Teams have tried a number of different ways to get the lower half of the face into the act with VR. That includes, and I’m quoting directly here, “a tiny robotic arm that could flick a feather across the lips or spray them with water.” They’ve also largely ruled out a piece that directly covers the mouth -- VR users ultimately didn’t like the sensation of having both their eyes and mouths covered at the same time, which, fair enough.
Ultimately, a team at Carnegie Mellon University settled on a much more practical method of offering added tacticity: ultrasound waves. A system developed by researchers at the school attaches a device to the bottom of a headset, sending the waves down toward the lips to create a kind of haptic sensation.
The technology operates similarly to the way hardware makers create virtual buttons on devices. The added twist here, however, is that ultrasound waves are capable of traveling through the air. They can only do so for short distances, but it’s enough to make the journey from the bottom of a VR headset to wearers' mouths.
The device utilizes 64 transducers arrayed in a curved configuration, which mix constructive and destructive amplification to vary the effect.
So, all of this presents the big question of why. Before you go getting any ideas, the end goal here is the same as with any VR peripheral: increasing immersion. The team cites ideas like raindrops, wind and, god forbid, a virtual bug crawling across your real lips. Among other things, the team notes that the mouth is a prime target because -- like the hands -- there’s a lot of sensation.
"You can't really feel it elsewhere; our forearms, our torso -- those areas lack enough of the nerve mechanoreceptors you need to feel the sensation,” says co-author, Vivian Shen.
Results of immersion will vary. Turns out things like cobwebs don’t work great, because it doesn’t make sense to have that feeling localized to the face. Ditto for a drinking fountain, because feeling the sensation without the actual water isn’t particularly convincing. Nevertheless, the team is continuing to iterate on the product, and working to make it smaller and lighter.
"Our phased array strikes the balance between being really expressive and being affordable," Shen says.