After years of using Windows XP, most people (including myself) got bored with the standard startup sound. This is the reason why, after a while, I chose to disable it. With the launch of Windows Vista, Microsoft wanted to bring a new startup sound. So they hired a team of 20 composers, sound designers, engineers, and developers to create the new Windows Vista startup sound. It took them 18 months and 500 entries from which the final sound was picked and embedded in Windows Vista.
Even though the new startup sound is pretty good, just like with any other new thing, it will become old after a while and people will get bored with it and will probably choose to disable it.
To disable it, you need to go first to the Control Panel and type the word “sound” in the search box.
From the list of search results, click on Change system sounds. The Sound window will open directly to the Sounds tab.
In the lower part of the window you will find the option called Play Windows Startup sound. Uncheck that box and the startup sound will be disabled.
Additionally, you can choose to disable the whole Windows Vista default sound scheme. To do that, select No sounds from the Sound Scheme drop box.
When you have finished making all the changes don’t forget to click the OK button.
How to disable or change sounds in Windows Vista
Disable the System Beep
Put the Volume Mixer icon back on your taskbar
Pimp My Windows Vista: How to change your sound scheme