iFlyChat JavaScript SDK fires an event named 'current-user-sound-update' whenever sound notification is switched on or off for current user. You may bind to this event in following manner:
iflychat.on('current-user-sound-update', function(message) {/* your code here - message object contains information about if sound is switched on or off */​});
Here message is a JS object with following properties:
id
sound
Possible values of sound:
true - Sound is on/ Unmute
false - Sound is Off/ Mute