Not asking how to change the volume, asking how to detect the actual volume (not the set 100 volume) of music/sounds. I wouldn't even know where to look, anyone have any idea? does flash even detect the actual volume output? So when the volume is 0 (e.g. maybe at the end of a song) the ._alpha is 0, so all I need is a variable for the output volume of a song.
with as3, you can approximate what you want by using the SoundMixer's computeSpectrum() method. you would enable fftmode and sum the absolute values to get a volume approximation that you would then need to normalize.
with as2, it's not practicable.