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Ultimate Hearing Aid Guide.
Hearing Aid Types
Hearing Aid Types
Hearing aids have delivered huge benefits to individuals afflicted by hearing loss in the past 50 years, and they continue to develop at a rapid rate. For those who are new to the world of hearing aids, it sometimes comes as a surprise to find out how varied their internal and external features can be.
Because choosing the correct hearing aid makes a huge difference to how well it performs, it's essential to learn more about what these devices do (and what they don't). This guide will introduce major varieties such as BTE, RIC, ITE, CROS, and BiCROS devices, and help you find the ideal hearing aid for your specific needs.
If we break it down, hearing aids are quite simple devices. All they need to do is take noises from the outside world, receive them, amplify them, and then send them to a speaker which conveys them into the ear of the wearer. At this simple level, hearing aids are just a very specific, technologically advanced form of speaker - but there's much more to the technology behind them than that, as we'll see.
For one thing, there is the microphone. This tiny component has to be sensitive enough to pick up music, conversation, and ambient sounds and have the resolution to do so as close to the human ear as it's possible to be. But modern hearing aid microphones need to do more than this. They are also often "directional", which means they can pick up the source of noises, and focus their collection efforts in that direction, improving the quality of the resulting signal. Directional systems usually involve two or more microphones which are both placed inside the hearing aid. By triangulating the distance between them and the strength of external noises, the hearing aid can calculate where sounds are coming from and point the "null" part of the microphone directly towards it. This reduces white noise and interference, blanking out other people's chatter and ambient sounds.
After sounds have been received by the microphone, the hearing aid then turns them into a signal to be amplified, and there are two broad ways of doing so. Firstly, there are analogous hearing aids which convert vibrations from sound into electrical impulses, which in turn pass through an amplifier to make them suitable for transmission. The second type are digital hearing aids, which convert sound into binary data. Both types are still widely available, but digital designs are becoming dominant due to their superior adaptability and ability to work with directional microphone systems.
The third key element of a hearing aid unit is the speaker, which as we'll see can be placed in a variety of different positions. In all cases, they work by delivering amplified sounds to the cochlea, which covered in cilia - a kind of hair which turns sound into nervous impulses, which in turn are interpreted by the brain. In many cases, deafness results from the decay of these cilia, and hearing aids can help compensate for that process.
Aside from those core components of hearing aids, it's also worth noting that advanced versions have many more components. Some have active noise cancellation to reduce unwanted ambient noise. Others feature Bluetooth receivers which can stream audio from mobile phones, mp3 players, computers, or TVs. Many also include "telecoils", which can pick up specific audio feeds such as museum tours or academic lectures. The majority have processing units which store preset programs, and manage all of the various features.
Finally, and very importantly, all have batteries to supply power to their various components. These batteries come in various sizes, and deliver varying amounts of power. That's why you'll find that most hearing aids have various price points, which correspond to weak, medium, and strong models. In advanced hearing aids, batteries can be recharged, but many still require manual changes.
So plenty of innovation and technology goes inside the average hearing aid. The same level of engineering applies to the external aspect of hearing aids as well. For instance, their cases come in a range of different shapes which are adapted to the shape of the human ear. Designers need to balance comfort, ergonomics, the need to fit in internal components, and cosmetic factors – not an easy challenge.
If the hearing aid involves the use of an “earmold” (which contains the speaker), then this has to be precisely molded to suit the shape of the wearer's ear. This is essential for a couple of reasons. Firstly, an ill-fitting earmold is uncomfortable, but it's also dysfunctional. If the seal between the earmold and the ear's concha bowl is imperfect, the hearing aid's acoustic properties will be compromised. But there are some exceptions. In cases where hearing loss is not too severe, earmolds do not need to be airtight, and can be sculpted to look as unobtrusive as possible.
Now we've looked at the interior and exterior aspects of hearing aid design, let's move on to discuss the different hearing aid varieties the market has to offer.
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