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Analyzing IR Measurements


Mark Oakley:
Hi Folks;
I've been using SMAART (v7.5.3) for almost 4 years now and have taken the Operators Fundamentals class twice. I'm pretty good with the RTA/Spectrograph and Transfer Function measurements as I do them all the time. We covered Impulse Response in my first class, but this is the first time I've had to do a measurement.

A friend of mine won a contract to do acoustic treatment to a room that we work in. This room is known for its long RT60, so he wanted to do some IR measurements before and after treatment. I've been reading the manual and practicing taking measurements in my studio the last few days so that I would be ready for today's measurement session. My studio is about 17 ft. x 24 ft. with a 12 ft. ceiling. I wacked two pieces of plywood together as my Impulse and found that I had an RT60 of 400 ms.:

The 5 Level marker widgets all seem to be in their proper place and the readout in the top-right corner makes sense.

After measuring the room today (the Symes) with the same plywood, the result looked like this:

While the ETC and Spectrograph look good, the 5 widgets and readout don't make sense. This room (untreated) has an RT60 of 3 seconds. Should I set the widgets manually?

I also took 4 short (5 ms.) Pink Noise bursts as a single measurement (Dual Channel) spaced 7 seconds apart and would like to Average them. The manual (p.142-143) says that this is possible but doesn't explain how to do this. Anyone know?

-thanks, Mark

(-also posted on the Rational Acoustics Forum)


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