Hey guys. I emailed LucasArts support about this and got a reply with some suggestions. I haven't tried them myself just yet. Here's a copy of the email text:
  There are new sound blaster Audigy drivers available that may help with 
 your problem. You can find these new drivers here: 
www.creativelabs.com) 
 Also, you may want to try adjusting the sound card's "hardware sound 
 acceleration level" in the DirectX Diagnostic Tool Sound menu. 
 - Exit the game
 - Click on the Windows Start button
 - Choose "Run..."
 - Type DXDIAG in the "Open" field and click OK
 - Select the Sound tab on the DirectX Diagnostic Tool
 - Lower the "hardware sound acceleration level" one notch and click 
 "Exit" 
 Try playing the game with this setting. If the problem continues to 
 occur, you may want to return to this menu and try a different 
 acceleration setting. 
 Please note that you may need to reset sound acceleration to the 
 original setting once you have finished playing the game to avoid problems 
 with other applications.