How to scare the * out of people with VR
Three dimensional (3d) audio has been utilized in games and movies for some time. In traditional surround systems, the speakers are located only at the level of the ears. 3d audio systems add new height channels that allow sounds coming also from above. This brings a new level of immersion into the sound scene. Due to the fixed speaker — listener distance, however, it is not possible to trick the listener to hear sounds from very close distances.
In Virtual Reality, headphones are used to deliver the audio content. With headphones and head tracking provided by the VR headset, 3d audio is provided by filtering the sounds through Head Related Transfer Function (HRTF) and rotating the sound scene according to the head tracker. This way the listener can sense the sounds coming from all directions: front, back, left, right, above and below.
For obtaining the most realistic virtual audio experience, the HRTF should take into account personal differences in how sounds from different directions reach the ear. That is strongly dependent on the individual anatomy of ears. If your individual anatomy closely matches the one that has been used in the HRTF, the sense of directions can be very convincing and the sounds react in a natural way when you turn your head. When the sounds come up close, the magic is broken because the HRTF does not work with sounds coming from distances smaller than a few feet. Oculus’ Lauren Betbeder wrote a great post about how this “near field” effect is approximated in their new Audio SDK.
So now we are slowly getting to the how to scare the crap out of people. Just imagine the possibilities VR storytellers are going to have with this new way of making sounds come from very near, right behind your back. Maybe you are in the VR world, wandering alone in a gloomy forest, and some strange sound is grabbing your attention. You slowly get closer to see what it is, feeling curious and anxious at the same time. Suddenly, you hear a whisper right behind your back, instantly turn around but there’s no one there… and the plot thickens.
We at IDA Audio have also been developing ways to make sounds coming both from far away and very near sound natural and realistic. Here you can test yourself a “real virtual barber shop”, where the sound of a barber clipper is virtualized and going up your neck. So nothing too scary, yet. For virtual positioning of the barber clipper we used simulated near-field HRTFs. And to be precise, my own near-field HRTFs. How does this sound for you?
In case you are interested in near-field HRTFs, our CTO Tomi Huttunen just presented a poster at International Conference in Spatial Audio in Graz and we released a high resolution near-field HRTF example. You can find all this from idaaudio.com/downloads. Happy HRTFing!