i myself went through a lot of headaches and google research, wondering why my MBP had no audio through the MDP while my brothers did. Especially when we got it around the same time. After a bunch of surfing on the web i came up with this list. Before doing random trouble shootings and buying a bunch of different adapters, first check the model of the product.
If you don't know the specific model go to "about this mac" then click the "more info" look under "Model Identifier (you should be in Hardware Overview)"
Here's the list of laptop models that support audio pass-through via MDP
MacBook Air 11" Model 3,1
MacBook Air 11" Model 4,1
MacBook Air 11" Model 5,1
MacBook Air 13" Model 3,2
MacBook Air 13" Model 4,2
MacBook Air 13" Model 5,2
MacBook 13" Model 7,1
MacBook Pro 13" Model 7,1
MacBook Pro 13" Model 8,1
MacBook Pro 13" Model 9,2
MacBook Pro 15" Model 6,2
MacBook Pro 15" Model 8,2
MacBook Pro 15" Model 9,1
MacBook Pro 15" Model 10,1
MacBook Pro 17" Model 6,1
MacBook Pro 17" Model 8,3
If you do not see your model, you might be out of luck. Hope this helps out people on this thread.
I've been around and around trying to solve this- another thread led me to a very simple solution:
From another user (Fee Fi):
This issue can sometimes be resolved by opening the Audio MIDI Setup application (located in Applications/Utilities) and changing the output setting to 44 KHz (44100.0 Hz).
1. Open the Finder
2. Applications> Utilities> Audio MIDI Setup
3. Click the drop down menu after Format and choose any of the options
When I looked at my displayport adapter specifically it was set at 96 HZ
Changing it to 44 immediately restored sound via displayport for me
For those with older Mac models that don't support sound output through mini displayport, you can purchase the Mini Displayport Male | Thunderbolt® and USB Male/Toslink Audio to HDMI® Female Converting Adapter from monoprice.com to pass both audio and video through a single hdmi connector.
"This adapter connects to a female Mini DisplayPort to provide video, a USB output to provide power, and includes a mini TOSlink to TOSlink cable to connect from the 3.5mm (1/8 inch) digital audio output of your compatible Mac® to the TOSlink input on the adapter in order to deliver true digital audio and video output to the adapter's female HDMI® port. All you need to add is a male to male HDMI® cable to connect from the adapter to your television and you're ready to view AND hear movies, games, or anything that's displayed on your Mac" from monoprice.com
Hope this helps. I have a 2008 MacBook Air and ordered this.
I had the problem where I could select HDMI as a device for sound output, but no sound would come out through the HDMI cable. It wasn't working with my LCD monitor, nor my Sharp TV.
Solution was to restart the program generating the sound (in my case, Chrome) after selecting HDMI as device for sound output.
Nice. I had to change the Midi output from 48000 to 44100 and that did the trick (Panasonic TV).
Never would have found it without your Midi tip. Thanks!
Also bought an extra HDMI adapter because I didn't think the first one worked. With this change both do. Well, no biggie, good to have one extra I guess