The limited visibility under water made sounds and hearing very important for them. They also use frequencies that reach far beyond our hearing capabilities. Of course they can also hear these higher frequencies. Just as we, whales use sound to communicate.
Dolphins usually use higher frequencies which limits the distance.
Even in complete darkness they can find their way through the ocean and also find their food. When you listen to the sounds you will usually hear two kinds of sounds. All sounds are copyright by Espaco Talassa. You can download them for private use only. None of the sounds may be used on other web pages and may not be distributed in any way.