Measuring RT60 of a huge hall

[ReDRuM]

Hello!

I'm wondering what would be the preferred method of measuring RT60 of a huge hall? Say RT60 = 5-6 sec.

And what would be the needed setup?

Would a loudspeaker (for good SNR) + REW + measurement mic + sine sweep method suffice? Then measure in different locations etc.

Or is there perhaps a reason why in such a space some other method (such as interrupted noise method) would be inherently more appropriate?

Thank you

P.S. - I just noticed that REW doesn't provide the actual RT60 graph... Only T20 and T30... So I should extrapolate the data for RT60 from T30 values? Is that "acceptable"?

 

[John Mulcahy]

T20 and T30 are RT60 values. If you are making RT60 measurements in a large space change the IR truncation setting in the Analysis preferences to make sure enough of the IR is retained for the decay to reach the noise floor. It may also be necessary to use a longer sweep (with a 256k sweep there are about 6 seconds of IR data after the peak before any truncation is applied). Sine sweep should work provided the speaker used can deliver sufficient power to get good signal levels at your measurement points.

 

[ReDRuM]

Thank you!