comm sound effect
  I managed to get a good comm sound effect that's very close to Raven's. It's the sound effect when Kyle is talking through a comm link. 
 Get a trial of GoldWave here  
http://www.goldwave.com/) 
 Open up your sound file and go to effect>>filter>>bandpass/stop 
 Initial frequency range
 From (Hz) 500
 To (Hz) 5500 
 Settings: check bandpass and static 
 Steepness: 2