Tinnitus and hyperacusis

Tinnitus

What is tinnitus?

Tinnitus is an awareness of sound which, unlike normal environmental sounds, does not originate outside the body. This can take on many different forms, with descriptions of ringing, whooshing, white noise and other combinations. It can be very brief, of moderate duration or noticed over a longer period. It can affect one ear or both ears, or it can fluctuate between the sides.

Sometimes, tinnitus can occur where there is awareness of sounds within the body, including the pulse of blood rushing past the ear(s), known as pulsatile tinnitus. Alternatively, other structures in the area may also give rise to some noise, for example equalisation of the middle ears and clicking of the jaw joints. Additionally, and more rarely, patients may be aware of movements and contractions of tiny muscles within the middle ears or frequent opening of the Eustachian tubes, which help to equalise the middle ears.

Alternatively, people may be aware of different sorts of sounds, the typical ringing, tones or white noise type sounds which people associate with tinnitus.

Why do we have tinnitus?

The auditory system which allows us to hear includes the inner ear hearing organs, complex nerves and other structures which connect the hearing organs to the hearing centres of the brain. The inner ears develop very early, at around 12 weeks of gestation, and they are very soon electrically active, and remain so throughout life. The inner ears convert sound energy, which arrives as vibrations through the the air, via the eardrums, into tiny electrical currents, like morse code. These currents pass up through the very complex nerves towards the hearing centres of the brain and are then decoded- for example, Into the sound of a voice, a bird singing, a car engine, etc. We interpret those particular Morse code signals into ‘sounds’ which we recognise, based on our experiences. In addition to these specific electrical currents, as a result of sound reaching the inner ears, there are also electrical currents passing along the system all the time- an ‘electrical noise’. This is normally damped down by the control centres of the auditory system, like a sound engineer does in a recording studio or concert, so that we can concentrate on the sounds which we are listening for, rather than the electrical noise.

Sometimes, for various reasons, we become aware of the electrical noise more than we should, which is then perceived as ringing, a tone or white noise – tinnitus.

Specific causes of tinnitus

In most cases, there is no obvious cause for this. It just seems to happen. Sometimes there has been an event which sets it off, for example a loud noise near the ear, a blow to the ear, an ear operation or a head injury, for instance. In other cases, where hearing has reduced for whatever reason (for example in the elderly), tinnitus can be more common, as the normal background sound (which would normally drown out the awareness of the electrical noise) is no longer heard, so the tinnitus is noticed more prominently. For this reason, hearing aids can be really helpful if the hearing has been reduced, not only to improve the hearing but also to drown out the electrical noise by having better access to quieter environmental sounds.

The same issues are seen at quiet times, for example settling down in bed at night. There is less environmental sound to drown out the electrical noise, and so some patients may benefit from some lower volume noise in the background, which is discussed below.

Although many people are concerned that their tinnitus might be caused by a worrisome underlying cause such as a brain tumour, this is in fact rare. The hearing and balance nerves run very closely together from the hearing and balance organs towards the base of the brain. Rarely, a benign tumour can develop in the lining of one of the balance nerves- this is known as a vestibular schwanomma or acoustic neuroma. This can slowly squash the hearing nerve, particularly when it is in a narrow bony channel at the base of the skull, leading to reduced hearing and/or tinnitus on one side. For this reason, patients with one-sided tinnitus and/ or hearing loss are generally referred for an MRI scan to rule out this sort of pathology, although it is rare. In the majority of cases, even with one-sided symptoms, there is no such underlying cause.

Why is tinnitus unpleasant?

The auditory system developed in higher animals primarily as a way to avoid predators, so that animals who could hear predators coming could then escape- it is a big survival advantage. Although we now use our ears when we are talking to each other and for lots of other enjoyable reasons, such as listening to music, it is worth remembering that hearing came about to allow us to survive. The auditory system is very closely linked to the primitive centres of the brain which give us a sense of fear, unpleasantness and noxiousness, leading us to flee. Unpleasant sounds, such as a very loud noise or the sound of a snake hissing or a wolf howling nearby will make us fearful and apprehensive- as a protective mechanism. In the same way, when we become aware of electrical noise which we perceive as tinnitus, this also makes us feel uncomfortable. The more we are aware of it, the more we think about it and the more unpleasant it makes us feel: a vicious cycle, which is worsened by our thought processes.

Furthermore, at times of particular tiredness or stress, for example after a hard week or at the end of the day, when we are more on edge, the tinnitus can be worse as a result – the noxiousness becomes more problematic. In the same way, some people who have a particularly worried or anxious personality may find that the tinnitus is more intrusive and unpleasant, perhaps with more associated distress.

How is tinnitus investigated?

In most cases, there is no obvious cause for the symptoms. However, it is generally reasonable to consider hearing tests, to look for any obvious reduction on either side, and to make sure that there is not one sided hearing loss.

In some situations, particularly where there are one sided symptoms, an MRI scan of the brain and inner ears may be needed.

How is tinnitus treated?

Very importantly, tinnitus is very common in the population at one time or another, and in most cases it will become less noticeable with time, without the need for any formal treatment.

A generally positive outlook is really important. Considering the negative thought processes described above, which make the tinnitus more noticeable, being aware that underlying pathology is rare and being optimistic will generally make the symptoms less intrusive over time.

It is also important to manage any hearing loss, because access to environmental sound will make other electrical noise less noticeable. Hearing aids may be considered, depending on the severity of any hearing loss.

In the same way, at quiet times, for example when settling down to sleep, and where there is less environmental sound, the tinnitus can be more pronounced. At these times, it can be useful to have some white noise in the background. A variety of options are available, including apps for mobile phones or tablets, a fan or air purifier and white noise generators, for example under a pillow. This sort of bland noise is generally more practical than, for example, a radio where it can be distracting to be listening to speech or music when trying to fall asleep at night.

Given the complex thought processes which make tinnitus more prominent, specific therapies can also be used for more problematic cases. Cognitive behavioural therapy (CBT) has been used for a variety of reasons, and it can be used specifically for the thought processes associated with tinnitus. There is in fact some good evidence to support this. Some patients may be referred to a specialist in this area.

Tinnitus summary points

Tinnitus is very common in the population- many of us are affected at one time or another

It usually improves with time, and without specific treatment

It is very rarely associated with any significant underlying pathology- an MRI may be requested in cases of one-sided symptoms

There are several areas of management, including a generally positive outlook, white noise in the background and managing any hearing loss with hearing aids. CBT can also be used in some cases.

Hyperacusis

What is hyperacusis?

Hyperacusis is a sensation of discomfort or pain when exposed to everyday loud noises. All of us will find very loud noises uncomfortable, for example being close to a jet engine or a shotgun without ear defenders. however, in some cases, in both children and adults, the same sort of discomfort and distress is encountered with more common every day noises. These include hairdryers, hand dryers, noisy classrooms, roadworks and police sirens, for example. All of these sorts of noises are regulated to be safe and not damage our ears, but nonetheless, some people find them very unpleasant.

What causes hyperacusis?

In the discussion about tinnitus, above, the auditory system is described in detail. This developed in higher animals to help avoid predators, and it is very closely linked to the primitive parts of our brains which give us a sense of fear and unpleasantness, and help us to escape from dangerous situations. Sounds which we know are unpleasant and which are linked with danger then make us more fearful and uncomfortable.

In some people, this same sense of discomfort and distress may be produced by the sorts of everyday loud noises which most people do not find as upsetting. This can be quite specific to certain noises, and not just because of how loud they are. For example, some children will find hairdryers and hand dryers really upsetting, but will have no difficulty in spending time in a very noisy playground with shouting and screaming all around.

As with tinnitus, hyperacusis may be more commonly seen in certain groups, for example people who have some underlying stresses or anxieties, as particular thought processes and apprehensions may make certain loud sounds more distressing for some people than they are for others. Interestingly, we also see hyperacusis in some patients who have a degree of hearing loss, for example children with glue ear and elderly patients who have age related hearing loss at high frequencies – once the sound is above a certain level and there is some distortion, they may find the experience unpleasant.

How is hyperacusis treated?

It is really important to be aware that exposure to most every day loud sounds is unlikely to cause any damage to the ears. There are of course exceptions, such as unmuffled car or motorcycle exhausts, firearms, power tools and construction/ DIY situations. However, most of the circumstances in which patients have hyperacusis occur at a sound level which is not dangerous to their ears or to anyone else.

Apprehension and anxiety around noisy situations will make the whole experience worse. Some people will try to avoid noisy circumstances, or use earplugs or ear defenders where the sound intensity is not great enough to cause damage to the ears (i.e. in most every day situations). This sort of avoidance behaviour generally makes the apprehension around loud sounds worse. Instead, it is generally better to build up exposure to the loud sounds in non-threatening circumstances (for example in the case of young children, taking them to a playground or park), rather than shielding them from these noises, which can make things worse. In some cases, attention to underlying stresses and anxieties is important, and in extreme cases, specialist therapy may also be useful, but this is generally not required.

Further information

There is some excellent information all about tinnitus and hyperacusis in the British Tinnitus Association website.