[Archived phorum post from squ1.com v2 by clarice]
Hi everybody,
I have some doubts about acoustic modelling can you help me please?
1) When do I assign the upper planes as a roof, when do I assign it as a ceiling?
I am a little bit confused about it because I did the acoustic tutorial and in the model called "simple theatre .eco" the upper planes are assigned as roofs whereas in the model called "reverberation time.eco" the upper planes are assigned as ceilings. Is there any acoustic difference?
2) When do I assign an object as a ceiling when do I assign it as a partition?
In the tutorial model "simple theatre.eco" there are a sloped internal surface inside the theatre assigned as ceiling and several suspended vertical surfaces assigned as partitions. Why aren't they assigned differently, I mean what are the differences in terms of acoustic behaviour?
4) Internal vertical surfaces which in real life would be built as walls (such as the one in the stalls) have to be modelled as walls or can be assigned as partitions?
I think I didn't get the role of partitions in acoustic modelling.
Apart from that, I couldn't figure out if it is necessary to link objects in the zone in order to perform an acoustic analysis, that is, establish parent/child relationships. In the tutorial examples there are no links but in my model they seem to be necessary as aparently the rays and particles are "leaking" from the zone.
I'm a bit puzzled can anybody help me, please?
Thank you in advance!
Best regards,
Clarice
Re: acoustic modelling
[Archived phorum post from squ1.com v2 by Andrew]
Hi Clarice,
To answer your questions:
1) For geometric acoustics, element types don't really matter (except for voids which are assumed to be acoustically transparent) - you could make all your surfaces windows if you wanted, as long as all the acoustic properties of the materials were correct. The Roof/Ceiling distinction in the model is mainly for future thermal functionality - however they are used in the Part-L calculations when checking allowable U-Values and to determine the exposed roof area in rainfall collection calculations.
2) & 3) As above - doesn't matter.
4) Important to make distinction here between geometric and statistical acoustics. Either way though, there is no need to link objects other than those that belong 'inside' other ones - for example voids or windows inside a wall.
In geometric acoustics (rays and particles) zones don't matter. Rays are 'leaking' out of your space simply because there must be holes in it through which they can pass. If you make your space geometrically 'watertight', it doesn't matter what zones the surrounding objects are on.
In statistical acoustics, however, the reverberation time is determined by counting up the total surface absorption and volume of each zone. This means that, to have your results make sense, each thermal zone must represent an individual fully enclosed space (basically one zone per room). This way ECOTECT can calculate the volume of each room and give a valid RT.
I know its a bit complex, however the sheer range of different calculations ECOTECT needs to be able to do means that sometimes they have to be approached slightly differently.
Regards,
Andrew
Dr. Andrew Marsh
Square One research Pty Ltd
Re: acoustic modelling
[Archived phorum post from squ1.com v2 by clarice]
Once again thank you Andrew,
I found a micro hole in my zone just after posting this message and when I fixed it there was no leaking anymore.
About the zone, I supposed exactly what you explained so I considered each room a zone. But I assigned each element type as if I was modeling for thermal calculation A bit laborious but with no interference in the results. Good!
Regards,
Clarice