Types of Hearing Aids

Types of Hearing Aids

Pocket Model : Worn in a pocket or harness at chest level. It consists of the body of the hearing aid containing the microphone, amplifier and controls. A cord transmits the electrical output to a receiver, which converts this signal into sound. The receiver is attached to a mould, which holds it in place.

Behind the Ear (BTE) : The body of the instrument is worn behind the ear. It ‘hooks’ over the pinna. It is attached via plastic tubing to an earmould, which holds it in place in the ear.

In the Ear (ITE) :The complete hearing aid is in the ear or ear canal. The hearing aid is housed in a hard plastic shell which is often custom made by taking an ear impression.

In the Canal (ITC) and completely in the canal (CIC) :These aids are contained in a tiny case that fits partly or completely into the ear canal. They are the smallest aids available and offer some cosmetic and listening advantages

Spectacle Type: The hearing aid components are incorporated within a spectacle frame. It is useful for persons who require glasses along with hearing aids.

Bone Conduction (BC) hearing aid: This is used when the ear canal is blocked or in cases where conventional amplification as described above cannot be given. A BC vibrator is placed on the mastoid bone behind the ear. It converts the amplified electrical signal into vibrations. BC vibrator can be used with body level, BTE or spectacle hearing aids.

Personal FM hearing aids - A frequency-modulated (FM) system is a wireless devise that uses radio waves to deliver speech signals directly from the speaker's mouth to the listener's ears.

Hearing aids should always be used with custom-made ear moulds. Ear moulds are devices, which couple the hearing aids to the ear. Ear moulds can be of hard or soft material.

Points to consider

1. Hearing aids have different ‘Powers’ and ‘features’. The hearing aid which has the ‘right’ power and features for a particular user will provide maximum benefit. Therefore, hearing aids should always be purchased after under going a trial.
2. Hearing aids can be worn in one ear or both ears according to the hearing loss.
3. The best performance of the hearing aid can be obtained only when you use the hearing aid with ear moulds made for your ears.
4. The hearing aids may be simple ‘analog’ type or they may be digital. Digital hearing aids are much more expensive.
5. Hearing aids run on batteries. The life span and cost of different types of batteries are as follows:

Details of different types of batteries

Tips on Hearing Aid Selection

Different Types of hearing aids provide different advantages and disadvantages. The client must choose which hearing aid he/she wants based on the audiologist’s advice and their own decisions after weighing the pros and cons. Body level hearing aids are sturdy, less expensive to buy and maintain. They also have lesser problems of feedback squeal if the earmoulds are not good. The disadvantages are that

1. the microphone is chest mounted and does not give ear level hearing.
2. there is a difficulty in eliminating the effects of cloth rubbing noise and body shadow (the body may block some sounds from reaching the microphone).
3. there is a difficulty in providing advantages of binaural hearing such as localization.

BTE hearing aids are more expensive to buy and maintain. They are small and thus easy to wear in children. They offer more flexibility with respect to adjustments in the output signal. BTE provide the advantage of binaural hearing as sounds are received at normal ear level. Localisation of sounds is easy compared to even 2 pocket model hearing aids.

In the ear and in the canal hearing aids also provide advantages of binaural amplification. They are expensive and not worthwhile for children because the entire hearing aid will need to be recased if the size and shape of the ear changes. In BTEs and pocket model aids, only earmoulds need to be changed. ITEs are also not useful for profound hearing losses. In the canal hearing aids fit in the ear canal and make use of the natural resonant properties of the external ear.

It is important to remember that irrespective of which style of hearing aid is chosen (BTE or pocket level) auditory training is required because that is what largely determines the child's progress.

Care & Maintenance of Hearing Aids

• Prevent it from falling down
• Don’t spill liquids on the hearing aid
• The hearing aid should be fitted well – pocket model aid in a harness and BTE with appropriate moulds and retainers if needed.
• Cords should not be twisted or knotted.
• Protect it from dust, dirt & heat.
• Remove the battery from the hearing aid when it is not in use.
• Remember to detach the ear mould from the receiver before washing the mould. The receiver should not come in contact with water.

Trouble Shooting for Body Worn Hearing Aids

Trouble Shooting For BTE Hearing Aids

The trouble shooting chart aids to give you tips to solve only very simple practical problems. If you cannot rectify the problem using the methods suggested, do not try to do any repairs on your own. Go to a qualified electronic technician or your hearing aid dealer/service agent. Hearing aids will last longer and provide better sound quality if they are regularly serviced and any problems rectified at the earliest

Care & Maintenance of Ear Moulds

1. Keep the moulds clean and free of dirt or ear wax. Blocked moulds result in poor sound reception. Dirt may lead to infection in the ear.
2. Wash the ear mould in soapy water and clean the dirt with a wire or tooth brush. Use it only after it dries completely.
3. Do not press the mould hard over the receiver (in pocket model aids) as this can damage the receiver.
4. Replace moulds when they become loose/child can not wear the hearing aid at the normal volume level due to a squealing sound. In young children, moulds may need frequent changing (some times even once in 4-6 months) as the size and shape of ear canal changes with growth.
5. The mould should not be removed very often from the receiver as the spring loses its tension. However remember to detach and remove the receiver before washing the earmould.
6. The mould should be properly seated in place so that no sound leakage is present. If the mould is slightly loose, a little cotton, sponge or fabric may be placed in between the receiver and mould for tight sitting and sealing. This would also minimize the sound leak.
7. If the child shows any skin reaction after using the mould consult the ENT specialist.

Source: Ali Yavar Jung National Institute for the Hearing Handicapped

Related resources

1. Hearing aids / Assistive listening devices under ADIP scheme
2. Rates of hearing aids supplied under ADIP scheme
3. Body level hearing aid care