AFMG Network Forum

ambupe · Member

i´m trying to fixed the parameters for the standard calculation in the room mapping window - standard with reflexions option.

I have two audience areas in my model. The first, bigger, has the height of a human ear approx.(1.68 m). The second, has the height of a human ear in the first floor when sitting (2.65 + 1.2 m).

I need the SPL direct and total SPL maps. When I display the results for SPL direct no error happens. But when i display the results for SPL total the result for the smaller one is anormal.

This audience area is above the loudspeakers, into a room, with walls, ceiling and floor, is enclosed. So I don´t know why the total SPL map shows a constant color in the audience area, that corresponds with a high level decibels. I don´t know the reason for that problem, and í can´t resolve that problem.

I read that audience areas can´t be above loudspeakers. But i don´t know why. I have 4 loudspeakers with diferents heights ( 1.25 m and 1.4 m) and I´m interested on that height. could be relating with??

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ambupe · Member

Red: audience areas. The bigger one (1.68m) and the smaller (3.85m) enclosed because is an office. In this case,all loudspeakers are activated.

https://mail.google.com/mail/?ui=2&ik=6546b03747&view=att&th=133f8fe3a0afd554&attid=0.1&disp=inline&realattid=f_gvnklrqq0&zw

When SPL direct is represented everything is normal:

https://mail.google.com/mail/?ui=2&ik=6546b03747&view=att&th=133f905f249787e8&attid=0.2&disp=inline&realattid=f_gvnkxnwv1&zw

But when SPL total is represented the level in the smaller area is so high, why?? is enclosed!

https://mail.google.com/mail/?ui=2&ik=6546b03747&view=att&th=133f905f249787e8&attid=0.1&disp=inline&realattid=f_gvnkw9r60&zw

Jim Mobley · Member

Ambupe,

The forum doesn't allow attachments and I really can't tell what your problem is without seeing the model. Please pack your project and send it to me and I'll have a look at it.

Please also include a step-by-step description of exactly what you are doing that leads to your question, and the results you expect to see.

ambupe · Member

ok, I have already sent the pack project. I hope you can help me with it, please!!

thanks a lot.

Jim Mobley · Member

I have not received any e-mails from you. Please try again.

ambupe · Member

that rare. I´ll try again to jim@renkus-heinz.com address.

Jim Mobley · Member

I still have not received anything from you. It is not being caught in a Spam or Junk filter, as I have checked them. You are not trying to send large attachments are you? We have a 5 MB file size limit, but packed projects are typically a few hundred KB at most.

Bruce · Member

Jim Mobley · Member

Of course, that's clear, but I'd like to see what else might be going on.

Jim Mobley · Member

Dear Amor,

I've looked at your model and you have several problems.

1) EASE can model one and only one acoustic space, you have a couple of smaller rooms with no connection to the main space. (I see that you have doors there, but the "doors" are closed with faces.)
2) EASE does not model transondance of faces; faces completely block sound transmission. (With Shadow Cast switched on.)
3) The loudspeakers are below the audience areas. As Bruce has already explained, areas map only on the top and loudspeakers must either be above the area or above the extended plane of the area in the case of sloped areas. Listener seats do not have the limitation that speakers must be above them, so you will see very different results mapping to seats rather than to areas.
4) In standard mapping the assumption is made that statistical acoustic metrics are valid, i.e. that the room has an even distribution of absorption and a homogenous reverberant field. Total SPL is the summation of the direct and reverberant fields, as the reverberant field is assumed to be constant throughout the room, it's value will not change anywhere in the model, regardless of the subdivisions you've made to the space. In your model, when mapping to areas, as the loudspeakers are below the areas, Direct SPL = 0 dB everywhere and as the reverberant field is assumed constant, total SPL at 1 kHz, 1/3 octave is 87 dB everywhere, with all loudspeakers on.
5) By making your interior partitions two-fold, you've "tricked" EASE into closing the room, but statistical calculations are still not valid for this condition.

To do the study you want to do, you must leave statistical acoustics and use one of the Ray Tracing computations, either Ray Tracing, Find Impacts or AURA if you have it. Due to the length of the required computations, I recommend that you compute to listener seats even in AURA. Keep in mind that you will still have the issue that EASE cannot compute transondance, however, if you "open" the doors, you can get an approximation of how much energy comes in through the openings.