Hm. They're not as clear as the spectrograms we get in elementary phonetics, are they?

I've never heard The Simpsons, so I don't know what Marge's sound is, but when I follow your directions and add creaky voice then pharyngeal constriction to an [m], lordy lordy, does it sound like a wounded muskrat or a sexually frustrated wookiee -- Not that I've heard either of those either, but I just know that's what they'd sound like.