Types of Hearing Aids
Digital hearing aids come in a wide range of types, styles, shapes, sizes and colours.
Regardless of their design, all hearing aids require the same basic assembly of components - microphone/s, chips, speakers (receivers) and a battery to supply power. How these components are placed within the hearing aids is determined by the model.
Hearing aid design continues to evolve with manufacturers providing an extensive range to suit every taste and requirement. This guide gives you an overview of the types of hearing aids available:
Behind-the-ear hearing aids
Behind-the-ear hearing aids are often abbreviated to BTE or occasionally OTE (on-the-ear). They are one of the most popular types of hearing aids. As the name suggests, behind-the-ear devices are designed with the electronic components in a casing which sits behind the ear, with a tubing of some kind allowing the amplified sound to travel into the ear canal itself.
On the casing, there may be controls that can be accessed by the wearer – usually a volume and/or programme button. Remotes can also control some BTEs.
Wireless connectivity is currently very popular, with hearing aids able to link via a transmitter or even directly to TVs, smartphones, and external microphones, offering even greater help to the wearer for specific listening situations.
Advances in electronics and component design have allowed many manufacturers to produce extremely small and light BTE products; in some cases the part that goes behind someone’s ear is not more than an inch in length.
How are BTE devices fitted?
A traditional BTE fitting uses an earmold. An impression of the outer ear and ear canal is taken using quick-drying silicone material. This impression is sent to a lab, and a customised earmold is created.
Earmolds, which can be made of hard or soft materials, and are usually clear or pinkish in colour, but brightly coloured or decorative earmolds are also manufactured on request. A hole (bore) is drilled through the earmold and an earmold tubing inserted. The tubing then attaches to an ear hook on the BTE.
In the past decade, the so-called thin-tubing fitting has increased in popularity. Thin-tubing fitting usually refers to ‘open-fit’ BTEs. Substantial improvements in hearing aid technology and design have enabled hearing aid users to move away from earmold fittings and consider open-fittings instead, of the customised ear mould.
Thin tubings are very thin (2mm diameter or so) tubings that direct the sound from the casing into the ear canal. Instead of the tubing going through the bore of the earmold, they are pre-shaped to bend into the ear canal and a soft ‘dome’ is attached to the end of the thin tubing to improve wearing comfort.
Domes vary in size and most manufacturers have a range of sizes and styles.
One of the advantages of open-fitting products is improved wearing comfort compared to earmold fittings. The thin tubing and dome allow for more natural airflow in and out of the ear canal, something which was is difficult to achieve with earmolds.
Having the ear canal less blocked up helps to keep the sound of one’s own voice more natural and chewing and drinking sounds are not over-amplified.
A disadvantage of open fitting BTEs is that very severe hearing loss usually cannot be accommodated, as the risk of feedback or whistling from the hearing aids increases substantially as the degree of hearing loss increases
BTEs come in a wide range of sizes.
Different sized hearing aid batteries are used in some designs, as
well as bigger or smaller amplifier units for more or less amplification. Smaller batteries (e.g. size 10) will need to be replaced much more frequently than bigger batteries (e.g. size 13).
‘Power’ and ‘Super-power’ BTEs will have bigger amplifiers, and usually also operate on bigger batteries. Even these powerful products are now produced in considerably smaller designs than a decade ago.
Receiver in canal (RIC) hearing aidsRIC or RIE (receiver in ear) hearing aids have been classified as a sub-type of the behind-the-ear category of products. However, as more and more RIC devices appear every year from manufacturers, RIC hearing aids are now considered a category on its own.
RICs look very similar to BTEs - they have a casing containing components and user controls which sits behind the ear and then a tubing coming down over the top of the ear, ending in the ear canal.
The major difference, however, is that this tubing actually contains a wire, which has a receiver (speaker) on the end. So the speaker of the hearing aid now sits within the ear canal and not in the casing behind the ear.
The end of the receiver tubing or wire has a soft dome on the end, which makes the fitting more comfortable within the delicate skin of the ear canal. Custom earmolds are however also made for RIC hearing aids.
As with thin-tubings, the domes come in a variety of sizes and are often used as a way to further ensure feedback is kept to a minimum when the RIC is being used. The domes also serve as additional protection against wax and moisture ingress.
What are the pros and cons of RIC hearing aid types?
Having an electronic component in the ear canal does increase the risk of it being affected by wax build-up or skin debris or moisture. In most RIC designs, the receivers also have a wax guard built into them, which can be changed as part of the general care and maintenance required for the hearing aid.
Some RIC wearers only change their wax guards every few months; others may need to change them much more frequently.
Because one of the major electronic components is not in the casing behind the ear, space is saved, allowing RICs to be made in surprisingly small designs. The fact that the receiver component lies in the ear canal means that the distance between it and the hearing aid microphone is increased, certainly compared to the distance between these components in a traditional BTE. The risk of
feedback is thus decreased by this physical design element.
+ Small Design
+ Choice of amplification
+ Less risk of feedback than with the equivalent thin-tubing BTE
- Risk of wax build-up & more careful maintenance required
- Cost of replacement receiver
In the canal hearing aids
Despite the increase in the availability of small RIC and thin-tubing BTE products, many people still prefer the idea of in-the-canal hearing aids. For most people without hearing aid experience, ITC (in-the-canal) or ITE (in-the-ear) hearing aids are still thought to offer a more cosmetic fit and many people ask for these initially when investigating hearing aids for the first time.
Most manufacturers distinguish between the ITC and ITEs, usually on the basis of size. ITC models are generally manufactured smaller than ITEs (the ‘ear’ part of the description referring to the product filling some of the actual concha or bowl part of the outer ear, rather than just the canal and entrance to the canal sections). ITEs may also be further categorized as ‘full-shell’ or ‘half-shell,’ which describes how much of the concha section is filled.
How are ITC hearing aids fitted?In ITC hearing aid all the components sit within a casing, usually known as a shell. This shell can custom-made for an individual ear, after an ear impression, is taken. Some products are also available in a ‘one-size-fits-all’ shell, which is modelled for the average adult ear canal.
What are the pros and cons of ITC devices?
If a comfortable fit is achieved, many people find ITC products easy to wear, and easy to put in and take out. However, even if the fit is physically comfortable within the canal, many people, particularly those with more mild/moderate high-frequency losses do report feeling rather ‘blocked up’ with something now in their ear. This is referred to as ‘occlusion. ’ Some people will acclimatize to this sensation very quickly; others may struggle to get used to it.
Occlusion can be minimized by drilling a hole through the shell, known as a ‘vent.’ This can, however, rise to an increase in feedback so we recommend you take advice before drilling a hole!
+ Easy to put in/take out
+ Cosmetic Design
+ Good with spectacles
- High maintenance
- Blocked up sensation
Care and maintenance of ITCs is more involved than with BTEs, and similar to what is required for a RIC device. The most important thing is to keep the instrument free from wax build-up and as dry as possible – something which can be difficult, as all the components are now worn inside the canal.
All ITCs will be manufactured with some form of wax guard in place, which will need to be inspected daily (or whenever the ITC is put in the ear) for any wax build-up. Most wax guards can be replaced by the wearer, some people replace as frequently as once a week, others once every few months.
An advantage of ITC fittings over those of RIC and BTEs comes to the fore when people complain about having to wear spectacles as well as hearing aids.
While most people do get used to wearing a BTE/RIE with their glasses, it can be troublesome for some and an ITC device does not interfere with the arms of ones glasses at all.
Completely in the canal hearing aidsCompletely in the canal hearing aid types or CICs, refer to those in-the-canal products which are specifically manufactured to sit deep within the ear canal. A well-manufactured CIC may really be invisible, even when the ear containing the CIC is viewed directly from the side.
Not surprisingly, the components used for CIC products are the smallest available – which does mean that battery life and available amplification is limited. User controls are also limited, at most a programme button only (although some can still be controlled via remote control).
For most CICs, the quality of the ear impression taken for the shell is critical and some manufacturers insist on providing further training to those hearing health professionals who wish to fit their CIC products.
The same advantages and disadvantages apply to CICs as for ITCs.
Body-worn hearing aids
Body-worn hearing aids are devices where the electronic components are situated in a little box- shaped container, which is not worn on or in the ear, but on the body.
The box is usually clipped to a pocket or belt or worn around the neck and the amplified sound is delivered to the ear via a cord and earphone or custom-made earmold.
The microphone is situated on the box, so wearers must be aware that if they wish to have any sound amplified, the microphone on the box must be able to pick up that sound.
What are the pros and cons of body-worn hearing aids?
Body-worn hearing aids were very popular a few decades back, as they were, at the time, the only way to provide a lot of power for more severe hearing losses.
As technology in smaller BTEs improved, the need for body worn products decreased sharply. However, some body-worn hearing aids are still produced by some hearing aid manufacturers. New markets have opened up within developing countries – where body worn hearing aids are used for less severe hearing losses because the batteries powering the devices are AA or AAA types; which are much more accessible and cheaper than hearing aid battery options.
Some body-worn products have also been produced to run on solar power.
+ Battery life/cost
+ Powerful amplification
+ User controls
Spectacle worn hearing aidsSpectacle hearing aids, or hearing aid glasses refer to designs where a hearing aid is built into or attached to the arms or frame of a pair of spectacles. As many people have a vision as well as hearing impairments, it surely makes sense to combine the two? However, successful fittings using spectacle hearing aids are difficult to achieve and it is quite telling that many of the world’s major hearing aid manufacturers no longer, or have never, produced a product within this category.
What are the pros and cons of spectacle hearing aids?
Spectacle devices are often recommended for those individuals with ‘conductive hearing loss.’ This is where the inner ear is functioning well, but the outer and/or middle ear parts are affected, such that the transmission of sound through to the inner ear is obstructed to a large extent.
The hearing instrument part of the glasses is designed to sit right on or very close to the mastoid bone of the skull, within protects the inner ear. The amplified sound coming out of the transmitter will then stimulate the inner ear via vibrations of the bone.
+ Recommended for conductive hearing loss
+ Can offer a disguised hearing solution
- Difficult to fit
- Removing glasses removes the hearing ability
More common sensorineural hearing losses can be accommodated by spectacle hearing aids which deliver the amplified sound to the ear via a tube or earmold.
These types of fittings are not popular; as one’s choice of glasses frames and hearing aid is severely restricted and when the glasses are removed, the hearing aid needs to be taken out as well.