personal amplifiers, are better for one on one conversation.  There are TV listening systems that help the patient listen to the radio and television.  Direct audio input hearing aids can be plugged into TVs, microphones, stereos, auditory trainers, and personal FM systems to help hearing.  There are also telephone amplifying devices, mobile phone amplifying devices, auditorium-type assistive and listening systems.  Cochlear implants can also be used.  (Source:

NEW TECHNOLOGY:  For patients who are deaf in one ear, the SoundBite Hearing System is the world's first non-surgical and removable hearing solution to use the principle of bone conduction to transmit sound via the teeth.  Bone conduction is the transmission of imperceptible sound vibrations through the bones to the inner ear.  Many sounds can be heard through bone conduction already; for example, when teeth chatter, scratching the scalp, and crunching on potato chips. The SoundBite is intended to help patients who are basically deaf in one ear to regain spatial hearing ability.  It consists of an ITM (in-the-mouth) hearing device, that is custom made to fit around the upper and back teeth, and a small BTE, (behind-the-ear), microphone unit.  SoundBite is a bone conduction prosthetic hearing device.  Prosthetic hearing devices produce the perception of sound by replacing the function of the middle ear, cochlea, or auditory nerve.  It will allow the sound to travel via the teeth through the bones and to the functioning cochlea, while bypassing the outer and middle ear entirely.  SoundBite detects sound using a microphone that is placed in an open-fit dome within the ear canal of the damaged ear.  Placing the microphone in the ear canal will allow the SoundBite Hearing System to focus on the natural acoustic benefit provided by the patient's outer ear to capture and direct sound.  Once sound is captured by the microphone, it is processed by the BTE digital audio device.  The BTE transmits sound wirelessly to the removable ITM.  The ITM produces sound vibrations that are conducted through the teeth, through bone, and to the cochlea.  (Source:

Dr. Susan Kelleher, AuD, CCC-A, Audiologist, Department of Otolaryngology, Daniel's Hearing Center at Boston Medical Center, talks about a new non-surgical option for single-sided deafness.

How does the SoundBite work?

Dr. Kelleher: The SoundBite is a device designed for patients who have unilateral single sided deafness. That means that they have no hearing in one ear and essentially normal hearing in the other ear. The sound bite comes with an ITM (in the mouth piece) and a BTE (behind the ear piece). The behind the ear piece goes on the ear that's not functioning. It's just a microphone. The microphone picks up sounds from that side of the head and it sends it to the piece in the mouth, which then vibrates through Bone conduction. The patient hears the sound in their better ear.

But when hearing it, do they think they're hearing it the bad ear?

Dr. Kelleher: Yes, occasionally. A few patients have said that they feel like they're hearing out of their dead ear. It's not anatomically possible, but it's nice that it can give them the feeling of surround sound.

How does it work as far as fitting it on the person?

Dr. Kelleher: To fit it on the person there is a small measurement that is taken of their ear. There's a behind the ear piece that comes with a wire. I just measure their ear for the wire length and then the microphone just sits in their ear. It's very simple. For the in the mouth piece, they see Dr. Bing Liu, our team dentist here at BMC. They get a full mouth evaluation, x-rays, and a dental impression. The device almost looks like a small retainer that goes on their back two molars on the side of the good ear. This device is referred to at the "actuator" and sends the sound from that mouthpiece to the good hearing organ and they hear it in their better ear.

How far away can somebody be that they'll be able to hear them?

Dr. Kelleher: There is not a set distance for which a patient wearing the device can recognize a sound. The device is designed to pick up sounds that a "normal" ear usually hears. In order to function, the ITM has to be in the mouth and the BTE on the ear. The devices are not going to function as a set unless they are within 20 inches of each other.  I'd say overall from patient feedback the range of the microphone is pretty good. If someone were standing maybe five feet to my right, I‘d still be able to recognize that they're talking or that something's going on.

Who are good candidates for that?

Dr. Kelleher: Good candidates are like Mia. Mia doesn't necessarily have complete deafness or a "dead ear" on her right side, but she has impaired word discrimination ability. So if someone were to talk in her right ear, it would be very unclear. Putting a conventional hearing aid on her impaired ear would not be appropriate. The hearing aid will amplify the sound, but it doesn't make it 100% clear. She's a good candidate because her right ear is not good enough for understanding speech, but her left ear is perfectly clear. So, she has normal hearing in one ear and impaired hearing in the other. We have had patients who had acoustic neuromas, which is a tumor on the hearing nerve that causes them to lose their hearing through surgery or to the growth of the tumor, but they have normal hearing in the other ear so they would be a candidate. Also, those with vestibular disorders or balance disorders that have impaired hearing in one ear would be a candidate as well, as long as the hearing in the good ear is near normal. Patients with bilateral hearing loss are not good candidates for this device.

What's the downside to it?

Dr. Kelleher: It takes some time for people to get used to wearing something on their ear and particularly in their mouth. It's not comfortable in the beginning if you're not used to wearing a retainer or something in your mouth, but after a while it just becomes second nature. Just like wearing glasses, you get used to putting them on in the morning taking them off at night. You get used to the feel of the device in your mouth.

Before the sound bite people would have to go through operations. What would they normally have to do if they didn't use a sound bite?

Dr. Kelleher: If they didn't use the SoundBite, there's a type of device called the CROS hearing aid. It basically puts a device in your bad ear, which is just a microphone. Also, it puts a piece in your good ear, which picks up the sound from the microphone. So, a lot of patients didn't like this because they would have two ears "plugged." Their normal hearing ear now has something in it and though it didn't impair the good ear, it didn't make the sound as clear as natural hearing. It was a microphone similar to the sound bite, but instead of sending it through bone conduction (through vibration) it's sending it to another electronic piece that is put in that good ear.

How would you put that in their ear?

Dr. Kelleher: That particular device is a hearing aid. There is no surgery involved, but the downside is plugging up the good ear with a hearing aid or hearing device. The other option is a surgical one.  During surgery, an otolaryngologist drills an abutment behind the ear and on which audiologists fit a hearing device. That's the device that's similar to the microphone that's on the ear in the SoundBite, but that is a surgical procedure. A lot of the patients I see have lost their hearing through surgery and when they hear surgery they're a bit shy to go that route. So, I completely feel for them. A lot of the patients who deferred this device initially left and I didn't hear from them. Once the sound bite came out, I contacted them and they've been fit with the sound bite and love it because there's no surgical component to it.

Can you explain the bone vibration and how it works?

Dr. Kelleher: The bone oscillator or "actuator" in the mouth picks up the sound from the microphone that's on the ear. It sends sounds from the bad ear to the good ear through vibrations. The device vibrates the bones of the skull into the middle ear and it stimulates the good cochlea or hearing organ. So, the person is hearing out of their good hear completely, but in some senses they feel like they're hearing out of their bad ear.

Is it battery operated?

Dr. Kelleher:  Yes, it's a rechargeable battery. The ITM's piece last for about seven hours on average, sometimes eight depending on the environment they are in. The BTE's piece lasts for eighteen hours. They get two ITMs because they last less time than the BTE's. So all the patient does is switch it out after the battery has expired.

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Susan M. Kelleher, AuD, CCC-A


Boston Medical Center

(617) 638-8124