Happy Feet - Who ARE The Frog Chorus?

[Skekayuk]

I have been pondering the question, opn the number Happy Feet, which was sung by Kermit The Frog and a Frog Chorus in the Madeline Kahn episode of TMS, who out of the available puppeteers are singing in the 'Frog Chorus' accompanying Jim Henson's Kermit?
I know that the episode occurs quite early on in Season II, therefore the puppeteers singing in that chorus could include: Frank Oz, Richard Hunt, Jerry Nelson, Dave Goelz or Louise Gold. But which of them are actually singing in that Frog Chorus?