I have this issue when connecting my MacBook Pro Late 2010 on my Samsung TV Monitor via HDMI there is no sound coming out only picture. Alternativly when I'm using my dualboot Windows 7 installed on the same machine the sound works as it should via HDMI on my TV monitor. I have try everything and i've come to the conclusion that it's a built-in option that is not available in this version of the MacBook Pro Late 2010 (7,1) Is there a way to fix this issue without needing to buy additional hardware?
Using "Audio MIDI Setup.app" in the /Applications/Utilities/ folder, under the Window menu, select "Show Audio Window".
This will give you a list of input and output devices.
Select HDMI then right-click. A menu should then appear giving you the options to
Update: I learned the Macbook in question has a mini DisplayPort connection. I then found a link to a Griffin Mini DisplayPort to HDMI w/ Audio on the Apple Store which specifically says it works with the mid-2010 13" Macbook Pros.