What is open technology in hearing aids?
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"Open Technology" or open fit hearing aids have changed the hearing aid industry. The word "open" in this context means the hearing aid does not completely close the patient's ear canal. Though a debate about openness among hearing professionals could be made related to the vent size of a custom made hearing aid or ear mold, the hearing aids that are most often called open technology made their appearance into the market place about fifteen years ago. Before this time, impressions were made of the ears, hearing aids build to that impression, and then inserted into the patient's ears.
The most common struggle for the new hearing aid patient was a comfort issue of how the hearing aid actually felt in the ear and sounded, particularly their own voice. Most of the time, they simply felt and sounded plugged. The clinical term for that plugged sound is called occlusion. Some describe their voice when feeling plugged as if they were talking through their nasal cavity. You can experience this by putting your fingers in your ears and talking. That's occlusion! The biggest adjustment to the plugged reaction when wearing hearing aids was sounding different to yourself and hearing on the telephone.
Open technology hearing aids solve those problems as they are not custom made and have a variety of small domes with holes on the tips of the hearing aids. The holes in the soft dome tips allow your own voice, telephone sounds, and generally the low tones in naturally to your ear. Most hearing loss is in the higher frequencies so electrical engineers in the field of sound suggest allowing the ear to process the low tones rather that making the patient completely depended on the hearing aid for every sound they hear. The result is a more natural sound experience and a much more comfortable feeling when actually wearing the hearing aid. Many patients who wear this style forget they have them on after two to three days.
Open technology hearing aids have some constraints. Thus far, they are only available in a behind the ear model. Most importantly, they will only work for a patient that has a moderate hearing loss. Feedback or the squeaking sound from a hearing aid is caused when the sound energy going into the ear from the unit's speaker leaks out and back into the microphone. Feedback commonly happens when the hearing aid is not completely down in a patient's ear canal.
So if that is how feedback happens, how can it be prevented in a style that already has holes in the dome? Won't the sound energy leak out those holes? Yes it will, and the answer to feedback control happens by software control in the digital circuit but with limitations on the power being put out by the hearing aid. In other words, open technology has to be a lowered powered hearing aid for the internal feedback control function to not be overwhelmed. If a patient has a really severe hearing loss they are not a candidate for open technology.
Common adjustment problems in traditional custom hearing aids are now much easier to conquer than in previous generations of technology so the severe loss patient has greater options to hear better comfortably, but open technology may not be one of those options.
Custom made hearing aids have both the microphone and speaker in the same small space. Behind the ear hearing aids can have a custom made impression on the end of a small tube that connects to the tip or horn of the hearing aid. Sound is broadcast through the tube. Open technology, again, fits discreetly behind the ear with the microphone on the hearing aid and the sound being broadcast through a small coated wire into a miniture speaker covered by a dome with holes that sits comfortable about a quarter of inch from the ear drum. A hearing test would determine if you are a candidate for open technology.
Hearing care is healthcare. If you have the symptoms of hearing loss let a professional help you find out why. The hearing professional will help you sort out the technology level to meet your need, your budget, and answer your hearing need questions.