The whole vocal experience puts dolphin communication closer to that of humans than any other species, the report said.

CNN: Dolphins may be calling each other by name

"When they sat down to write Over The Rainbow, they were writing for somebody who had the vocal range and the sincerity and the capability of communication that those in the know in Hollywood already felt she had, " explained Ken Sefton of the Judy Garland Club.

BBC: NEWS | Entertainment | Over The Rainbow's enduring appeal