In the 1960s NASA-funded scientists tried to teach dolphins to speak

In the 60s a NASA-funded a project to teach dolphins to speak which involved flooding a house and living with them. One researcher even developed n intimate relationship with one of the dolphins.

Dolphins were claimed to have learnt words such as “ball” and “diamond” but struggled with the letter “m”.

http://www.telegraph.co.uk/culture/film/10860676/The-woman-who-lived-in-sin-with-a-dolphin.html