CNN CNN Newsroom April 7, 2014 13:38:00
Its a frequency designed to be heard not by the human ear, but by acoustic listeners. those acoustic listeners will then provide both a visual reference point, a wave form, and an audio sound which can be heard then by the ear. the pinger is not only designed for the 37.5, but the rhythmic one-second pings. theres many noises in the ocean. some of them are mammal made. others could be from other machinery. the sound -- we learned last night and over the last few days sound travels far, especiall...
Source: archive.org