Definition

The region in the water column where SOUND VELOCITY first decreases to a minimum value with DEPTH and then increases in value as a result of presĀ­sure. Above the minimum value SOUND RAYS are bent downward, and below the minimum value SOUND RAYS are bent upward; the RAYS are thus trapped in this CHANĀ­NEL. SOUND travelling in a deep channel can be detected thousands of MILES from the sound source.