1 a wasting away of the body, as from poor nutrition, nerve damage, or disuse. 2  to undergo atrophy; wither; degenerate:His crippled leg began to atrophy with no exercise. 3  to become weakened; decline:Industry atrophied in bad economic times.
Voice Amplifiers / Long Range Listening Devices. Listening devices can be utilized for a variety of purposes including listening through a wall, listening from a distance or enjoying your favorite animals in the wild. More complex systems contain an audio transmitter and receiver.
Sound-producing Device (bell, horn, whistle, etc.) Every vessel less than 12 meters (39.4 ft) in length must carry an efficient sound-producing device. The sound-producing device need not meet any particular specifications, as long as the vessel can produce signals required by the navigational rules.