Most of us take our hearing for granted, but the ability of the human ear to collect and interpret sound is the result of an amazing and delicate mechanism. Sound is made up of vibrations that travel as waves through the air, much like the waves on the surface of water. Our ears pick up the waves and convert them into electrical signals which our brain interprets as sound.
The ear is divided into three parts:
The outer portion of your ear that you see is called the pinna. You have one pinna on each side of the head to help you localise where sound is coming from. They are shaped to collect and direct sound into the ear canal. Once the waves enter your ear canal, they meet your eardrum, a thin membrane that vibrates in tune with the waves that hit it.
The energy from these vibrations is transmitted to three tiny bones of the middle ear called the malleus, incus and stapes; these are the smallest bones in your body and are also known as the hammer, anvil, and the stirrup because of their shape. These three tiny bones turn vibrational energy into mechanical energy, and the energy is carried to a snail-shaped organ, called the cochlea.
The cochlea is filled with fluid and houses thousands of tiny hair cells that transmit sound information to the brain. As energy is passed to the cochlea from the malleus, incus and stapes, the fluid in the cochlea moves in a specific pattern, and the hair cells are stimulated. The hair cells convert this energy into nerve impulses that are then carried to the brain by the auditory nerve. Your brain can then interpret the sound collected from both ears, even when it is mixed with background noises or interference.
Unfortunately, there are a number of outside influences that can damage the tiny hair cells that turn energy into nerve impulses, making it harder for your brain to hear and interpret sounds. Exposure to loud noise, such as working in a factory, loud music or other noisy environment is one way these hair cells can be damaged. They can also be affected, either temporarily or permanently by sudden extreme noises, trauma and by some drugs. But of course the commonest form of hearing loss is caused by advancing years. As we age so our hearing abilities reduce.
Whilst it is difficult to prevent the damage caused by the ravages of time, you can prevent your hearing from being damaged by wearing ear protection when you are exposed to by extreme noise. Simple earplugs or ear defenders are readily available and if used correctly will offer protection. If you are in a noisy environment but have a need to still hear what it is going on around you, electronic ear defenders are available, or you can have special custom ear protection made for you by an audiologist.
Please also remember that if you listen to a lot of music, particularly using personal listening devices such as earbuds or headphones, you can cause damage to your hearing over time if you listen with the volume turned up too high. You may not even be aware of this if you habitually listen in noisy environments such as trains – when commuting for example.
Noise-cancelling headphones can be useful in these circumstances.
It’s estimated that around one-in-seven will have some kind of hearing loss during their lifetime. So what is hearing loss and how can it be corrected? The sensitivity of our hearing is indicated by the quietest sound that we can detect, called the hearing threshold. Your threshold can be accurately measured by a hearing aid audiologist, who will note on a graph the quietest sounds, at different frequencies, that you can hear. Normal hearing thresholds are not the same for all frequencies. If different frequencies of sound are played at the same volume (amplitude), some will be perceived as loud, and others quiet or even completely inaudible. Generally, if the volume or amplitude is increased, a sound is more likely to be heard.
Although accident, disease or exposure to toxic substances or excessive noise can all cause hearing loss, by far the most common factor is the passage of time. As with our eyesight, our hearing becomes less effective as we grow older and the older we are the greater the likelihood of us not being able to hear properly. This so called “age induced” hearing loss cannot be reversed and untreated can lead to other problems including ill health.
Research has shown that people with untreated hearing loss begin to opt out of conversations because they cannot hear what is being said. Relationships and work can become difficult and eventually the person with hearing loss can become socially isolated and depressed. Fortunately, whilst the lost hearing can never be restored, modern hearing instruments can dramatically improve quality of life, not just for the wearer but for their families too. The only sure way to find out if your hearing is not up to scratch is to have a hearing test and if there is any doubt at all, see a hearing aid audiologist who is a BSHAA member.
Today’s hearing aids are amazing. To think that you can fit multiple microphones, a loudspeaker and the most sophisticated digital signal processors in such a tiny, discreet device is beyond the wildest dreams of the early pioneers in this science.
Early versions of hearing aids were large because the components were borrowed from other devices like analogue radios. The first revolution came when these could be packaged into an ear level device. The next significant step was the use of digital amplifiers as this lent itself beautifully to the miniaturization of key components. Today, even severe hearing losses can be helped by tiny hearing aids made to fit the specific contours of the inside of someone’s ear canal.
Hearing aids come in so many different shapes and sizes. Importantly we are often asked ‘which is the right hearing aid for me?’ and the answer to this question is simple – the right hearing aid for you is the one that is appropriate for your hearing loss and that you are happy to use.
Your hearing aid audiologist is the person to ask which is hearing aids are appropriate for your hearing loss and your needs. Thereafter, you can decide whether you want a hearing system that it is easy to handle use and maintain or something that is invisible, but may require a bit more investment in time to use effectively.
The most commonly recognised types of hearing aid available in the UK today are – receiver in the canal (‘RIC’, a very small behind the ear device with a wire feeding sound into the ear canal).
More often used in NHS settings (depending on area) – a thin tube and dome.
This is the less-common behind the ear (with a thick tube and custom-built mould).
There are two main factors that contribute to hearing loss and these are exposure to noise and ageing. You can’t do much about the second one unfortunately but you can certainly take steps to make sure that your hearing is not damaged by excessive sound levels.
Human hearing is at its best in your early years and unfortunately will only decline with age. There is an element of luck combined with hereditary factors as to how quickly it may deteriorate, but it is safe to say that no one will hear as well as they once did in the latter years of their life.
Many people will have already been exposed to excessive noise levels at work or in their social lives. The good news is that even where this has happened, you can avoid noise levels that may damage your hearing further. The bad news is that noise damage to your hearing is permanent and will only get worse over time. Very few people lose large amounts of their hearing in one go and symptoms often show themselves as a lack in clarity when listening to others or the TV.
The first question to answer is how much noise is too much? Unless you carry a sound level meter around with you, a rule of thumb is that if you have to raise your voice in conversation with someone else at a distance of one meter, then you are probably in an excessively noisy situation. Your choices thereafter of course are:
If the first three are difficult, then you really should consider the last one. Many BSHAA members can advise upon and fit you with hearing protection. You may even ask them to provide you with an up-to-date hearing assessment to see whether your hearing is affected now and provide a bench mark for the future.
Although there is less heavy industry than there used to be, the modern world has come up with many other ways to damage your hearing through excessive noise levels;
If you are concerned about your hearing or would like advice on how to protect it, why not consult a BSHAA member? You can find your nearest Audiologist here.