Problems in Reverb Time with measures

[Andrés Lazarillo]

Hello!!! I have been reseased a measurements in a Control Room and i can see that there is a inconsistance in differents measures in Reverb Time. Can somebody help me? I release the measurementes the same day but change the reverb time in 73hz. REW V5.20 Beta 53

The day before this measurements

Can be a Bug in the program?

Thank u very much.

 

[John Mulcahy]

Extracting the decay time of resonances through modal analysis requires a very high signal-to-noise ratio in the measurement and is sensitive to even small changes in the environment or mic position, especially if there are very closely spaced resonances as seems to be the case in your results. To examine changes in the low frequency decay it is better to use the RT60 decay graph.

 

[Jean Ibarz]

I agree that your signal to noise ratio is probably not enough to correctly estimate the decay time.

If the same audio interface is used as audio output and audio input in your measurement setup, you can try to increase the length of the sweep to the maximal value.
If a different audio interface is used as audio output and audio input (for example, your input comes from a numerical signal gathered from a USB microphone...) then you can try to increase a little bit the length of the sweep, but knowing that the longer the measurement signal, the higher the risk to introduce phase artifacts in your measurements. But for decay analysis, this shouldn't be an issue....
Adjusting your input gains may also improve your SNR.