On my old laptop, which ran Snow Leopard, I had it set to not play system sound effects. As far as I remember, all I did to achieve this was go to System Preferences -> Sound -> Sound Effects tab -> uncheck "play user interface sound effects". This worked well - my laptop never made a sound unless I explicitly told it to.
I have done the same thing on my new El Capitan laptop, and this does seem to have disabled some sound effects, but nevertheless my computer still makes a "bonk" sound in some situations. For example:
- In XCode, it happens if I press Shift-CMD-Z when there is nothing left to redo.
- In Finder, it happens if I try to paste a file into a folder for which I don't have write permissions, or if I press CMD-S while a Finder window has the focus.
- A few times it's happened seemingly at random, probably due to me accidentally triggering a trackpad gesture.
This runs the risk of embarassing me in a meeting, giving me an unwelcome surprise if plugged into an amplifier, etc. Is there a way in El Capitan to completely disable all sound effects, except for the ones generated by games, music programmes etc. that I explicitly ask for?