This video is showing you what to do to make sound on your TV when using Windows 7/8/8.1 via DisplayPort to HDMI.

I use Windows 10 just as a presentation, so don't worry, the fix is for Windows 7.
I did this on my laptop, ProBook 6450b, and it worked!

Driver download link: https://downloadcenter.intel.com/down...

Follow the instructions!