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My ETC measurements show some early reflections that need to be treated. I confirmed the location by using the blocking method with a temp. 4" OC 703 panel. Now the question is how thick the panel needs to effectively treat the reflections. The goal being -20db in the first 20ms. There's conflicting information about the thickness of material needed to treat early reflections (4 inch vs 1 or 2 inch).
Below are the ETC graphs with and without the temp acoustic panel. I also took some band limited measurements to determine what frequencies were involved.
ETC full/limited band comparison (freq. range and db reduction of 5.5ms ceiling reflection) with and without 4" temporary acoustic panel.
20-20khz -8.2db posted below
1k-2khz -11.5db
500-1khz -4db
20-500hz +1.2db
Based on the measurements above the 4" panel of OC703 provided no benefit below 500hz. What would be the justification of using a 4" panel in this situation?
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Below are the ETC graphs with and without the temp acoustic panel. I also took some band limited measurements to determine what frequencies were involved.
ETC full/limited band comparison (freq. range and db reduction of 5.5ms ceiling reflection) with and without 4" temporary acoustic panel.
20-20khz -8.2db posted below
1k-2khz -11.5db
500-1khz -4db
20-500hz +1.2db
Based on the measurements above the 4" panel of OC703 provided no benefit below 500hz. What would be the justification of using a 4" panel in this situation?
