Laptop connected to TV via HDMI but no sound

Hello,

I have a Vaio NW150J laptop connected to my Samsung 530 LCD. I get video but no sound.

I've tried right clicking on the speaker icon and going to playback devices but the only thing that shows up is the laptop's internal speakers.

I also went to Computer > Properties > Device Manager > Sound, Video and Game Controllers. It said the HDMI cable was enabled. I tried disabling and re-enabling but that didn't work. Then I tried disabling the internal speakers and rebooting. Still no sound.

When I connect to my old Olevia the video and sound both work without any problems.