Introduction to Spatial Audio
Spatial audio encompasses all techniques for reproducing or creating the impression of sound in three-dimensional space.
Definition
Spatial audio goes beyond stereo by adding:
- Horizontal surround: Sound from all directions around the listener
- Height: Sounds from above and below
- Distance: Perception of depth and proximity
Brief History
| Era | Advancement |
|---|---|
| 1881 | Clément Ader's Théâtrophone (early stereo) |
| 1931 | Alan Blumlein's stereo patent |
| 1970s | Quadraphonic sound |
| 1990s | Dolby Surround, then 5.1 |
| 2010s | Dolby Atmos, object-based audio |
| 2020s | Immersive audio democratization |
Key Concepts
Sound Source
A sound source is characterized by:
- Position: Where the sound comes from
- Directivity: How it radiates in space
- Spectrum: Its frequency content
Listener
The listener perceives sound through:
- Two ears: Enabling binaural localization
- Head and body: Causing acoustic shadowing and diffraction
- Brain: Interpreting acoustic cues
Reproduction System
The system converts an audio signal into sound waves:
- Speakers: Convert electrical signals to acoustics
- Room: Influences sound propagation
- Processing: Adapts content to configuration
Reproduction Approaches
Channel-Based
Each speaker receives a dedicated channel:
- 2.0 (stereo), 5.1, 7.1, 7.1.4...
- Simple, standardized
- Limited flexibility
Object-Based
Each sound is an object with spatial metadata:
- Dolby Atmos, MPEG-H
- Adapts to any configuration
- More complex production
Scene-Based
The entire soundfield is captured/encoded:
- Ambisonics
- Format-independent
- Requires decoding for each system
Applications
| Domain | Use |
|---|---|
| Cinema | Immersive film experience |
| Music | Spatial mixes, immersive concerts |
| Gaming | 3D environments, VR/AR |
| Live Sound | Concerts, theater, events |
| Installations | Museums, exhibitions, public spaces |
Introduction to Spacelite
Spacelite from DAM Audio uses a hybrid approach:
- Input: Stereo (channel-based)
- Processing: HSR distributes spatially
- Output: Flexible multichannel (up to 16 channels per bus)
This allows transforming existing stereo content into immersive spatial experiences.