Right now there is no official way to turn down the Google PAC-MAN Doodle off or to mute the sound, but here are few ways in which you can actually avoid or stop the PAC-MAN sound from annoying you. Please note that, these solutions might not entirely turn off the sound, but it may help nevertheless.
- Switch to using I Google (http://www.google.com/ig) for the next 48 hours instead of the regular Google homepage.
- Use your browser address bar to perform searches, works in IE8, Google Chrome, Firefox, Opera and Safari (Make sure your browser default search engine is Google).
- Use the search box in your browser to search.
- Stop using Google and try an alternative search engine for a day or two.
These are the things I could think of to get rid of the annoying Google PAC-MAN sound for time-being. However, if you have your own solutions, please feel free to add to this. I will update this post as and when a definitive solution for turning off the Google PAC-MAN sounds comes up.