|
|
| BAHA sound pocessor |
|
|
| BAHA implant |
|
| Instead of transferring sound energy to the skull at a point behind the ear, the TransEar devce is positioned in the ear canal. |
Are you – or is someone you know – among the more than 50,000 people in the United States who were diagnosed with single sided deafness this year?
Single sided deafness (SSD) is characterized by signifi cant sensorineural hearing loss in one ear and normal hearing for most speech frequencies in the other ear. The onset typically involves rapid
hearing loss, either immediate or over several days. For almost half of the individuals who experience the onset of SSD, hearing will return to normal. When it doesn’t, the almost certain result will be permanent SSD.
Causes of SSD can include viral infections, trauma, acoustic neuromas or other tumors, so it is imperative to be thoroughly evaluated by a medical doctor (preferably an ENT/otolaryngologist) as soon as symptoms present themselves in order to determine if medical treatment is warranted. An audiologist or other licensed hearing healthcare professional can then assist in determining
what types of hearing instruments or prosthetics may ameliorate the condition. In addition to loss of “stereo” hearing, SSD impedes a person’s ability to locate where sound is coming from, reduces speech perception, reduces the ability to perceive how loud a sound is and, in many cases, causes
loss of spatial balance.
Just as important, SSD significantly impacts lifestyle:
Lifestyle Impact of SSD Study by Entific Medical Systems of 437 patient participants in conjunction with the British Acoustic Neuroma Association.
39% increased difficulty working
24% forced to give up work
79% lack of “stereo” hearing
56% difficulty as pedestrian
55% social exclusion
41% difficulty on telephone
19% difficulty driving
Many individuals avoid certain social situations because of their hearing condition. Studies going as far back as 1965 cite a range of emotions related to hearing loss, including confusion, embarrassment, helplessness and annoyance. For children in particular, the impact on education is alarming: two studies published in 1988 in Scandinavian Audiology Supplement showed that 22 percent to 35 percent of children with SSD failed at least one grade (compared to the norm of Hear in 3.5 percent of children).
With so much documentation quantifying the impact of SSD, it’s surprising to learn that the majority of individuals with SSD do not pursue available remedies and instead go through life simply “coping.” Could this be because the options formerly available to them were uncomfortable, ineffective, too expensive or all of the above? Unfortunately, the effects of SSD on a person’s quality of life are often underestimated by professionals, so not everyone is encouraged to pursue a remedy.
The good news is that there are now better options to help individuals in coping with SSD.
For decades, the primary approach to treating SSD involved amplifi cation of sound via air waves, also known as “air conduction.” The newer approach utilizes “bone conduction,” which takes advantage of the ability of the bones in the skull to conduct sound energy (as opposed to merely amplifying sound, which is what air conduction does.)
Today, the three most common remedies for SSD are CROS (Contralateral Routing of Signal) hearing aids, which use air conduction, the Bone Anchored Hearing Aid (BAHA®) and TransEar®, both of which use bone conduction.
CROS aids utilize either behind-the-ear or in-theear hearing aids that are worn in both ears. The aid on the deaf side has a microphone which collects sounds and transmits a signal (either using a wire or wirelessly) to the good ear. The biggest single disadvantage of a CROS aid is that the good ear is either partially or fully occluded (stopped up). CROS hearing aids eliminate the head shadow effect, that is, the effect on hearing when one ear faces a source of sound and the other ear is shielded from it, and to some extent they enhance the ability to locate where sound is coming from. However, this type of aid has a very low acceptance rate of only 10 percent in people who have tried it. The most frequently cited objections are the disadvantage noted above as well as patient dissatisfaction regarding sound quality, particularly hearing speech when there is considerable background noise.
Benchmarks in Bone Conduction
Bone conduction has been used in different forms, such as headband bone conduction devices and eyeglass bone conductors, for different types of hearing loss, with mixed results. But in recent years, two new approaches to treating SSD have proven popular and highly effective. Both involve bone conduction, which transmits sound directly though the bones in the skull.
When sound is “received” on the side of the non-functioning ear, it is converted to mechanical energy
that drives a vibration transducer that is embedded in a custom earpiece. Those signals are then transferred via the bones of the skull to the cochlea in the opposite ear, bypassing the outer and middle ear.
In 2002, the BAHA was approved by the FDA for SSD. This option involves surgery, in which a titanium implant is placed in the skull bone behind the ear. An abutment connects the sound processor with the implant in the bone. Sound waves received by the BAHA sound processor travel by bone conduction to the functioning cochlea on the opposite side.
A more recent addition to the available options is TransEar, approved by the FDA for SSD in 2005. TransEar utilizes the same principles of bone conduction as the BAHA, but instead of transferring sound energy to the skull at a point behind the ear, the TransEar device is positioned in the ear canal. A miniature oscillator is embedded in a custom-made shell in such a way that the oscillator makes contact with the bony portion of the ear canal. The vibrations are limited only by the very thin (0.2 mm) layer of skin in the “target area” of the ear canal. From that point, the sound energy is transferred via the bones of the skull to the cochlea in the opposite ear.
As an audiologist, I have heard many stories from patients who have been affected by SSD. They tell me of jobs they can’t do because they can’t hear on one side; of their unease in walking along a city street; of difficulty carrying on a conversation in a car; and of feeling anxiety at a party. These are the situations thatmotivated me to invent TransEar. It is really gratifying to hear stories from people who have chosen to seek a solution to SSD. I hear stories of surprise and joy at hearing children’s voices that would have been missed before, simply because the children were on their “bad” hearing side; of working confi dently in hospitals and schools without fear of misunderstanding important verbal communication; of attending meetings without arriving first to get the corner seat; and of confidently carrying on conversations in restaurants with friends.
The bottom line is that remedies for SSD are available today that dramatically improve people’s ability to understand speech in both quiet and noisy environments, to provide the sensation of sound on the deaf side and, in many cases, to improve sound localization. Since each of us has different physiology as well as lifestyle preferences, your hearing healthcare professional can help you decide which remedy best fits your needs.
Additional resources for information include:
Acoustic Neuroma Association
www.anausa.org
Cochlear Corporation
www.cochlear.com
Ear Technology Corporation
www.transear.com
Daniel R. Schumaier, Ph.D., president of Ear Technology Corporation, earned a master’s degree in audiology from the Central Institute for the Deaf at Washington University in St. Louis and a Ph.D. in audiology from Michigan State University in 1972. He is a dispensing audiologist with three offices in northeast Tennessee, and an industrial hearing conservation service with clients in 14 states. An entrepreneur at heart, Dr. Schumaier is the inventor of Dry & Store® and TransEar, holding numerous patents, both domestic and foreign.
