Virtual reality headsets, by dint of their design, give the impression that they are primarily visual devices. They look like extruded sleeping masks, after all. But appearances can be misleading. Indeed, as Jaunt’s Adam Somers told The Verge’s Mona Lalwani, “We consider audio to be 50 percent of the immersive experience.”

Immersive audio–binaural, to be specific, is not surround sound. Repeat that out loud ten times and we can proceed.

What, then, is binaural audio? The short version is that it’s audio that recognizes the distance between your ears. If something happens to your left, you not only hear it more loudly in your left ear (that alone would be surround sound); you also hear it after a delay in your right ear. Binaural audio, then, captures what each of your ears would hear if they were in an alternate location. This is achieved by recording sound with two microphones placed on the ears of ‘dummy head’. The Verge’s article has a great audio graphic you can use to experience binaural audio. You should give it a try. Like all 3D-sound, it requires that you use headphones.

As VR becomes more accessible, binaural audio will likely become more common in games. Its use, however, is not unheard of. In 2003, Terraformers, a game for the sighted and blind, earned an Independent Game Festival award. Using 3D sound, it allowed players to build space colonies without seeing them. (Terraformers is now available for free online.) In a similar vein, the iPhone game Papa Sangre turns your screen black. Its horror comes from being able to hear monsters around you.

That games for the blind or sighted, and games without video, can use binaural audio to remain navigable speaks to the medium’s potential. Imagine, then, what it could do when combined with visuals. As Apollo Studio’s Jean-Pascal Beaudoin told Lalwani: “If a sound is clearly coming from your left, and you turn your head 90 degrees to look in that direction, you now expect that sound to be located right in front of you. If it isn’t, and it’s still at your left, chances are you’ll be pulled out of the experience before you even realize it.”

H/T The Verge Image via DarioD