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How Does Your Brain Experience Virtual Reality?
3D audio, or binaural audio, is a technology where audio is recorded and played back in the same way that human ears perceive it. A lot of the technology is related to re-creating the doppler effect, which is the phenomenon where objects moving towards you are higher pitched than objects moving away from you, and it has to do with how sound waves move through space. When an object is moving toward you, each time a sound wave is produced its starting point is closer to you than the last one. By the time the sound reaches your ears, the waves are closer together, which results in a higher pitch. The inverse happens when the object is moving away from you: the wave is emitted further from the last one stretching out the space between them. which causes a drop in the pitch.
Since our ears are located several inches apart on either side of our head and pointing outward in opposite directions, every single sound reaches our ears at slightly different times. Even though it's fractions of a second, our brain can perceive these differences and geolocate the direction that the sound is coming from. The shape of our ears and head can change how we experience sound, too. The way sound traces the curves of an ears and travels through our skull can change how we experience sound, too. The way anatomy affects how we perceive sound is called head-related transfer function or HRTF. Without it, sounds tend to sound "flat". To replicate this requires creating two microphones shaped like ears and attaching them to a recording device that actually looks like prosthetic head.
While some of these systems can be used with regular headphones, some researchers are taking things a step further by making speakers that correspond with the shape of a person's head. The technology came out of Microsoft's labs and uses a sensor to scan a person's head and shoulders. The software creates a 3D model, learn their HRTF, and predict how sound would reach their ears. It also tracks the movements of the listener's head, so in a virtual reality setting, the sound matches the direction the person's ears are pointing and tricks them into thinking a sound came from a specific direction.
Surrounded by sound: how 3D audio hacks your brain (The Verge)
"For decades, binaural recording was a novelty, and overlooked for less technically demanding methods. But with the rise of virtual reality hardware like the Oculus Rift, Sony's Morpheus, and Samsung's Gear - systems dependent on realistic 3D audio to fully immerse their users - binaural audio is on the cusp of a renaissance."
Microsoft's "3-D Audio" Gives Virtual Objects a Voice (TechnologyReview)
"Headphones that make sounds seem to come from specific points in space could be the perfect counterpoint to virtual reality goggles."