Depending on your choice to tick or untick the check box, the startup chime will be either turned on or off respectively. This setting can be changed any number of times, and it’s a good little feature that Apple decided to add, as there was a bracket of users who didn’t really like the startup chime and preferred a silent boot procedure.
Also, while you are in the sound settings, you can also decide whether you want to turn on or turn off other sounds across the system, and these too can be changed any number of times.
