When you press a number key to bring up an item from the quickbar into the cursor, it does not play a sound. Keep holding the item in the cursor, then press a different number to bring up a different item from the quickbar into the cursor: That plays the sound. Any subsequent repetition of pressing a number will keep playing the sound, only the initial selection of a quickbar item via keyboard does not.
Extremly minor inconsistency in my opinion.
