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Mapping
PostPosted: Fri Aug 11, 2017 3:30 pm Reply with quote
charles
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Joined: 23 Jun 2017
Posts: 9




Hi guys,

I'm trying to map an outdoor area which has oil tanks, buildings etc. on the site and I want to map the SPL across the site and between the buildings etc. The site is quite big therefore a bit slow to do the calculations and I got the impression something was not quite right, so I produced a small test model.

I have two rectangular walls separated by 1m and two loudspeakers aiming in toward the walls so that the area in between the walls is shadowed. The results do not seem to be what I would expect, the walls are set as steel and I would expect EASE to calculate the reflected sound between the walls, it doesn't. In fact with both loudspeakers set to Max the SPL range is shown as 89.10 - 78.22. If I set one of the loudspeakers to "all off" I get exactly the same SPL range, so it's obviously not working! Mapping is "Total SPL 2D" Shadow is on.

What am I doing wrong? I can email the packed project if required.

Thanks in advance.

Charles.
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PostPosted: Wed Aug 16, 2017 10:34 pm Reply with quote
Bruce
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Joined: 19 Apr 2005
Posts: 424
Location: Minneapolis, MN, USA




Please send the EASE Packed Project to support.

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Best Regards,
Bruce C. Olson
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PostPosted: Mon Aug 21, 2017 7:26 pm Reply with quote
Agustín Arias
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Joined: 10 Apr 2013
Posts: 28
Location: Caseros, Buenos Aires, Argentina




Hi Charles!

EASE will map full attenuation (0 dB) behind any "barrier" between the speaker and the receiver area.
The only way to calculate an approximation is doing a "Mapping with reflections" (or a reflectogram, but that would be to much for this study),

So, using the small model that you sent me, EASE will calculate a mixed mapping, with standard (equations) and with reflections (rays). The rays will be those that travel from the speaker, hit the box faces (may be several time, like bouncing between the boxes) and finally reach the audience area. So:

> Be sure that all the faces of both boxes are not ABSORBERS because if so, the rays will be fully attenuated.
> In the EASE Eyes module, go to Mapping > Standard with reflections
> Set an Area resolution (Patch Size) of 0.50. Check the map with shadow.
> Check Mirror image impacts and set an order of 8 and run the calculation.

When finish set z-view and see the differences between Direct SPL (0dB between boxes) and Total SPL.

So, you must play with the differents parameters in order to reach good results for you "big" model. For example, increasing area resolution will produce more acurrate results, but also the calculation will consume more time.

IMPORTANT: these results, in the real life, have to be considered as approximations!!! Becuase there will be a (small) sound from the boxes (or tanks) due to its attenuation is not 100 %.

_________________
Eng. Agustín Arias
Environmental Protection Agency, Buenos Aires, Argentina
Ottobre & Ottobre, Acoustical Consultants, Buenos Aires, Argentina
e-mail: agustin.arias@outlook.com
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Mapping
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