You may find that when the ANR-20 headphones are used with the noise reduction
engaged, a jolt to the headset or violent bounce will cause the sound to
briefly mute (cut out). The reason for this is in how the noise reduction
works:

- Microphones are placed on the headset, which 'listen' to the surrounding
  environment (and its noises).

- Circuits in the headset compare the environmental noise with the music being
  played, then take the detected noise and turn it 'out of phase.' This out of
  phase noise signal is mixed with the music playing in your ears, and cancels
  out the undesirable noise, leaving only the desired music. 

However, when the NR mics are physically jolted, they and the NR circuits may
be overloaded. This will cause the NR circuits to momentarily 'mute' and the
sound may stop playing for a moment. This behavior is necessary to protect 
the circuits from damage and to protect your ears from loud transient noise
surges. 

In severe environments such as when an airliner encounters turbulence or in a
four-wheel-drive vehicle on a very bumpy road, it may be necessary to use the
headphones without the NR feature enabled. Of course, we recommend NOT wearing
headphones in these rather extreme situations, as your safety may be
endangered and you should be alert to what is going on around you!
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