How does one even pull that off? What would be her explanation to friends and family? Or did she slowly lower her tone over the course of months or years, so they didn't even notice?
In high school I noticed my sister wore glasses when going out with her friends, but never at any other time. And, after a year or two in high school, hasn't ever worn glasses (that I know of) for many years after. It was clearly just an affectation for her friends and her family just made fun of her in private about it.
You don't have to fool your family about stuff like this. Just your marks.