We’ve all felt it before – whether it was when we spun around too quickly on an office chair as a child or if we simply stood up too quickly after being seated for a while, dizziness is a pretty common occurrence. But did you know that for some people, certain sounds can cause this same feeling?
New research has discovered why some people experience dizziness when they hear particular sounds. The congenital inner ear condition known as semicircular canal dehiscence affects about 1 in 100 people around the world and can cause vertigo as a result of specific sounds, changes in pressure, or even coughing. While the condition has been known to the medical profession for quite a while, the cause of the vertigo was a mystery – until now.
In a joint study at the University of Utah, the Johns Hopkins School of Medicine, and the University of Mississippi, researchers have uncovered new information about how semicircular canal dehiscence actually works. That being said, while the new study explains how the condition causes vertigo, it wasn’t the first to discover the condition – in fact, researchers have long known about semicircular canal dehiscence’s effects on the human body.
In a normal ear, the organs responsible for balance and hearing are encased in solid bone. But, in 1929, Italian biologist Pietro Tullio, discovered that even a small hole in that bony enclosure can cause increased sensitivity to specific acoustic sounds within the inner ear semicircular canals.
These sounds, like a sustained noise from a musical instrument, or a high-pitched conversation can cause the eyes to rotate in a reflex that would normally be used to stabilize an image during head movements. Usually, this reflex is important for giving us a clear visual image even if we’re moving, but if the signal from the inner ear is inaccurate, then the eye movements don’t follow the image properly and can cause dizziness symptoms similar to what we experience when we’ve had a bit too much to drink.
This dizziness can also cause nausea and a loss of balance in just a few seconds if the right noise is played. Plus, the effects of this dizziness can linger with a person for tens of seconds to even minutes after the sound has stopped.
Although we know quite a bit about how this condition affects the body, it wasn’t until this most recent study that we actually understand how sound can cause the balance organs in the ear to send incorrect messages to the brain.
To learn more about the processes involved in this condition, the researchers monitored the neurons and the motion of inner ear fluid in toadfish. It might seem odd that scientists would study fish to learn more about humans, but it turns out that toadfish inner ear balance organs are quite similar to those in our own ears.
What The Research Tells Us
The question still remains as to how sound can cause someone to be dizzy. Apparently, when we hear sounds, they cause mechanical waves in the fluid within the semicircular canals of the ear. In a normal ear, this fluid will move about whenever the head moves, triggering a counter rotation of the eyes to stabilize the image in the retina.
For people with a tiny hole in their semicircular canal, certain tones can cause the inner ear to create waves, even if the head isn’t moving, thereby sending an incorrect signal to the brain that the person is moving their head, even when they’re not. This reflex makes it feel like the world is spinning, thus resulting in the dizziness and nausea associated with semicircular canal dehiscence.
Luckily, there are surgical procedures available to repair the hole in the semicircular canal, so people with semicircular canal dehiscence can once again live without this often debilitating vertigo. If you find that you often experience bouts of noise-induced vertigo, reach out to your hearing healthcare professional – a tiny hole in your inner ear just might be to blame.