From Season 2 (19701971). Formerly included in the roster of classic clips no longer on SesameStreet.org. This is Jim Henson's disembodied facial creation called Limbo, or (a.k.a.) Nobody, voiced by the golden throat of beat poet, social activist and New York radio personality William "Rosko" Mercer. Although to date, the jury is still out on this, but I think it's highly plausible that the electronic sounds were the work of Raymond Scott at Manhattan Research, since he and Jim Henson were the collaborators in Limbo's maiden voyage "The Organized Mind".

I want to give honorable mention to Melissa S.B. Mercer, ‪@mercerizedx6‬, who I found while searching for some of her father's other work. I don't know if she is still active, but here's her channel:    / @mercerizedx6