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If your computer has no loudspeakers or headphones connected to it, sound should be coming from the system unit (the computer box). Most but not quite all computers have an internal speaker. If there is no speaker, there cannot be sound either! If you need sound, please make a service request to the helpdesk system and ask for headphones or speakers for the computer you use.
Youtube sound
Control Youtube volume and set sound on mute as follows:
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