Types of Hearing Aids
Behind-the-ear Hearing Aid (BTE)
BTE models are housed in small curved cases which fit neatly behind the ear. It is connected to a small piece of tubing which fits into a custom made ear mold. They can cope with losses ranging from mild to severe. The microphone, amplifier, and receiver are all housed in the hearing aid case, connected to the ear mould by a short plastic tube. Some models have a tone control as well as a volume control, and some come equipped with a telephone pickup device known as a T-switch.
Some models can also have a jack for direct audio input. The controls are easy to manipulate and is used by many hard of hearing people.
In-the-Ear Hearing Aid (ITE)
ITE aids, including the newer tiny canal aids, fit directly in the ear canal, supported by the ear shell itself. These models have no external wires or tubes and are very light in weight. They have a volume control, but may have no tone control. Generally they are used for mild to moderate losses, but some newer ITE's are powerful enough for severe losses. The tiny canal aids are useful if the hearing impairment is mild.
In-the-Canal Hearing Aid
This type of hearing aid is very small and fits into the ear canal. Because the entire aid fits into the ear canal, it can only be used by those who have an adequate sized ear canal. There are two types of In-the-Canal aids; those that are partially in the canal and those that are completely in the canal. These types of hearing aids are smaller and are harder to handle for many people. They are generally used for people with a high-pitched hearing loss and did not have T-Switches, however, the technology is improving that these and other improvements are now available.
It would not be advisable for those who experience moisture or skin problems in the ear canal to use this type of aid. It requires good manual dexterity to manipulate because it is so small. Its size however, can be an advantage, as it is virtually unnoticeable.
Completely-in-the-Canal Hearing Aid
Through the past number of years, huge developments have been made in creating smaller hearing aids for the hard of hearing. One of the products of this progress is the Completely in the Canal (CIC) aid. These small hearing aids sit in the canal of your ear and are almost invisible to the everyday person. Because of its small size the benefits are large; there is a reduction of the occlusion effect (a hollow sound and/or plugged up sensation), absence of wind noise, less power is needed reducing feedback which in turn allows a person to use the telephone normally. CIC aids are best used for those who have a mild to moderate hearing loss, including those with severe high frequency losses. More considerations to take into account would be the size of the ear canal, the aid’s cost, and the patient’s ability to handle small objects.
Also there is more than one option of CIC aids available which enables the customer to find the best aid for them. Different brands have different circuits and case designs and various brands also have remote controls so one is able to adjust programs for the situation in which they are found (for music, for loud rooms, for conversation). In addition to the remote version there is the digital model which can switch to different programs without using any remotes or controls at all.
Of course because of the CIC’s small size and exact placement, getting sized and fitted for CIC aids can be a lot more time consuming and may take several trips to the audiologist before they are right for you.
Open Fit Hearing Aids
Open fit hearing aids are similar to the behind-the-ear (BTE)
style because the electronic portion sits outside
the ear. However, these hearing aids are much smaller and the tubing that brings
the sound to the ear is very slim and almost invisible with a small flexible tip
that sits in the ear canal. The small tip in the ear results in an open fit
without 'plugging' the ears. An open fit hearing aid usually results in a more
comfortable fit, a more natural sound, and can eliminate problems with your own
voice. However, the open fit hearing aids are not appropriate for severe hearing
losses and are best for persons with mild to moderate high frequency hearing
loss.
Analog and Digital Hearing Aids
Analog Hearing Aids are the least expensive option for those who are hard of hearing and because of this they can be some of the most popular choice. They are able to be programmed to suit different environments and can also be adjusted for changing levels in hearing loss. The problem for some with Analog Hearing Aids is the fact that all sounds are amplified. This means that instead of just the sound you want to hear being louder, everything within the room is thunderous. In a noisy setting this can make it even harder for a person to hear. Choosing an Analog Hearing Aid is a personal preference which needs to be made through a lot of discussion and financial situations.
A Digital Hearing Aid is a more expensive option but for some it is the only alternative. The Digital Hearing Aid converts sound into digital signal which in turn makes it easier to differentiate between background noise and speech. Because of its digital capability, the aid is easily programmed to suit the user’s specific hearing loss. They can also adjust the programs as the person hearing loss changes.
For some the change from an Analog Hearing Aid to a Digital Hearing Aid does not have enough of a difference to outweigh the cost, but for others it is the difference between having a clear understanding of the world around them and being left in the dark. It is important that people take the time to assess the options and see what best suits them.
Bone Conduction Hearing Aids
When people have deformed or no external ears the previous types of hearing aids are not suitable. In this case, aids are worn behind the ear and held in place by a head band. Sound is transmitted to the inner ear through bone. Bone conduction hearing aids also come in the "eyeglass" style. Recently, an implantable aid has been developed and is put in place by a surgical procedure. As with all new procedures, long time effects are unknown and you should discuss this carefully with your ENT Specialist.
Monaural Hearing Aid Systems
Monaural systems are those of any type which provide amplified sound for one ear only.
Binaural Hearing Aid Systems
Binaural systems consist of two complete hearing aids - microphone, amplifier, and receiver - one for each ear. For some people, the binaural system increases the directional sense, helps to separate wanted sounds from unwanted background noise and may increase the pleasure of hearing.
The CROS or "Cross-Over" System (Contralateral Routing of Signal)
The CROS system places the microphone beside the poor ear and feeds the amplified signal to the better ear. This system may improve hearing by eliminating "head shadow"; that is, it prevents the head itself from blocking off sounds from the better ear. In some designs, the sound is carried to the ear canal by a plastic tube alone, eliminating the ear mold. This leaves the good ear partially open and permits some sound to reach it directly. Recent experiments have shown that the CROS system may help make speech more understandable to people who have a high-frequency impairment in both ears. Excellent results have also been obtained in some cases by the use of a BICROS system. It consists of two microphones - one above each ear - which send signals to a single receiver which delivers sound to the better ear through a conventional ear mold.
High-frequency emphasis aids are available for people who have a hearing impairment only in the highest octaves of the speech range. For them, speech is audible, but they are unable to distinguish words readily. High-frequency emphasis hearing aids are made with just a clear plastic tube which carries sound into the ear. Sounds of lower frequencies, where the hearing remains normal, reach the ear directly through the open-mold fitting. With the progress of technology in hearing devices, you will encounter increasingly more specialized devices with more options on hearing aids. Consult your local audiologists and technical experts for information. Cochlear implants are becoming more common for the late deafened and you may encounter someone who has such an implant.