I've had some predictions of sound reinforcement performance done with EASE,
which include RASTI predictions. I am a bit mysitifed as the RASTI comes
in three different flavours, decribed as 3 octave analyses centred on 500,
1000 and 2000 Hz. To my understanding, STI and RASTI should be single
figure measures of a system. I think maybe what is happening here is that
some other measure is being taken and converted to RASTI via a formula. But
the figures for different frequency ranges are not identical and they can't
all be right.
I have also seen a paper from the AES 2002 conference in St. Petersburg, by
Ahnert, Feistel and Schmitz, on this very subject of EASE and RASTI, but
that doesn't help me as it also includes graphs showing both RASTI and STI
varying with frequency, without very clear explanation of the derivation.
Can anyone who uses EASE throw any light on this?

Signature
Tony Woolf
My e-mail address has no hyphen
- but please don't use it, reply to the group.
Tom Harper - 30 Nov 2005 01:12 GMT
Tony
I have a copy of the EASE 4.0 manual (Ease 4.1 Users Manual
By Acoustic Design Ahnert, Berlin.) that I pickup at a recent training
seminar. "Appendix A - Acoustic Formulae" of this document outlines all
of the formula used in EASE including the STI and RASTI calcs.
I can't find this manual on the website for download so I suspect that
you have to go to the training course to get it or buy it directly from
ADA. If you need I could print out the relevant pages and e-mail them
to you. But the whole manual is pretty good and worth getting if you
could buy it from ADA.
Tom Harper
Bruce - 07 May 2006 06:20 GMT
> Tonywrote:
I've had some predictions of sound reinforcement performance done
with EASE,
> which include RASTI predictions. I am a bit mysitifed as the RASTI comes
> in three different flavours, decribed as 3 octave analyses centred on 500,
[quoted text clipped - 3 lines]
>
> Can anyone who uses EASE throw any light on this?
Hi Tony,
I know this is an old question, but I've just joined the forum.
In EASE Standard mapping, RASTI is computed using a curve-fit equation
from a prediction of %ALCons. As %ALCons is calculated using the
Hopkins-Stryker form of equations using statistical measures there
can be significant variations from real world spaces where these
equations are problematic.
A better calculation of STI using the MTF calculated using the
Analysis Utility for Room Acoustics (AURA) module from a predicted
Room Impulse Response is the preferred method.
There is an EASE specific forum at
SDA Network that
you may want to check out.
Bruce - 07 May 2006 06:20 GMT
> Tom Harperwrote:
I have a copy of the EASE 4.0 manual (Ease 4.1 Users Manual
> By Acoustic Design Ahnert, Berlin.) that I pickup at a recent
training
> seminar. "Appendix A - Acoustic Formulae" of this document
outlines all
> of the formula used in EASE including the STI and RASTI calcs.
That Appendix is actually from Chapter 6 in "Handbook for Sound
Engineers" by Glen Ballou written by Dr. Wolfgang Ahnert.
Bruce - 07 May 2006 06:20 GMT
> Tom Harperwrote:
I have a copy of the EASE 4.0 manual (Ease 4.1 Users Manual
> By Acoustic Design Ahnert, Berlin.) that I pickup at a recent
training
> seminar. "Appendix A - Acoustic Formulae" of this document
outlines all
> of the formula used in EASE including the STI and RASTI calcs.
That Appendix is actually from Chapter 6 in "Handbook for Sound
Engineers" by Glen Ballou written by Dr. Wolfgang Ahnert.