Field Story
The Dome That Made the Imam Speak Twice
A mosque with a 14-meter dome created a strong acoustic focus point 8 meters from the mihrab, causing worshippers to hear the imam twice with a 120 ms delay. Impulse response measurement clearly showed the focused reflection. Applying diffusive panels to the lower dome surface and a thin absorptive layer at the focus zone reduced the reflection by 14 dB, restoring clarity.
MosqueSpectrum Analyzer Measurement per ISO 3382-1
TL;DR
Spectrum analysis supports ISO 3382-1 room acoustic measurements by verifying source spectrum coverage and analyzing the frequency-dependent behavior of the room. The omnidirectional source used for ISO 3382-1 must produce sufficient energy across all octave bands from 125 Hz to 4 kHz minimum. A spectrum analyzer confirms this requirement is met before you begin capturing impulse responses. Additionally, spectral analysis of the room response reveals frequency-dependent absorption patterns that explain variations in octave-band RT60 values. SonaVyx RTA mode with octave band overlay provides the real-time spectral monitoring needed for ISO 3382-1 field work.
Spectrum Analysis in Room Acoustics
ISO 3382-1 requires that the excitation signal has adequate energy across the frequency range of interest. Spectrum analysis provides direct visual confirmation of spectral content and identifies deficiencies before measurements begin.
Source Spectrum Verification
- Verify that the source produces measurable energy in every octave band from 63 Hz to 8 kHz
- Check that no band is more than 10 dB below the average level
- For dodecahedron sources, verify spectral uniformity at multiple angles
- Pink noise should appear roughly flat on a per-octave display
Room Response Analysis
- Compare the room spectrum at multiple positions to assess spatial uniformity
- Identify frequency bands where the room adds or absorbs energy disproportionately
- Low-frequency buildup near walls indicates modal behavior
- High-frequency rolloff indicates air absorption and surface absorption
Background Noise Spectrum
Capture the background noise spectrum before measurement. This reveals which frequency bands may have inadequate SNR and where the INR requirement will be most difficult to achieve.
Common Mistakes
- Assuming pink noise has equal energy per Hz instead of per octave
- Not checking source spectrum at the measurement level (it may differ from maximum output)
- Using the spectrum analyzer with A-weighting when Z-weighting is needed for band analysis
SonaVyx Workflow
Use the SonaVyx spectrum analyzer for source and room spectral verification. Capture impulse responses with the IR tool. Extract RT60 with the RT60 calculator. Measure SPL with the SPL meter. Predict room performance at AcousPlan. Follow the room analysis workflow for structured measurement.
Standard Reference
ISO 3382-1:
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Last updated: March 19, 2026