I was talking with someone last night and encountered something I didn't have an answer to.
Consider a PC with a graphics card (eg. an NVIDEA GeForce...) that has a HDMI output as well as analog/digital outputs.
Consider a TV which can receive sound and video from another device (eg. DVD player) via the HDMI input.
Now connect the PC and the TV together via the HDMI cable - is the sound from the PC played back on the speakers in the TV ?
Normally a monitor with speakers has two cables to the PC, a video (analog or digital) and a sound cable.