Field Story
Standing Waves Haunt the Control Room
A TV studio monitoring room had an 80 Hz standing wave causing a 16 dB peak at the mix position and a 12 dB null 0.8 meters behind it. Engineers were making incorrect low-frequency mixing decisions. RTA and room mode analysis confirmed an axial mode between the front and rear walls. Bass traps in the rear corners and a slight EQ cut at 80 Hz flattened the response to within 4 dB.
TV StudioPhase Analysis per ISO 3382-2
TL;DR
Phase analysis in ordinary rooms per ISO 3382-2 reveals the modal behavior that dominates the low-frequency acoustic response. In smaller rooms, room modes are more widely spaced and more prominent, making phase analysis particularly informative. Each mode produces a characteristic 180-degree phase rotation that is visible in the transfer function phase response. SonaVyx phase display helps you identify these modal signatures, understand how they affect reverberation uniformity, and plan measurement positions to avoid modal nodes where phase behavior is most extreme and RT60 measurements may be unrepresentative.
Phase in Small Room Acoustics
Ordinary rooms per ISO 3382-2 are typically smaller than performance spaces, placing the Schroeder frequency higher and making individual modes more audible and visible in the phase response.
Modal Phase Signatures
- Below the Schroeder frequency (often 200-400 Hz in ordinary rooms), individual modes dominate
- Each axial mode produces a 180-degree phase rotation centered on its resonant frequency
- Tangential and oblique modes add additional phase features at higher frequencies
- The density of phase rotations increases with frequency until the statistical region is reached
Position Selection Using Phase
- Measure the transfer function phase at candidate receiver positions
- Positions with extreme phase behavior (rapid rotations) are near modal nodes
- These positions may give unrepresentative RT60 values at those frequencies
- Select positions with more uniform phase behavior for ISO 3382-2 measurements
Phase and Absorption
Adding absorption changes the Q factor of room modes, which broadens the phase rotation. Well-damped rooms show gentler phase transitions than untreated rooms with high-Q modes.
Common Mistakes
- Ignoring phase data when selecting ISO 3382-2 measurement positions
- Interpreting statistical-region phase variations as meaningful features
- Not recognizing modal phase signatures at low frequencies
SonaVyx Workflow
View phase in the SonaVyx transfer function. Measure RT60 with the RT60 tool. Capture IRs with the IR tool. Check levels with the SPL meter. Predict room behavior at AcousPlan. Follow the room analysis workflow.
Standard Reference
ISO 3382-2:
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Last updated: March 19, 2026