Hi,
Open windows Control Panel, open Device Manager and open up Display Devices - make a note of the hardware listed here i.e. ATI, Nvidia or Intel.
Next, connect your notebook via HDMI to your Tv. Right click the speaker icon in the Taskbar and select Playback Devices. Left click once ( just to highlight the entry ) the HDMI Output that has the same name as your display adapter and then click the Set Default button - see if you now have audio through the Tv.
Regards,
DP-K