[LAU] Room acoustic sound analysis

Russell Hanaghan hanaghan.osaudio at gmail.com
Sun Sep 13 18:57:30 EDT 2009


Hello LAU,

While I have not been active on this list in a long time, I have been 
watching from the side stage and it's nice to see the string of various 
information and experience still flowing thru the LAU community.

I'll get to my questions as they relate to the subject title in a sec 
but firstly, a little back ground on some significant changes I have 
going on and how they may relate to the furthering of open source audio...

I have left the corporate grind and world of regular income for purposes 
of pursuing my all time passion. I have not a pot to piss in nor a 
window to pitch it out of in terms of capitol and am largely doing it on 
faith! My core products are fretted instrument and amplifier / music 
related electronics repair, recording and demos, small PA system rentals 
and also working as a musician for hire, primarily doing my solo thing. 
In another post I will  speak to my dilemma of being unhappy using Sonar 
8 on Windows Vista and looking for some possible encouragement to 
consider going totally open source!

 I have rented a large warehouse type space (2600'sq) in the Nth Cali 
foothills and within there are several spaces dedicated to the various 
products I alluded to. The main room that we do live music in is a good 
size, approx. 30'w x 40'l with 17' ceilings. It's predominantly drywall 
and stud construction and also with a 17'x10' metal roll up door. It has 
a concrete floor with industrial carpet covering it. I have just 
described something of an acoustical nightmare, likely only topped by an 
aircraft hangar with corrugated iron walls and roof! :) We have been 
doing some live stuff thru a PA in this room and it's a sure fire way to 
reveal how the room reacts. The room produces some high freq (2k - 5k) 
boosts as well as some 150 to 400hz bumps. While I have implemented some 
baffles to reduce live high freq bounce, these only serve to deaden the 
room and not change tonal characteristics. How I go about changing the 
mechanics of the room will be dictated largely by economics but in order 
to assess this, I'm looking to to some spectrum analysis.

Has anyone set up a laptop and microphone and open source apps and 
performed this to some success? I need a tone generation source as well 
as an analysis tool. It needs some bias adjustment for mic and sound 
card inherent response I should think. That said, it does not need to be 
a perfect tool. If I can get some form of reliable, self referenced 
measurement, that would give me something more than the guess work I am 
currently using from my head and my ears.

TIA for your input and ideas.

Russell



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