All about hearing aids

Yesterday’s technology…

During the nineteenth century, ear trumpets, originally used by sailors to amplify sound over a long distance, were widely used by the hard of hearing…these were gradually overtaken by ear cornets, which were smaller and (slightly) less obtrusive

Simple Ear Trumpet

This model was probably used in the 1700s. Humans have most likely used versions of the ear trumpet ranging from bull’s horns to seashells for thousands of years.

Better yet, some of these hearing aids could even be used for self-defence!

Ear trumpets

Ear trumpets were used in the 1800’s and were made of various materials including silver and tortoise shell. Some of the trumpets were collapsible for portability; size and shape related to the degrees of loudness as well as to the frequency levels transmitted. Some of the ear trumpets were concealed in objects such as canes.

Electric hearing aids

The transition to battery-powered hearing aids occurred in the early 1900s. Initially the battery packs were large and were carried in separate boxes or strapped to one’s leg. The early aids were carbon type, followed by vacuum tube aids introduced in 1939.

In 1944, the first vacuum tube hearing aid was developed which contained the battery inside the aid. The first transistor hearing aid was introduced in 1953.

With the development of the transistor, the aids were able to become smaller and more powerful. The use of microchips for programming hearing aids was introduced in 1985 to better meet individual needs.

Digital technology

Why does music from a CD sound more crisp, clear, and distortion-free than music from a record or tape? The answer, at least in part, is the difference between analogue and digital sound processing.

Digital hearing aids have one or more microchip processors inside them that convert analogue sound waves into the zeros and ones of computer language.

Sound in this format can be processed more quickly and more efficiently than analogue sound waves; in fact, incoming sounds are sampled at a rate of a million or more times per second.

The digital aids circuitry analyses these sound levels and frequencies, manipulating them to provide a more efficient match to an individual’s hearing profile.

Digital hearing instruments compensate for different listening situations in a far more flexible, accurate and complex way than any analogue circuit!

Different styles

Completely-in-the-Canal (CIC) hearing instruments (a)

This is the smallest type of hearing aid available and it is almost invisible in the ear. All the components are housed in a small case that fits far into the ear canal. This takes advantage of the ears own anatomical design and ability to collect sound naturally.

CICs are custom-made for each ear; however, these hearing aids are restricted to people with ear canals large enough to accommodate the insertion depth of the instrument into the ear. Also, the CIC style uses a very small battery that requires good manual dexterity. This type of hearing aid is not suitable for people with the more profound hearing losses or require loop systems.

In-the-canal hearing instruments (ITCs) (b)

A little bigger than the CIC, the ITC hearing aids also fit far into the ear canal. Canal hearing aids use a slightly larger battery than the CIC style. This style is used for mild to moderate hearing losses.

In-the-ear hearing instruments (ITEs) (c)

These hearing aids can be used for a wider range of hearing losses. Due to their larger size, ITEs can accommodate larger sound amplifiers and more features such as a telephone switch. They are also easier to handle for many people.

Behind-the-ear hearing instruments (BTEs) (d)

In BTE hearing aids, the electronics are housed in a case that fits behind the ear. Tubing and a custom-made earmould direct the sound to the ear canal. Due to its robust design, this style is specially recommended for children. BTE hearing aids can provide more amplification than smaller devices due to the stronger amplifier and larger battery. This style is available in several colours to match people’s hair and skin tone or in bright, fun colours for children.

Children’s moulds can now be made in the style of their favourite football team!

This ‘behind the ear’ style (e) shows an instrument with a ‘slim tube’ i.e. there is no mould. Not suitable for profound hearing losses.

A RITE style (Receiver In The Ear) (f)

This relatively new style of hearing aid is becoming increasingly popular due to a number of factors. Many people have been put off because of the looks of traditional hearing aids, but this style not only addresses this issue, but it also has a number of features which in turn presents significant benefits to the hard of hearing, namely:

• There is no mould so you get a very high level of comfort.
• Digitally programmable directly from your audiogram so the hearing aid produces sounds that YOU want to hear - not what a manufacturer thinks you should hear!
• Can be reprogrammed on the laptop if your hearing changes which means that you don't have to replace the aid therefore making significant savings.
• This can (but not always) be done at your home, which is so easy and convenient. This is why it is vital to qualify this as many nationals prefer see their clients in a branch.
• If required, a remote control can be supplied where the user requires more direct input. This is also a significant help to the hearing aid audiologist, as the software contains datalogging to show preferences under various listening situations.
• Tailor-made to take account of the way YOU would like to hear – this can also take into account sounds that you find invasive which can be a major problem with traditional systems.
• Very simple and easy to use - can be obtained without any controls which means:

A hearing solution that is uncomplicated

Ask your hearing professional to choose the absolute best instrument based on his/her experience – as you may expect some hearing aids work far better than others!

A number of algorithms (programs) should be individually tailored to your needs. Situations vary enormously – in the morning it may be quiet with just the radio on but later on you may experience differing noise levels as you make your way to the shops i.e. traffic, screaming kids etc.

Even when you sit down for that cup of coffee, the environmental noises will be different – consider all the dynamic noises around you from air conditioning, people chattering, knives and forks, cutlery etc etc, the list goes on. When you consider that the voice is another noise after all, you begin to realise what your hearing aid has to put up with, especially when you want to hear what your friend is saying above all the other noises with which it is competing.

Your hearing aid has to cope not only with all these situations but all the different accents and inflections that each individual voice produces.

These instruments can also have a very impressive fitting range; if there is any further deterioration a ‘dedicated’ mould can be taken which simply fits on to the end of the speaker that then fits snugly in the ear canal.

This style is a personal favourite of mine, with many favourable reports for not only the first time user, but also it is increasingly noticeable with people who have worn hearing aids before. In fact, I have noticed a significant rise in the number of people approaching me at a younger age.

 

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