I have taken measurements over several days, and the levels do not seem consistent. I turn off the computer (MacBook Pro) between measurement sessions. After starting REW and checking that my preferences are good, I always check levels with the SPL meter. The results will vary as much as 5-8 dB on pink noise across boots, but are pretty consistent, measurement to measurement, after a start up. The waveform shapes across boots are very consistent for any given channel, but the levels are not. If I were to do a vector average of multiple measurements across boots, I believe the results would be inaccurate because of the variance in the levels.
I suspect the culprit is not having a calibrated SPL meter. Is there a recommended procedure to calibrate the SPL meter? Alternatively, is there a way to play the pink noise at a known level and tell the meter 'this is 70 dB'?
The only other device I have is an analog Radio Shack SPL meter, but it does not show digital values: it has a needle that sweeps from -10 dB to +6 or so.
Thank you, in advance, for any help you can provide...
Ron
I suspect the culprit is not having a calibrated SPL meter. Is there a recommended procedure to calibrate the SPL meter? Alternatively, is there a way to play the pink noise at a known level and tell the meter 'this is 70 dB'?
The only other device I have is an analog Radio Shack SPL meter, but it does not show digital values: it has a needle that sweeps from -10 dB to +6 or so.
Thank you, in advance, for any help you can provide...
Ron