## Chris Whealy - calculators

Tools for acoustic calculations -

### Chris Whealy - calculators

Some valuable and rather unique calculators:
http://www.whealy.com/acoustics/index.html

New version of Porous Absorber spreadsheet
http://forum.studiotips.com/viewtopic.php?t=1639

1. Control Room Calculator
This spreadsheet is designed to calculate the basic acoustic properties of a rectilinear control room.
These properties include:

• Basic geometric properties (Surface area, volume, edge length etc)
• Reverberation time (RT60) calculated using various formulae (Sabine, Eyring, Arau etc)
• On-axis reverberation times.  This will help you avoid designing a room with flutter echo.
• Lowest possible resonant frequency
• Schroeder transition frequency
• List of resonant modes up to the eighth oblique mode
• The standard deviation of modal distribution
Practical use, further description and care to be taken described on the site.

2. Porous Absorber Calculator
This spreadsheet is designed to predict the absorption curve of various designs of porous absorber.

In order to get the best results from this spreadsheet, you will need to know (or at least have a rough idea of), a value called "flow resistivity".  This is a measure of how much resistance the porous material offers to the flow of air through its fibres.  This is rather a obscure value, but it is essential that it is in the correct range as it is of fundamental importance to the absorption calculations.
In the spreadsheet, there is a sheet called "Flow Resistivity" that explains the importance of this value, what it means, and how it can be derived.

The spreadsheet will calculate absorption for the following types of absorber:

• Rigid backed porous absorber
• Slotted panel absorber
• Perforated panel absorber
• Microperforated panel absorber (integrated: May 5, 2005)
For each type of absorber, the absorption curve will be plotted with, and without an air gap.
Also, for the slotted and perforated panel absorbers, two plots are calculated concerning the position of the air gap.
It can either be between the panel and absorber, or between the absorber and the rigid backing.

Practical use, further description and care to be taken described on the site.

divinely-inspired
Eric.Desart
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