There has been some effort to correct this. It's a combination of problems.
Overall instructions on how to correct this:
You need to use the console command ":audiobuff <value>" and set it to at least 2048. (replace <value> with 2048 or another, higher number.) If 2048 doesn't fix the problem, you can go higher, but as it dedicates RAM to the audiobuffer, it can cause some other issues if you get too high, such as lagging up the game or delayed audio starts. Some people have had to experiment to resolve the problem. To use a console command, make sure that the chat isn't active. When you type the colon ':' key, it'll pop up a line in the game window, not the chat bar. Finish the command and hit enter. Other values you can try are 4096 or 8192. (Any multiple of 4 should work, these are just convenient values.)
You might also try the beta client seen here:
viewtopic.php?f=39&t=66937This client helps reduce CPU load of the game and may resolve other issues from this. I'm sure lofar (Seatribe's code gnome) would appreciate feedback on if it resolves such problems without the need to change the audio buffer size.
As far as the cause... it's mostly a java issue, but overall could be due to the sound device you have in your system, a slower CPU, or other possible sources for such problems.
Opinions expressed in this statement are the authors alone and in no way reflect on the game development values of the actual developers.