would be around 89.0 db.
89dB would be SPL (Sound Pressure Level = acoustic loudness), not a digital level. There is no calibration between dB SPL and dBFS (digital) because there are many variables, including the fact that everybody has a volume control. But, there is a direct correlation… If you lower the digital level by 3dB, the acoustic level will also drop by 3dB.
89dB is the ReplayGain reference, and there IS an algorithm for calculating the ReplayGain level from a file and there is a [u]ReplayGain Plug-in[/u] for Audacity. Of course, that’s not necessarily the true SPL unless you’ve calibrated your system with an SLP meter. And once you’re calibrated you can’t touch the volume control or get closer or farther from the speakers without messing-up the calibration.
Now, what if audacity had their own “db checker” feature?
There are several options:
The Amplify effect will indirectly give you the peak dBFS level. Amplify will default to whatever gain or attenuation is needed for 0dB peaks. For example, if amplify defaults to +3dB your peaks are currently -3dB. (You can cancel the effect if you just want to check peak levels without changing anything.)
The [u]ACX Check Plug-in[/u] will give you the peak, RMS, and A-weighted dB levels.
The 3rd-party [u]dpMeter 3[/u] will give you several measures including LUFS.
I know that it recommends, when choosing to amplify, the db you should choose to amplify down or up… but I’ve noticed that it’s quite horrible in doing so, and I never trust it to be correct.
Amplify works perfectly! If you “Amplify” by -6dB (attenuate) the levels will drop by 6dB. (That’s ALL of the dB measurements… peak, RMS, LUFS, etc.).
You do have to “be careful” about [u]clipping[/u]. (That’s why I used an attenuation example instead of an amplification example.). Many digital formats are limited to 0dBFS peak., You can’t go over and if you try you’ll get clipping (distortion). Audacity itself won’t clip, but your DAC (digital to analog converter) is limited to 0dBFS you can get distortion.