You are unable to get any sound via your HDMI connection to your Mac when using a Mini DisplayPort or Thunderbolt adapter. This may have occurred after upgrading to the Lion operating system.
- Check the device is selected as it may not work automatically:
- Click the Apple icon in the top left of the screen.
- Click System Preferences.
- Click the Sound icon.
- Click the Output tab.
- Click on the correct device.