I have to be careful regarding my observations with Janet aged 11, who spoke in a gruff male bassy voice. Could it have been a hoax? When adult women are trained for a deep singing voice, it is possible, please listen to female Mongolian throat singers on link below.
However i did learn as much as i could from Janet, there wasn't any singing training, my thoughts were for a child to shout and swear in a deep male voice, which she did for long periods of time, would have damaged a young girls throat,
which surprisingly did not happen.
https://www.youtube.com/watch?v=qNFSB4PnVPI
Above link is the female Mongolian throat singer.
Below again is how Janet aged 11 talked, you will have to make your own mind up!
https://www.youtube.com/watch?v=17Xhed0jP50