How do I disable the Mac startup sound?

The "bong" sound Macs make when starting up are very annoying. Although they serve a purpose as a POST confirmation, I'd rather not have it alert everyone in the room.

There are ways to either quiet or turn off the sound in OS X, but that's not something I currently have access to, nor am I willing to install.

Is there anything I can do?

Macbook 2006

Solution 1:

Late reply but:

1. Reboot with an OSX installation disc or Recovery HD

2. Start the Terminal

3. Issue the command:

   /usr/sbin/nvram SystemAudioVolume=%01
   

Solution 2:

I just now thought of this. I did a bit of research on it and I didn't find anything specific, but I think that you could disable it via rEFit boot manager.

I have rEFit on my iMac to swtich between OSX and Windows 7 and it has all sorts of tools for boot options and partitioning. I think you might be able to do it through it since it uses the EFI or "BIOS" directly and you should be able to install it through Ubuntu according to the site. I'll do some more searching around and testing if I can and edit my answer as it applies, but for now here is the link for rEFit:

http://refit.sourceforge.net/

EDIT:

rEFind as suggested in comments. rEFind is currently maintained:

http://www.rodsbooks.com/refind/