Annoying Sound Effect

I'm trying to figure out how to disable this annoying sound effect without disabling all sound effects from the game. And no I don't want to disable system sounds either (which I'm guessing is what this noise is coming from).

The effect I'm speaking of is where you press a skill that isn't ready yet or are too far from a target or invalid target or whatever. That annoying beepish sound that plays. I have this habit of clicking a skill multiple times so, just in case I lag or the button press didn't register, the skill WILL fire off. I'm talking after I press the 1 key, I will press the 2 key until that skill goes off. And inbetween this, all I hear is 'BOOP BOOP BOOP BOOP BOOP' and I'm wondering if there's a way to shut it off.

And please don't tell me to just 'stop spam pressing the key' because it's a HABIT and I have a reason for doing it. It isn't easy to break this.

Well, thats a system sound. So either you lose them all, or yes, you need to break that habit.

I tuned system sounds off, and believe me, you will get used to not having the rest. But this is so much nicer on the ears if you are a button mashing machine >_>;

You can actually perform actions quicker if you press the button when you see the cool-down finishing instead of mashing the button.