I have a bunch of different audio recordings in WAV format (all different instruments and pitches), and I want to “normalize” them so that they all sound approximately the same volume when played.
I’ve tried measuring the average sample magnitude (the sum of all absolute values divided by the number of samples), but normalizing by this measurement doesn’t work very well. I think this method isn’t working because it doesn’t take into account the frequency of the sounds, and I know that higher-frequency recordings sound louder than lower-frequency sounds of the same amplitude.
Does anyone know a good method for measuring the loudness of a sound?
Root Mean Square is often used to estimate the loudness of sound files. This is because a sound that is very loud might not be perceived that way if it is very short. Also remember that power increases exponentially with the square of amplitude.
The audio geeks at Hydrogen Audio know a ton about this stuff…check out their free Replay Gain software. You may not need to do any programming at all.
EDIT: Included comment feedback on power vs. amplitude.