There are two ways a buzz or rattle sound can be introduced to the sound from
the headset's subwoofer/bass shakers. 

1) When the headset microphone is installed and active (not Muted), and both
   it and the subwoofers are turned up loud, the vibrations from the subwoofer
   can actually shake the microphone and cause a vibration to be sent to the 
   audio input, which is played back by the subwoofers, which shakes the 
   headset microphone, which creates a shaking sound that is sent to the 
   subwoofers, which play back that sound, and so on. 

   This is a FEEDBACK LOOP, but only in very low frequencies, so does not 
   produce a 'howling' feedback sound. 

   The solution is to turn down the level of the subwoofers, microphone, 
   or both. 

2) If you play the subwoofers very loud for long periods of time, the physical
   mounting of the drivers in the headset may begin to loosen up and you may
   hear a rattle along with the playback from the subwoofers. This is similar
   to playing a subwoofer really loud in your car for a long period of time.
   Eventually rattles will develop in your car's interior, which you may hear
   along with the output from the subwoofer. 

   Again, the solution is to play the subwoofer at more moderate levels so
   that you don't shake the headset apart. 

   It's also a good idea not to play the subwoofers too loud, to avoid damage 
   to your hearing. Continuous, long-term exposure to loud sound levels has 
   been proven to cause hearing loss. 
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