Sound is the energy form that is transmitted most efficiently in water. Audio signals are therefore a very important source of gaining knowledge about the environment, both for the majority of animals in the ocean and marine scientists. Animals use underwater sounds for communication and orientation. In humpback whale case will sound be used to find partners.
During migration and breeding areas males sing long, complex songs, familiar to most and probably the most complex vocalizations in the animal kingdom. As it is known from birds, different groups of the same species are often separated in their singing, but what is significant for humpback whales is that the song changes all the time. Under this change the song often exchanged parts of the song with parts of neighboring stocks song. Humpback Whale Song is still a mystery – a language not yet decoded. Nevertheless, there are many theories for what the humpback whale trying to communicate and what effect the sound of the humpback whale’s song can have on the human psyche. The song is being used as an alternative treatment in holistic therapy. Research say that it should have a soothing, sometimes healing, effect on humans.

An auditory illusion is an illusion of hearing, the aural equivalent of an optical illusion : the listener hears either sounds which are not present or “impossible” sounds. In short, auditory illusions highlight areas where the human ear and brain, as organic, makeshift tools, differ from perfect audio receptors (for better or for worse).

The tritone paradox is an auditory illusion in which a sequentially played pair of shepard tones separated by an interval of a half octave, is heard as ascending by some people and as descending by others. Different populations tend to favor one of a limited set of different spots around the chromatic circle as central to the set of “higher” tones. The tritone paradox was first reported by psychology of music researcher Diana Deutch in 1986.

The basic pattern that produces this illusion consists of two computer-produced tones that are related by a half-octave. (This interval is called a tritone). When one tone of a pair is played, followed by the second, some people hear an ascending pattern. But other people, on listening to the identical pair of tones, hear a descending pattern instead. This experience can be particularly astonishing to a group of musicians who are all quite certain of their judgments, and yet disagree completely as to whether such a pair of tones is moving up or down in pitch.