Monday, April 28, 2014
Sound Can Play Tricks On Us
The formula for depth as a function of assumed position was derived for a model for sound that used the inverse square law for its propagation. This may not always be the case. When the distance from the source is large compared to the depth the model for propagation is closer to that a slab of material. The sound energy is confined to the region between the floor and ceiling defined by the ocean bottom and surface so the rate at which the intensity drops off will be closer to an inverse distance law. This is probably why whale songs travel such long distances. Another case is when the sound energy is confined by a tubular channel and the intensity can travel long distances with little change.
So one has to be on guard against a pinger's environment channeling the ping's energy. There may be whisper points that give false positions for its location. And the sonar operators were probably correct in their decision not to claim that they had located the Flight 370 black boxes but rather chose to wait until they had more reliable physical evidence to go by.