The speculation has been sparked by a 1979 TV interview with Waits, which has recently been discovered on YouTube by Batman fans. During the interview, Waits's speaking voice and mannerisms display an uncanny similarity to Ledger's memorable portrayal of The Joker in The Dark Knight. Scroll down to watch the interview.
[video=youtube_share;gCSc6E4yG9s]http://youtu.be/gCSc6E4yG9s[/video]
http://www.nme.com/filmandtv/news/heath-ledgers-joker-inspired-by-tom-waits/277572