[Archived phorum post from squ1.com v2 by milan]
Hi,
As a novice in cad modeling, i have a couple of questions related to acoustic design:
1. related to the width of an object/wall: say i was modeling an already existing situation, and I would like to assign a reflector completely bonded to a ceiling (not suspended). Should i just insert a panel into the ceiling as a child object? In that case, how am i to know whether this plane was inserted above or below the ceiling? Once inserted, does it replace the part of the ceiling it covers (in that case it changes the acoustic properties of the whole ceiling, Right?)?
If i choose to draw a new plane just below the ceiling, tag it as a reflector, i get an error message saying i have modeling errors as the two ceiling planes overlap. Moving it downards creates a new path for the rays, correct?
2.adding absorption coefficients together: if i modify the width of a certain material with defined absorption coefficients, how do i calculate the coefficients for a new configuration?
3. If i create a new material by adding different layers, how do i account for absorption coefficient changes? Does ECOTECT acount for any layers that are not direclty exposed to rays?
For instance, if i have a brick wall, air cavity and a gypsum panel, will all three elements be Acounted for in the calculations?
And if i was to apply paint to that panel, that would Influence both the absorption and the diffusion of sound...
4. If i choose to design a wall with all of its dimensions (height/width/depth), how do i assign Material properties to each plane? I mean, how do i approach the width factor? If i assign a certain width to each plane, which direction is the width accounted for? Half the specified width in each side?
5.say i have a cavity that i would like to fill with a certain material, mineral wool for example. Should i just draw a zone with defined absorption coefficients?
6. Say i was trying to model a mechanical resonator by creating a cavity covered in absorbing Material in the wall and covering it with a plywood panel. Is that possible at all?
I am familiar, to a certain point, with the issues mentioned above, i would just like more explanation on the extent to which ECOTECT can model them, as i found the help file a bit short
On description. The way it seems to me as a newcomer in ECOTECT modeling (and cad modeling altogether) is that, in the acoustics domain, ECOTECT is primarily an architectural tool that serves the purpose of setting the base for a further investigation by an acoustics consultant which will further determin the design details.
I was more involved in the measurement procedures (even though lacking proffesional measurement microphones), and would like to invest more time into modeling rooms, but i guess the approach i am sort of used to in acoustic preditcion and interpretation just brings too many uncertanities that should be avoided in geometrical simulations. I need to know where the limits are so i don't really stress too much over things that are either unavailable in ECOTECT or not of concern at all .
Maybe some of you doing modeling could send some modeled rooms i could check out and get more familiar with the ECOTECT approach... are any of you modeling in Catt Acoustic or odeon? I have the limited demo versions so i can't really grasp the full potential, but would like to hear some comparison with ECOTECT features. Thanks...
Milan
A tip for people modeling acoustic environments...acoustical solutions have posted a bunch of materials/elements on their web site in autocad format. you can download the drawings and spec sheets with absorptin coefficients and short instalation instructions for each element.
Re: wall properties and related
[Archived phorum post from squ1.com v2 by craines]
» Should i just insert a panel into the ceiling as a child object?
Yes. The panel feature is for specifying variations in material properties within the same plane -- so if your reflector is flat to the ceiling but is made of another material you would use a child panel inserted into the ceiling object.
» how do i calculate the coefficients for a new configuration?
You should really use values for the entire material composition, prefferably from a source that you are familiar with or can apropriately reference etc. so as to ensure they are reasonable numbers.
» how do i account for absorption coefficient changes?
» Does ECOTECT acount for any layers that are not direclty
» exposed to rays?
Not sure what you mean by this really... In ECOTECT the material definition is applied to the single object and the effects of the material are considered as a whole composition so to speak.
» If i choose to design a wall with all of its dimensions
» (height/width/depth), how do i assign Material properties
» to each plane?
For an acoustic calculation you shouldn't really do this as the extra geometric information is redundant and will cause your calculations to be unrealistic.
Acoustic modelling in ECOTECT is very similar to thermal modelling (pretty much identical in fact) in that you only really need to define the geometric internal volume of the space and appropriately assign the material propertise for these internal surfaces.
» 5.say i have a cavity that i would like to fill with a certain material,
» mineral wool for example. Should i just draw a zone with defined
» absorption coefficients?
Not if you mean you draw a zone for the cavity... you just need to define the effects of the extra mineral wool material within the material properties for the wall object that uses it. So the effect of the wool is defined in the material not the geometry.
» Say i was trying to model a mechanical resonator by creating a
» cavity covered in absorbing Material in the wall and covering it with
» a plywood panel. Is that possible at all?
Not that I am aware of, but my acoustic knowledge doesnt extend that far so I will ask and get back to you...
» ECOTECT is primarily an architectural tool that serves the
» purpose of setting the base for a further investigation by an
» acoustics consultant
Kinda... we like to think of it as allowing the architect to get the majority of the acoustics right, from the start of a project, by ensuring the geometry is appropriate and not causing any problems that then need to be fixed by a consultant.
In the majority of instances if you can get the internal geometries of a hall / theatre etc. etc. right, you then dont have to deal with the issues of bad reflections or acoustic shadows etc. So I guess we see the acoustic aspects as a design tool for preventing acoustic issues.
But as well, if a consultant needed to retro fit reflectors or the like, then the visualisation and ray spraying would be ideal for ensuring the size position and angle worked well. you could then move on to different material properties for the reflector etc. and see the varying effects of those and which might be most appropriate.
» are any of you modeling in Catt Acoustic or odeon?
I heard somewhere that we might be adding an import/export facility for Catt Acoustic files... I will investigate this for you too though as I am not at all certain of this.
Hope all this helps you...
Regards,
Caroline
Caroline Raines
Square One research Pty Ltd
PS. any chance of when you add another post to our forum that you not use ALL CAPS and extra carriage returns ? ...I had to go through your whole post and remove all the CAPS etc. as my eyes where pretty much dropping out trying to read it