Audio-out stopped working on mavericks

I did have Audacity working fine. I just switched the audio out to an external USB device (which worked fine) then when I switched back to Built-in output the audio output stopped working properly.

When I try to play the track I just hear a loud popping sound, then silence. I then hear the same loud popping sound when I stop playback (or it reaches the end of the track).

I have tried restarting my computer and reinstalling Audacity but with no joy. I also tried clearing the config file.

I tried plugging headphones in and it works fine (still on Built-in output) but when I unplug the headphones it goes back to clicking.

The sound is working fine in all other applications I have tried.

Does anyone know how I can fix this problem? Please let me know if I can supply any information to help.

Audacity version is the latest (2.0.5).
OSX version: 10.9.4
2010 Macbook Pro

Many thanks.

MacBookPro’s may have weak connectors in the headphones port. Try taking the headphones in and out several times.

Macbooks on Mavericks turn off the audio subsystem after it’s been inactive. It is thought possible that Audacity cannot restart the audio subsystem once another application has played a sound then the sound system has turned off. Try opening Sound in the System Preferences, click the “Sound Effects” tab then uncheck “Play user interface sound effects”. Turn off the Mac and reboot. Open Audacity without playing sounds in other applications. Can you hear sound in Audacity?

If the theory is correct then you could have some application launch at startup then loop silence continuously then the sound would never turn off. But that could drain your battery.

If none of that helps then you can try an older version of Audacity like 2.0.2 or 2.0.3.