If the chime your Mac makes on bootup drives you batty, have no fear – it’s controllable. You can mute, turn down, or even turn UP your Macintosh startup volume using freeware utilities!
There are a few applications out there that will allow you to adjust the Apple startup noise, but only one (as far as I can tell) that will allow you to adjust the startup chime on Intel based Macs – Psst from mistatree will let you do it on your x86 Apple computer, and it’s easy to use too!
Psst is a universal binary that runs in OS X, meaning that it will run on PPC Macs, as well as the newer Intel Macs like iMacs, MacBooks, MacBook Pros and Mac Pros.
To install the program, simply download the DMG image file using Safari, Firefox or your favorite browser, and mount the image by double clicking it. After that you can copy the file anywhere on your hard drive and run the application by double clicking it. Adjust the startup sound to your liking and reboot to see the changes. You will notice the difference on bootup/startup – the startup chime should be less noisy or muted depending on how you adjusted it.