3D audio and ambisonics
Getting started working with spatial audio
What is it?
3D audio, or spatial audio, uses sound objects to place sounds around you in the environment. The effect is similar to gaming, where sounds from characters appear to come from the direction they appear from.
Ambisonics captures sound in all directions using a special microphone, and allows it to be 'decoded' to play back on a variety of outputs. We render the sound as binaural in real-time, rotated according to the listener's orientation, ready to be played back on headphones.
ECHOES enables spatial audio by using its existing system to place sound triggers (or Echoes) which then play sounds (Elements) which have fixed GPS coordinates. These sounds are then spatialised around the listener, creating a 'real' environment in which you can approach and walk around sound objects.
How do I experience it?
To experience the full force of our spatial audio, you need headtracking. To understand more about headtracking, read here.
Currently 3D audio/ambisonic support is only available on
- iOS in the production app (although support is still in beta)
- and android via the beta version of the app.
To access the beta version of ECHOES on android, visit the Google Play store listing and sign up for testing.
When you do the walk, it will only work when downloaded (it should prompt to do so).
It will prompt you to use headtracking. Currently there are three options (two on android):
- Using the onboard compass (phone sensors). This will spatialise using the phone’s compass, so point the device where your head is pointing.
- Using the Thingy:52 IoT bluetooth prototyping device. Attach it to a hat or the headband of a pair of headphones
- Using the Apple Airpods Pro headphones, which support spatial audio (iOS only).
How do I create 3D sounds (sound objects)?
For 3D sounds, you can either:
- Select 'Add a 3D sound element' when adding an Element. It'll have the '3D' switch turned on already, or
- use your existing Elements: just enable the 3D button on the Element.
Each sound has its own 'marker' which indicates its virtual placement in real space. You can move these. Bear in mind that if the sound is physically far from you when you trigger the Echo, you likely won't be able to hear it.
Each sound will appear to come from its location. You can add multiple sounds per Echo, and have them at different positions, and these sounds will be spatialised around you, giving you the appearance of a 'sound' environment that changes as you move.
How do I upload ambisonic (360°) files?
For ambisonic sounds, select 'ambisonic' when creating an element.
Don't switch the type to ambisonic after creating a 'sound' otherwise it will fail when you try to play it in the app.
Once you've created an ambisonic Element, then you can upload a first order, ambix channel order (wxyz) file (wav or aiff) and it will convert it.
Currently HOA (2nd/3rd order) is not working (although we're working on it).
Can I spatialise binaural sounds?
Binaural sounds are already encoded as spatial audio. You cannot rotate them or 'spatialise' them, much in the same way you cannot create a 3D model from a photograph.
If you use a binaural sound as a 3D 'sound object' the binaural effect will be lost and the sound will be played back as mono. For this reason it is best to use binaural sounds as they were intended: as stereo playback over headphones.
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