I installed a small shareware OSX app called “Vocal Lab”. It’s basically
a tuner for vocals. If you can sing (which I can’t), you can use
it to test your intonation.

It basically graphs the pitch of your voice (both in terms of
hertz and musical notes).

But the more interesting part is that I now now my speaking
voices ranges from about 105 hertz (A2 or so) up to
about 128 hertz.