When I was in college I had to change my voice.
The weird thing is, I can't remember exactly when I did it. I think I became aware of the problem at the end of my freshman year when we had to give evaluations to the people in our Torrey groups. People told me I sounded "angry" and they couldn't understand why. I think that was the point where I realized if I sounded angry naturally, I could sound "not angry" if I put some effort into it.
My natural way of talking tends to be monotone and come from lower in my throat. And that's the type of voice I was using in class without really considering how that sounded. I never used to uptalk. I didn't think about what facial expressions I was using.
Now, my old voice was still immediately recognizable as feminine. I've never been mistaken for a male on the phone, although at one point me and my 9-years-younger brother sounded eerily similar. In fact, recordings of my voice sound too high-pitched to me.
However, at some point in college I decided to make an effort to talk like a girl. And it worked. People smiled at me, laughed along with my jokes, and in general acted more friendly toward me in both class and other social settings. Again, I can't point to a specific time when this happened. It just did.
I made some small but specific changes to my style of speaking. Instead of speaking from the base of my throat (which I think is supposed to be your natural resonance) I spoke from somewhere in the middle. Raising the pitch of my voice just a little made everything softer and gentler. I learned how to uptalk, even though I initially thought it made you sound stupid. Now I can't stop doing it. :P I added more emphasis to my phrases, even making them sing-song. I used more gestures and facial expressions.
Years later I told a friend that I had changed my voice in college and used my old voice on him. It was actually hard for me to go back to that voice because I couldn't remember what I had sounded like. But when the other voice came out, my friend was shocked by how different I sounded.
I don't want to say I had to sound dumber or that girls in general have to sound dumber just to get people to like them. I think good intentions are not enough. If you have kind feelings in your head but you're not expressing them, people won't know what you're really thinking. So you have to emote.
But maybe I do sound dumber now. It bothers me that I can't turn off the uptalk even when I want to. I don't like that I have to choose between sounding uncertain and sounding mean.
On the plus side, now I know that my voice is somewhat within my control. I changed it once and I can change it again if I need to.