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Originally Posted by DanDan  Intuitively I doubt that the phenomenon is of enough magnitude to have an audible effect in the world of small studios, and even if it did, what could we do about it? |
This is exactly the point. If air becomes nonlinear by a tiny amount at levels 20 dB higher than will blow out your ear drums, who cares?
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I am very interested in the topic of LF measurements., in particular the variability we are experiencing.
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Yes, but the most sensible explanation is traffic rumble from outside. Or a distant plane, or your own footsteps, or similar.
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I find Decay spectra a lot more informative than Frequency Response graphs. I definitely want Decay information down to 40Hz.
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I'm totally with you there. And I want to see to at least as low as the speaker's -10 dB point.
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The method ignores once- off events such as cars passing or whatever, probably the same as REW.
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REW does that too, but I've never tried it. I should! From the REW Help:
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If Sweeps is more than 1 REW uses synchronous pre-averaging, capturing the selected number of sweeps per measurement and averaging the results to reduce the effects of noise and interference. The pre-averaging improves S/N by almost 3dB for each doubling of the number of sweeps. Averaging is particularly useful if the measurements are contaminated by interference tones, whether electrical or acoustic, as they typically will not add coherently in the averaging and hence will be suppressed by the process
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one rarely sees consistent EDT figures at LF. Now why is that, and can we improve it?
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Beats me. But whatever the cause, it's not because rooms are nonlinear.
If John is still here, maybe he can chime in?
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when doing RT, they average several sweeps and each one is different. I have seen it.
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But not with a moving microphone as in a reverb lab, right?
--Ethan