Today Facebook rolled out an annoying addition; a ding sound when you get a new notification; I found this to be unnecessary so this is how you remove it.
Click on the little gear icon in the top right corner of Facebook and click on ‘account settings‘
Click on ‘notifications‘
Click on ‘view’ on the ‘Notification sounds’
Uncheck the box for ‘Play a sound when each new notification is received’ then click ‘Save changes’
There you have it; a quick and easy way to stop the annoying Facebook Notification sound.