Improved Sound Control System
Mainly style comments:


var SB = {muted: false, previousVolume:1}: you should have whitespace after your last colon.
Math.pow(v,2): you should have a space after the comma.
In the following four lines, you should have extra whitespace in between your brackets:



function globalVolumeChange(v){ globalVolume = Math.pow(v,2);}
function globalStop(){liveSounds.forEach(function(snd){killSound(snd)});}
function globalPause(){ liveSounds.forEach(function(snd){snd.pause();}); }
function globalGetLive(){return liveSounds.slice();}




if( snd.src !== match ) return;: you should wrap this in curly brackets, as it can have undesired effects
You should avoid having extra space in your if-else statement brackets like in the point above, and in a few different places.