AFMG Network Forum

Grzegorz · Member

Hi, I am a beginner in the program and I want to model the grid ceiling as in the picture in shopping centre.

https://www.google.pl/search?q=openwork+grille+ceiling&biw=1548&bih=881&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiNxbuGt_XNAhXMESwKHV_kBqgQ_AUIBigB#tbm=isch&q=+grille+ceiling&imgrc=RQu4xPBTeBN0jM%3A

Please tell me how it should be done. How to model the surfaces like that.
thanks

AFMG Frank Siegmann · Member

Hi Grzegorz,

I would suggest to ask the manufacturer for sound absorption coefficients.

Then you can create a corresponding wall material in EASE, which can be used as ceiling material in your EASE project.

Frank Siegmann
AFMG

thomas · Member

Hi,
it depends on what is above the grid and on the sound transmission coefficient of the grid. Do you have speakers above the grid, or absorber, or a huge empty volume without absorption?

If there is "a lot of" absorption above you can model the ceiling as one face with alfa = alfa(absorbent material)*tau(grid) [tau: sound transmission coefficient].

If there is a huge empty volume above and the sound transmission coefficient of the grid decreases considerably in the frequency range you're interested in, then there is no way to model it in an appropriate way. (At least I don't know a way)

If the sound transmission coefficient is very high in the interesting frequency range, you can approximate it with a little aborption on the (real) cealing (alfa approx. (1-tau)).

With speakers above: depends on what kind of speakers in what distance to the grid pointing in what direction (angle to the grid). Can't give no general response.

kind regards
thomas

Grzegorz · Member

Thanks,
Speakers will be below this grid ceiling facing to the floor. Above this ceiling there is about 60cm empty volume with concrete. I decide to model the ceiling as one face with absorbent material for concrete and scattering 15%. What do you think ?
Speakers:
http://dnh.no/speakers/cap-15wt-390.aspx

Kind regards
Gregory