I made a voice recording in Audacity 2.0.3 (dmg installer), amplified it a bit, and the audio sounded fine. Then I exported it as an MP3 file, and there’s no sound in the MP3 playback. I’ve done this dozens of times and have never had a problem before. Would you have any idea what’s causing this? Thank you.
The current Audacity version is 2.0.5: http://audacityteam.org/download/mac .
Where are you playing the MP3 where it has no sound?
If you used a USB recording device, unplug it from the computer.
You can check Mac audio settings in the “Sound” system preferences.