I don't know how to do this, but wonder if anyone else does.
I often lock the doors while walking away from the car, but without any audible noise, I am stuck locking again to hear the horn beep, which is too loud.
Not sure about the original poster's car, but mine "chirps" once on locking, and twice on unlocking. I think the manual calls it "answer-back" and its a feature of the advanced keyless entry system - it can be changed from the head-unit settings (when parked.) According to the manual, the default volume setting is "medium", and it can be changed to "off", "low", or "high."
Believe that setting is only available with the 'advanced keyless entry' feature that is part of the GT Tech Package. But our 'lesser' CX-5's still get the horn beep when - as I and others have pointed out - you click the lock button twice....