Verification method for acoustic field uniformity in reverberation room

 
1、 Basic verification method
1. Multi point sound pressure level measurement method
-Layout rules:
-At least 6 measurement points should be evenly distributed in space (recommended cube with 8 vertices and center point), with a spacing of ≥ 1.5m.
-The height of the microphone is 1.2-1.5m (simulating the position of the human ear), avoid approaching the wall (distance ≥ 1m).
-Judgment criteria: The standard deviation of the sound pressure level at each point within 1/3 octave band bandwidth is ≤ 1.5dB (500Hz-4kHz frequency band).
 
2. Rotating diffuser method
-Equipment requirements: Install 1-2 sets of electric rotating diffusers (blade speed 1-5rpm) to disrupt the standing wave mode.
-Verification steps:
1. Static measurement: Close the diffuser and record the unevenness of the original sound field (usually with a low-frequency difference of ± 5dB).
2. Dynamic measurement: Repeat the test after turning on the diffuser to verify the diffusion effect (target: reduce the difference to within ± 1dB).
 
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2、 Advanced technical means
1. Acoustic camera scanning
-Technical principle: Generate sound field cloud maps by combining a 48 channel or more microphone array with beamforming algorithms.
-Output indicators:
-Thermal map of spatial distribution of sound pressure level (resolution 1cm × 1cm).
-Modal density analysis (verifying whether the normal modes overlap sufficiently).
 
2. Pulse response analysis method
-Test signal: Generate pulse sound using balloon explosion or electric spark sound source.
-Key parameters:
-The consistency (difference ≤ 10%) between early decay time (EDT) and reverberation time (T60).
-The smoothness of the sound energy attenuation curve (R ² ≥ 0.98).
 
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3、 Error Control and Calibration
1. Background noise correction
-Before measurement, it is necessary to ensure that the ground noise is at least 10dB (A weighted) lower than the test signal.
-Time window filtering is applied to the low-frequency range (<200Hz) to eliminate air conditioning vibration interference.
 
2. Equipment calibration
-The microphone array needs to be calibrated with a sound calibrator（ 94dB@1kHz ）Channel by channel calibration, phase difference ≤ 0.5 °.
-Verification of frequency response flatness of sound source (fluctuation of 20Hz-20kHz ≤ ± 1dB).
 
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4、 Application of cutting-edge technology
1. AI real-time optimization system
-Deploy deep learning models (such as CNN+LSTM) to dynamically analyze sound field data and adjust diffuser speed/angle.
-Case: Siemens' SmartDiffuser system, launched in 2024, reduces uniformity calibration time by 80%.
 
2. Digital twin verification
-Build a 3D sound field model based on COMSOL or VA One to simulate the effects of different diffuser layouts.
-Advantages: Reduce the number of physical debugging and support virtual calibration (such as spacecraft reverberation chamber design).
 

Summary: Technical iteration direction
-Full frequency coverage: Develop ultra-low frequency diffusers (<50Hz) to solve the uniformity problem of large reverberation chambers (such as wind power equipment test chambers).
-Automated authentication: storing blockchain certification test data to enable remote auditing by international standard organizations such as IEC.
 
If specific scenario plans are required (such as validation of car audio testing cabin), parameters can be provided for further customized analysis.