 Posted: Wed Feb 20, 2013 1:14 pm |
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| AFMG Pedro Lima |
| Forum Moderator |
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| Joined: 05 Jun 2010 |
| Posts: 269 |
| Location: Germany |
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| To people who is keeping track of this post:
"Hi Oscar,
There was only the EASE Project attached. Do you also have the raw measurement files? It would also be nice to know the location where they have been taken.
Well, there are a number of inconsistencies in your drawing. It’s likely that they are the cause for the unnatural RT behavior. I will try to point some of them here but you should understand that I cannot take a deep and through view to your project, ok? Also, it seems there are far too many details for an acoustical model. This would have as consequence a huge increase in the calculations times in general, especially for AURA and evaluations involving Ray Tracing. You must distinguish between an Architectural Model and an Acoustical Model. The second will typically have far less details, as you need to be straight forward in your analysis and be careful with the calculation times.
• You should only use Two-Fold faces for barriers or elements that you know will have both sides of the Face exposed to the sound. The pillars on both sides of your drawing should not be Two-Fold faces, as their internal area are not exposed to sound. This will also affect the total volume, as their internal volume would actually be subtracted. There are also other places with similar conditions.
• There are rooms other than the main room. This is critical. There are rooms above the main entrance of your church that there are not part of the main acoustical space. This will only increase the room volume and contribute negatively to your simulation. EASE is a program based on statistical acoustics assumptions and will not take into account transmission from one room to other. I could not be sure due to the high volume of details, but it seems this is also the case with the altar. This is especially important if Eyring and Sabine RT simulations are being performed other than AURA and Raytracing.
• There are Faces Coating the wrong Faces. The Coating Face should be Coated over the Face that is covered by it. Please refer to the EASE tutorial for more information about Coated Faces (Is Coat Of in its properties window). There are also Faces that are not being Coated, while they should. As the top rectangular windows nearby the entrance.
Oscar, it seems you are in the right way but there are still a lot of modeling issues that you must address before going on. Please allow me to advise you some extra literature to help in the process: Vorlander M. – Auralization, Fundamentals of Acoustics, Modelling, Simulation, Algorithms and Acoustic Virtual Reality.
I hope this helps.
Pedro" |
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| Posted: Sat Mar 02, 2013 11:41 pm |
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| Ron Sauro |
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| Joined: 29 Oct 2005 |
| Posts: 27 |
| Location: Elma, Wa |
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| I have been researching this for a very long time now and I think our research may help here.
1st... All of these simulation programs use the absorption coefficient for calculation of the total absorption of a closed room. In our research papers we have shown that area alone cannot be used to multiply the absorption coefficient to get total absorption...
The edge effect is the problem here... In these programs the assumption is made that an absorption coefficient cannot be above 1.0.
The way that absorption is measured does not support that theory.
It is not at all unusual to get coefficients way above 1.0.
This means that if a particular frequency is looked at that might have a coefficient of 1.7 and it is limited to 0.999 you are underestimating the total absorption of that surface by a very large percentage and there for will always over estimate the RT of the room....
My papers are on the front page of my website at
www.nwaalabs.com
Ron Sauro
NWAA Labs, Inc |
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