Continuing the discussion from Computer Monitors:
(This looks like a topic hijack so I am replying in a new topic …)
Possibly you have not configured your computer to output sound via HDMI - or for somewhat old computers possibly your computer is not even capable of that.
Please mention what operating system and version you are running and what make and model of computer and what make and model of monitor.
Please confirm that the computer is connected to the monitor via HDMI.
