Hello guys!
I am building a basic 2d game which the characters are ducks. And the game will be awesome if their voices are ducks too. 
Donald Duck’s voice is not an effect, it was originally a recording of the voice actor Clarence Nash (https://en.wikipedia.org/wiki/Clarence_Nash)
Other actors have since imitated the voice.
There’s a description here of how the voice is created: https://en.wikipedia.org/wiki/Donald_Duck_talk