If I remember correctly, babies learn to distinguish vowels from consonants from near birth when adults speak to them in that annoying high pitched "coochy coochy coo" dialect. After 6-12 months of life this starts to hold them back as they need to transition to hearing normal sounds and seeing the people mouthing them. The puppets with hinge-flap mouths, exaggerated and insanely high pitched accents in Sesame Street are ridiculous. I would strongly discourage letting your little ones watch this show.
Also Sesame Street is very New York. The rest of the world doesn't live like this. I recommend local kids TV shows with real humons performing. Some short cartoons are fun, many of them are terrible, but the sum total of TV is dose dependent. Turning it off straight after their favorite show might result in a little argument but you'll be pleasantly surprised when 5 minutes later you catch them doing something (anything) else. Usually something creative, social, and developing fine motor skills, if not simply running around outside. And subsequently you'll find them turning it off themselves.
Many countries had local versions of Sesame Street. I watched the spanish one when I was a kid and felt totally identified with the people and scenarios there.
Neither all the characters had high pitched voices (just rewatched a bit to confirm my memory :)
I remember some Christmas special that (contrary to my country's version) had all these different characters, black and Asian kids, Big Bird and the story took place in this extremely urban setting of NY. This was in the late 80s or early 90s and I still remember how big of a difference this was for me.
I haven't been a kid in...too long, but I have a decent recollection of Sesame Street, and I don't recall an excess of high pitched voices.
Elmo and several of the girl muppets are pretty shrill, but Oscar, Grover, Big Bird, and all the humans are normal. Kermit, Bert and Ernie have that rounded "muppet voice" which is kinda in between.
Screen time isn't great but Sesame Street is hands-down among the best childrens' television in existence.
At the age when kids watch Sesame Street, they understand spoken language well and there it is ridiculous to worry about their ability to learn language.
Also, even kids that are hold back due to in high pitched accents are hold back little bit for like two months maximum, so it completely absurd to worry about any of that.
