Mentions of 'adapters' and 'audio cables' suggest the problem could be that whatever connection you're using won't carry audio between those devices. Can you expand on exactly which ports, cables and intermediary devices you're using?
Do you have the audio cable connected to the TV's composite inputs ? I would imagine the TV will only accept audio and video via the same cable, so HDMI in this case. If you change the TV's input to the composite sockets, you'll get the audio and no video, presumably.
Does the MacBook not output audio over HDMI ? I'm not familiar with Apple products, but on a Windows machine, you would have to go in to the audio settings and select HDMI as the output for audio.