Folklore around my area has always (as long as I can remember) been that "after a certain age, little old women turn into little old men."

Changes in what are commonly called "secondary sexual characteristics" are well documented in the literature, both clinical and popular, about perimenopause. It is certainly reasonable to expect that changes in voice quality can occur.

Whether "protecting the voice" is material to whether a woman should engage HRT is something that only the woman (and her physician) should decide.

John