It Is of interest to note that while some dolphins are reported to have learned English -- up to 50 words used in correct context -- no human being has been reported to have learned dolphinese.
Source: In The Speaker's Electronic Reference Collection, AApex Software, 1994.
-- Carl Sagan, (Nov 9 1934-1996), US astronomer; He provided insight in the origin of life by producing amino acids in a mixture of chemicals irradiated by ultraviolet light; wrote Contact.