I was studying the effectiveness of a head-mounted device to stop motion sickness in driverless cars when something unexpected happened. One of the participants in my experiment reported that her tinnitus had dramatically improved, she scored 100% for motion sickness susceptibility so was of interest even with the additional confounding effect of tinnitus.
Both motion sickness and tinnitus are linked to hearing and the inner ear, so it’s not uncommon for people who suffer from one condition to suffer from the other. Motion sickness happens when there is a mismatch between what the eyes are telling the brain and what the inner ears sense as motion (1).
In a car, this means that if you look down at a phone, a newspaper or a stationary object, your eyes are telling your brain that you’re not moving. But your vestibular system (the organs of balance in your ear) are telling your brain that you are moving.
This is the reason that having a good view of the road ahead and looking at the horizon to anticipate future motion prevents sickness. What your eyes see matches what you sense.
The head-mounted vibrating device I was investigating lightly vibrates just behind your ear. In the lab, it is known that this method reduces motion sickness (2). I wanted to know if it worked on real roads in driverless cars when people are facing forwards and backwards using a convenient wearable device.
We know from an earlier experiment that facing backwards in a driverless car causes a lot of motion sickness – more than trains – and may limit the number of people who use driverless cars with seats that face in this direction (3).
For the experiment, we recruited 24 volunteers all of whom were highly susceptible to motion sickness. The device we asked them to wear has four vibration levels. Half the volunteers (the control group) had the device set to the lowest vibration (level one), and half had it set to level three (the experimental group). Level 3 is the effective vibration level for motion sickness reduction.
The test lasted about 15 minutes with people getting sick after only six minutes while being driven around an urban route at normal speeds. The vehicle we used was a modified minivan with seats that faced towards the rear window, like many future driverless vehicle concepts.
The volunteers completed a search-and-find puzzle to make sure that they all looked down and not out the windows.
The device did, indeed, help those who became sick during the experiment. The extra vibrations on level three meant that people took nearly twice as long to become sick under the same conditions as the control group and commented that they recovered quickly when on straight roads. This means that for people who are highly susceptible to motion sickness, a journey could be 12 minutes long with the device, compared with six minutes without the device, before the person felt nauseous. The motion sickness findings will be detailed in a future scientific journal.
As I mentioned, one of our volunteers has tinnitus. She described the condition as constantly hearing a cricket chirrup. For her, the condition is a torment, especially when she is at home and it is quiet. For a tinnitus sufferer there is often no quiet time.
I applied the vibration device to the volunteer’s head and set it to level three. After the initial surprise of the vibration, she immediately noticed that her tinnitus had improved. Her beaming smile was something to behold.
Over many years, she had seen several doctors and specialists about her condition, but with no real progress. I don’t know why the device had this effect, only that it vibrates the inner ear, important for motion sickness and tinnitus.
I have since offered the device to other tinnitus sufferers (image below). They all have a similar smile. Some took the device home to use in the quiet where tinnitus is perceived at its worst. Afterwards, they don’t want to give the device back.
The device is comfortable to wear. Indeed, after a minute or two, people forget that they are wearing it. It is not noisy; the vibrations are below what we can hear. In fact, I had to ask for people to hand them back from the motion sickness experiment, they didn’t know they were still wearing them.
Although this is only anecdotal evidence, it was a real privilege to see those tinnitus sufferers experience some relief from their condition. The device is being developed further for motion sickness, vertigo and tinnitus. It is hoped that this information generates further research by others within the field of hearing / vestibular dysfunction. I have finished the research for my PhD, this however I feel should be continued with active tinnitus researchers