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Old 24th March 2009, 12:33 PM   #1
Pulse-R is offline Pulse-R  Australia
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Default Modes and Nodes and Density - Acoustic Math help

I recently took in a light presentation about acoustics and treatments in small rooms.
The presenter demonstrated a handy-looking spreadsheet that when calculating room nodes, there was a subsequent function which determines the density, or such, for any given nodes.

Parameters I have so far:
Lx (length)
Ly (width)
Lz (height)
V (volume)
A (surface area)
Nx (modes of Lx)
Ny (modes of Ly)
Nz (modes of Lz)
Fn,n,n (mode frequencies, i.e. F[0,0,1];F[2,1,3];etc.) up to N=4
Fc (diffraction mode?Schroder frequency)
Rt60 (calculated from V, A and Fc)
dc (Rt60 distance)

and a dumb-looking graph

can anyone help me with a method to calculate the sound density at a given node's corresponding frequency?

thanks

Simon

(btw, this is intended as "research" for an interesting maths vs. reality for my in-car audio project)
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Old 24th March 2009, 06:49 PM   #2
Ron E is offline Ron E  United States
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I've been down this road, and there is not much useful you can calculate from these parameters - it all depends on how far you go.

All small rooms are bad regardless of modal density. Rooms with duplicate dimensions are really bad. Damp out early reflections, that is all you need to know unless you are building a studio.
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Old 25th March 2009, 02:58 AM   #3
Ron E is offline Ron E  United States
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If you don't wish to heed my earnest advice and forget about it, go here: http://www.silcom.com/~aludwig/
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Old 26th March 2009, 08:32 AM   #4
Pulse-R is offline Pulse-R  Australia
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Quote:
Originally posted by Ron E
If you don't wish to heed my earnest advice and forget about it, go here: http://www.silcom.com/~aludwig/
That looks good.. I'll get a cuppa and have a read.

Thanks
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