Not too sure why you surf sites that play sound if you are already listening to something. It probably helps if we know what you looked at where you did not then find an icon, can you post a link ? Does this help * http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/soundscpl_change_system_volume.mspx This is more of an OS problem, rather than Firefox. Most keyboards will have a mute button. The Windows XP options will include sound settings and a mute option. You may find this useful if you have no mute key * http://www.howtogeek.com/howto/windows-vista/create-a-shortcut-or-hotkey-to-mute-the-system-volume-in-windows/ Whatever page you are on probably has a volume and mute setting, and an option to pause or stop sound. Firefox options may include disabling any add-on or plugin that is used to play sound, or using something like no-script. Note plugins may be disabled per site if it helps.