Dolphin sound is a form of sound expression that has no pitch. It is an adjective describing a very high sound.

VITAS does not use any equipment. And the highest pitch is also There is no lip-synching (confirmed by myself at the Beijing concert), and there are some differences from the original recording. Of course people with 4 octaves can sing. Isn’t V just a human being?

About how high are the 4 octaves? , you can find it on the piano. You can listen to the C note in the fourth octave above middle C.