This question already has an answer here:
- Disable Mac startup sound 5 answers
How can I get my Macbook Pro Retina to not make that annoying 'bong' chime sound when booting up?
You can always hold "mute" during boot up, but that gets annoying fast if you always want the sound muted. Older systems (OS X 10.6 and below) can use StartupSound.prefPane, but that no longer works on modern Startup Ninja claims to do this, and it does, but it suffers from a bug where it will always unmute the system volume on login, even if the volume was muted when you last logged out.
Is there a way to accomplish this?