I’ve always thought that start-up sounds on phones not only are annoying, but also pointless. Why would you want a phone to make a noise during boot up? There are two ways of disabling it, and one of them requires root access.
- To disable the boot sound on your Android device, you can install a tiny application called Silent Boot.
- Silent Boot provides the following workaround: it mutes your phone when you turn it off, which will disable the start-up sound, and restores your previous volume settings after startup.
- If you have root access, you can also try this permanent workaround described at xda-developers.