Steam Audio
Last updated
Last updated
Steam Audio adds physics-based sound propagation on top of HRTF-based binaural audio, for increased immersion. Sounds interact with and bounce off of the actual scene geometry, so they feel like they are actually in the scene, and give players more information about the scene they are in.
The simplest thing that any spatial audio technology must do is HRTF-based binaural rendering. This refers to a way of recreating how a sound is affected by a listener's head, ears, and torso, resulting in subtle cues that allow you to pinpoint where a sound is coming from.
Steam Audio's implementation of HRTF-based binaural rendering has a very low CPU overhead; you can handle hundreds, even thousands of sources using a single CPU core. It also minimizes the frequency coloration of audio clips, while maintaining good localization.
Steam Audio simulates how objects occlude sound sources. In addition to the typical raycast occlusion that many game engines already support, Steam Audio supports partial occlusion: if you can see part of a sound source, Steam Audio will only partly occlude the sound. Steam Audio uses your existing scene geometry to occlude sounds, so you don't need to create special occlusion geometry just for sounds.
Reflections and reverb can add a lot to spatial audio. Steam Audio uses the actual scene geometry to simulate reverb. This lets users sense the scene around them through subtle sound cues, an important addition to VR audio. This physics-based reverb can handle many important scenarios that don't easily fit within a simple box-model.
Steam Audio applies physics-based reverb by simulating how sound bounces off of the different objects in the scene, based on their acoustic material properties (a carpet doesn't reflect as much sound as a large pane of glass, for example). Simulations can run in real-time, so the reverb can respond easily to design changes. Add furniture to a room, or change a wall from brick to drywall, and you can hear the difference.
In reality, sound is emitted from a source, after which it bounces around through the environment, interacting with and reflecting off of various objects before it reaches the listener. Developers have wanted to model this effect, and tend to manually (and painstakingly!) approximate sound propagation using hand-tuned filters and scripts. Steam Audio automatically models these sound propagation effects.
Steam Audio simulates sound propagation in real time, so the effects can change automatically as sources move around the scene. Sounds interact with the actual geometry of the scene, so they feel integrated with the scene.
