The mechanisms of the talking toys had changed a lot. 30 years before Barbie Teen Talk it had been a milestone to be able to make Barbie talk, for the mechanism had to be reduced so much to fit her small torso.
60s talking toys had a mini record player inside with a pullstring mechanism that when pulled turned a grooved disc and a metal needle produced sound from it by traveling through the grooves. Dolls like Chatty Cathy had spoken lines of 3,24 sec. but the disc in Barbie was so tiny that lines couldn't last more than 2,5 sec. and were random. This challenge laid the foundation for for future talking toys scripts as one sentence had to express a complete thought and suggest a game pattern. There was no place for a plot development.
In 1992 advances allowed dolls to speak from an electronic chip programmed with a computer and these mechanisms made possible that the activist group Barbie Liberation Organization switched the chips of some Barbies with GI Joe and returned the dolls to the shelves to protest against gender stereotypes. So Barbie would say "Attack!" and GI Joe "Maths class is tough". While the link Teen Talk-Maths are tough seems to be the only thing that remained she told other things too. One doll could find the "maths tough" but still "study to be a doctor" while other could want "to sing a song" and "have a hawaian party", there was no way to control it and choose the more adequate ones to the interest of a child, so educators complained that the line could discourage little girls on maths.
Mattel apologised and promised not to use the sentence anymore but what to do with those on the market? Mattel offered to change them. It was foreseeable that stores would be looted by avid collectors in search of "The Phrase".
Undoubtedly, the topic of Barbie's talks is a singular subject with a lot of history and, a good part of it is explained in the autobiographic book "Barbie Talks" written by the woman in charge of Mattel's recording studio during the 60s and who was the first voice of Barbie, Gwen Florea.