Immersive Audio: Measuring a 360-Degree Sound Field
With immersive systems such as L-ISA (L-Acoustics), d&b Soundscape, and Meyer Sound Spacemap Go now widely deployed on tours and installations, traditional left/right measurement approaches are no longer sufficient. Immersive systems are multi-channel, object-based audio engines, and must be measured as such.
The Moving Source Challenge
In a conventional stereo or LCR system, the phantom centre is fixed and predictable. In an immersive system, it is not. Audio objects can be positioned dynamically across the loudspeaker array, meaning the perceived source location can shift depending on the listener’s position.
As a result, the microphone position for measurement is critical. A single mic position optimised for left/right balance tells you very little about spatial accuracy across the audience. The goal is to maintain phase coherence and consistent arrival behaviour across the listening area, often referred to as the “golden zone.”
Object-Based Measurement, Not Bus-Based Thinking
Immersive systems render discrete loudspeaker objects, not fixed mix buses. Measuring them as if they were grouped left/right arrays is a conceptual error.
Best practice is to measure individual loudspeaker objects or small logical groups, verifying:
- Time alignment between adjacent sources
- Phase consistency through the critical frequency range
- Predictable summation behaviour where objects overlap perceptually
The objective is not maximum summation everywhere, but stable localisation cues wherever an object may be rendered.
Practical Strategy in Smaart
Use a multi-channel TF workflow to verify phase and timing alignment between adjacent or overlapping loudspeaker objects. Measure each contributing speaker or object channel against the same reference signal, and compare traces for deviations that could cause localisation blur. While Smaart does not visualise the immersive scene itself, this method ensures objects sum predictably and maintain spatial clarity across the audience.
The Takeaway
Immersive audio does not remove the need for measurement discipline; it demands more of it.
This is the difference between an immersive system that merely surrounds the audience and one that accurately places sound where it belongs. You basically have to treat ist like separate “stages”.
Historical context:
Delta-Stereophonie: Early Experiments in Spatial Audio
In 1987, the Palast der Republik in East Berlin used a system called Delta-Stereophonie, developed by Dr. Wolfgang Ahnert. It was an early attempt at multi-channel, object-based audio, designed to place sounds dynamically across the hall.
- The system allowed moving “phantom centres” and spatialisation of individual sources.
- Meyer Sound UPA-1A speakers were used, driven through a combination of analogue and early digital processing.
- The manual setup was performed by Jim Cousins using a SIM II system, ensuring careful calibration of levels and phase.
- His work was closely monitored by the Stasi, highlighting the political as well as technical significance of the project.
While ambitious for its time, Delta-Stereophonie provided important insights into phase relationships, spatial coherence, and object-based audio, lessons that continue to inform modern immersive audio design.
Smaart is excellent on its own, but most users find they get much more out of it after some structured training. That’s where our seminars come in. At TZ Audio we run practical seminars, both online and in-venue. We offer seminar-only or full “all you need packages” including software & hardware. It’s simply the fastest way to become comfortable and confident with the measuring a sound system.
If you’re in Norway, Sweden, Denmark or Iceland – or elsewhere – we offer is online seminars and traveling to Norway is a valid option too of course. We’re here if you have any questions about the software or upcoming seminars.
Thanks for reading!