After editing a one-hour podcast, I add the intro and outro music. At this point, playback becomes unusable, as it is accompanied by deafening static. This buzz does not get exported, so I can still export the final MP3 that listeners will hear, but it makes it difficult to QA the final cut while in Audacity.
I recorded my latest experience with this issue here:
I’m using Audacity 2.0.6 in Mac OS X 10.9.5.
-Ken
This is a known issue. It has been fixed (we hope!) in the latest alpha builds, leading up to the release of 2.1.0 later this month.
You could help us out by downloading and installing the latest nightly from the top of this list:
http://www.audacity.homerow.net/index.php?dir=mac/&sort=date&order=desc
and telling us if this cures your problem.
You can put it in a separate folder inside Applications (perhaps call that folder Audacity-alpha) so you can keep the stable, release version separate.
When you added the intro and outro music, did that create some tracks with “white space” at the beginning? “White space” means areas in a track where there is no audio, not even silence.
– Bill
Bill,
Oops! Sorry for not checking the fora to see if this was a known issue. 
I’d searched on a few keywords, but apparently not the right ones. My bad.
I did make sure none of the tracks started with silence, as that proved a workaround for a previous issue I was having.
I just downloaded Audacity 2.1.0-alpha-Jan 3 2015 and am unable to replicate my issue with this build. Looks like it’s been fixed. Thanks!
-Ken
Not a problem.
Thanks for trying it out and reporting the results.
– Bill
Hi Ken,
You actually reported the issue before and it was one of your projects you kindly posted that helped us find the playback problem. 
Can you please double-check in 2.1.0-alpha that the exported files are OK? In your previous project you managed to save the distortion in the exported file so that it could be heard even on Windows (and still can, even in 2.1.0-alpha builds). It’s not clear that we have fixed any problem there may be in rendering data to disk, so please check.
Gale
Hi, Gale —
Ah, I thought my previous report was a different but related problem.
I was able to use Audacity 2.0.6 to export my podcast without the static heard in the YouTube video above.
-Ken
OK, thanks. Please let us know if you encounter any more problems with playback or export in the upcoming 2.1.0 release (it will be a few weeks yet).
Gale