AFMG Network Forum

logandodson · Member

I am attempting to modify a theater to hit a certain RT using the Schroeder calculation, but do not want to spend 30min on each test calculation for the space. I figured using the Local Decay feature under Mapping would give a more accurate estimate than the general sabine equation, but i am getting some strange results.

My sabine time is at 0.87s, the local decay time shows as 1.2s, and the full Schroeder calculation shows a 0.49s. I would expect the Local Decay time to be closer to the Schroeder outcome instead of being even higher than the sabine. With this outcome, I cannot use the Local Decay feature to estimate what my Schroeder outcome will be.

Has anyone else experienced this? Or know what might be causing it?

Bobbyed · Member

[quote="logandodson"]I am attempting to modify a theater to hit a certain RT using the Schroeder calculation, but do not want to spend 30min on each test calculation for the space. I figured using the Local Decay feature under Mapping would give a more accurate estimate than the general sabine equation, but i am getting some strange results.

My sabine time is at 0.87s, the local decay time shows as 1.2s, and the full Schroeder calculation shows a 0.49s. I would expect the Local Decay time to be closer to the Schroeder outcome instead of being even higher than the sabine. With this outcome, I cannot use the Local Decay feature to estimate what my Schroeder outcome will be. best sex dolls

Has anyone else experienced this? Or know what might be causing it?[/quote]

Inaccurate absorption assignments or missing surfaces
The local‐decay mapping tool in programs such as EASE or similar requires that all surfaces (walls, ceilings, floors) are properly defined with accurate absorption coefficients. If some surfaces are missing, excessively reflective / low absorption, you’ll end up with a “worse” (longer) decay in the mapped region, hence the 1.2 s value.

passivsrty · Member

This is an interesting problem, and it sounds like you're diving deep into acoustic modeling! It's definitely odd for Local Decay to deviate so much, especially being higher than Sabine. Typically, Local Decay should offer a more refined view, potentially closer to Schroeder's detailed calculations. It almost makes you want to Block Blast through the parameters to find the culprit. Perhaps the boundary conditions or material absorption coefficients are interacting in an unexpected way with the local decay algorithm. Have you checked the frequency weighting for each calculation? That could be a significant factor.