I was rewatching the 'Joker Goes To School' episode the other night. Two things struck me:
One - when Joker and Susie are sitting in the cab of the truck Joker says they'll use the special microphone to disguise their voices but they sound just like themselves when they talk through it.
Two - Just before Joker and his goons leave the candystore hideout to photograph and blackmail the basketball team he says to get the camera and disguises. What disguises? In the gym they look as themselves?
Ah, one of my fave episodes. Okay, this is just my opinion on the first one. Yes, their voices do sound basically the same, but Susie's voice seems to go unnoticed until later in the Batcave, when Batman and Robin are listening to the recording of Susie's voice. Then there seems to be a bit of static interference in the background, which could have been feedback used to help "disguise" her voice. So, on the first hand it could be a script oversight, and on the second hand it could be a bit of sloppy producing. As for the disguises, I think that was also a script oversight. Unless the Joker's henchmen had been dressed as students when they appeared in the gym, haha. Again, only my opinions.
I prefer to believe it's because our hearts are pure. - Batman