The ‘sixth sense’ we don’t hear about

World Hearing Day this week was about acknowledging the importance of our sense of hearing, I would like to draw attention to a less recognised, but important, part of our ear: the vestibular system.

Sometimes referred to as our sixth sense, the vestibular system plays a critical role in balance and helps us understand where we are, and how we are moving. It is one of those things we take for granted until something goes wrong with it.

The vestibular system is composed of a labyrinth of canals and chambers. Each ear houses five individual vestibular organs which work like biological gyroscopes, constantly supplying the brain with information about the position, direction and speed of our head movement.

You can experience a number of problems with your vestibular system, especially with balance. Activities that once felt easy, such as walking, participating in sports, and climbing stairs, may take more concentration and effort, and you have an increased risk of trips and falls.

A person may also have sudden bouts of dizziness or disorientation as it is more difficult for them to sense their position, and how they are moving. People with vestibular disorders can find it hard to describe exactly what they are feeling, which highlights the complexity of the system as it operates quietly in the background, alongside our other senses.

The vestibular system can be affected by a virus, or a knock to the head. It can be disturbed by what we call ‘loose crystals’ that have come off the gravity-sensing organs and move around inside the canals. When disturbed, the vestibular organs may send incorrect signals to your brain about your position and movement, so it seems like the world is moving or spinning.

You may have also experienced spinning when you’ve had too much to drink. That’s partly because alcohol affects the brain, but also because it gets into the fluid and tissues of the vestibular organs of the ear.

There are several ways in which the vestibular senses and hearing are related. The first is the physical connection. The sensory organs of hearing (cochlear) and balance (vestibular) make up the inner ear and are connected by a small duct.

The inner ear is filled with a unique fluid which drives the function of both sets of organs. Fibres that carry information from these organs to the brain lie next to each other, forming the eighth cranial nerve. This close connectivity means that if something goes wrong in one sense, there is the potential for it to affect the other.

An example is a condition called Ménière’s disease, which is associated with fluid build-up in the inner ear, usually beginning with the organ of hearing, the cochlea. In addition to hearing loss and ringing in the ears (tinnitus), people with the condition usually experience attacks of a spinning-type of dizziness due to the effects on the vestibular organs.

Not all causes of hearing loss are associated with loss of vestibular function. However, vestibular problems are more common in people with hearing loss, particularly those with severe hearing loss.

A second, and perhaps less obvious, way that hearing and vestibular function are related is through their role in helping us understand our position and movement in relation to the world around us.

While the vestibular system provides information about head movement, our sense of hearing also provides cues that help us to orient ourselves. For example, if a sound, such as a car horn, is coming from our right side, it will be heard slightly earlier and slightly louder in the right ear.

Our brain can use these subtle differences to create a kind of map of space, improving our awareness of where we are and how we are moving. Obviously, other senses such as vision contribute as well. At the end of the day, our senses are what enable us to interact and position ourselves within the world around us.

From a quality-of-life perspective, everyday activities are easier and more enjoyable when all our senses are working well together. When one sense isn’t working well, there is more pressure on other senses to try to pick up the pieces. This gets tiring, especially when we are trying to do several things at the same time.

Trying to hold a conversation on a bush walk when you have hearing loss and problems with balance because of a vestibular problem may not be possible.

Use of hearing devices such as hearing aids or cochlear implants can relieve some of the effort of listening, freeing the brain to better focus on walking and balancing.

The ear is a complex organ that should not be taken for granted. Protecting our ears from damage helps us stay connected with the world around us, not just by hearing but by maintaining our sense of balance and movement.

Not all ear problems are preventable, but there are ways of managing damage if it occurs. For example, hearing aids and listening strategies can help with hearing loss, and specific exercises recommended by a vestibular physiotherapist can assist with ear-related balance problems.