The latest version of Odeon has, hidden deep inside the material editor, a calculator that estimates the absorption coefficient of acoustic finishes. This quite neat and pretty well put together.
There are few graphic scale issues but overall it looks useful, in agreement with test data (for the 2 cases I’ve played with) and is quite handy (save and use).
Section 4.5 of the new edition of the Odeon Manual gives a decent amount of details.
Acoustic Research & Design Ltd 