The fact that we have two ears on opposite sides of our head provides us with directional hearing to determine where a sound comes from. While we have two nostrils though, we can't smell in stereo to find the source of an odor. Now, University of Chicago engineers have demonstrated a small electronic device that clips on your nose to imbue you with directional smell. It stimulates the trigeminal nerve that reaches into your septum with electrical current. Evan Ackerman writes in IEEE Spectrum:
You'd think that the way to mimic a stereo smell with this kind of device would be to stimulate one side of your nose differently than the other side, but remarkably, it turns out that you can generate stereo smell sensations (as well as smell intensity sensations) using only electrical waveform variation. The wireless, battery-powered device uses magnets to keep itself attached to the inside of your nose; it can detect when you inhale, and then uses electrodes to stimulate your septum. The current implementation communicates with external sensors, and this system works so well that completely untrained people can use the device to localize virtual smells, following electrically-induced virtual odors around a room.
The real question, of course, is what does it actually feel like to have this thing in your schnoz? Apparently, it doesn't feel like electricity in the nose or anything like that—it's actually smell-like, somehow. We asked Jas Brooks, first author on a paper being presented at CHI this week, to try and explain:
Describing this sensation with words is a tricky endeavor. The sensation our device produces can feel like a "tickling" or "sting," not far from that of wasabi or the smell of white vinegar, except it is clearly directional. Meaning, participants were able to understand if this sensation meant the "smell" source is to your left/right/front even without any training or explanations of any sorts. The actual "quality" of the sensation varied across the range of what the trigeminal nerve usually senses (e.g., some stimulations felt tingly like the wasabi, while others felt like pressure or even warmth in a nostril), which again suggests we are really hitting the trigeminal nerve with our electrical stimulation. Moreover, we're actually really excited about the fact that we seem to be able to trigger the quality of those trigeminal sensations too, e.g., perhaps we can create different qualities for these "smells" by only changing the waveforms.
"Digital Nose Stimulation Enables Smelling in Stereo" (IEEE Spectrum)