Also that comment about training your voice to be high pitched made me curious. Can girls also do that to make their voice sound like male? Is there an age limit on when you can start? This manga is pushing me further and further to actually try cross dressing and idk what to feel ; ×;)
I've only had training for the other way around, so I don't know too much about it, but it's certainly possible. Like a lot of other things, it becomes harder to make big changes to your voice after you're about twenty-five or so, but it's still doable after that point, it'll just be a bit more difficult. The three big things to think about are your pitch, your resonance, and your tone. Changing your pitch is pretty similar to expanding your range as a singer: sing scales, going up and down (spending most of your time at the desired end of your range, obviously) and over time you can gradually become more comfortable producing lower or higher notes.
Resonance is about changing where your voice echoes in your body - to sound more masculine, you want to project your voice downwards, towards your throat and diaphragm, and to sound more feminine, you want to project your voice forwards and upwards, into your mouth and nose. It's hard to explain, and harder to consistently get right, but I think it makes the biggest difference in how people hear you, even more than your pitch.
By tone, I mean your manner of speech: men tend not to change their pitch too much when they talk, and accentuate words by changing how forcefully they say them, whereas women tend to modulate their pitch more widely and frequently. At least, that's what I was told - I think it's a bit iffy, and kinda plays to stereotypes, but if you're trying to sound like a man or a woman without drawing much attention to your voice, it's probably easier to sound like a stereotypical man or a stereotypical woman, than a man or a woman with a quirky voice. I guess.
Once you've put all that together, it's a matter of training your vocal muscles until they're flexible enough to make the sounds you want, and practicing talking with it until it's become second nature. You want to be careful not to overwork your voice too much, since you can easily hurt your throat if you try and force yourself to hit notes that are right at the edge of your range or beyond it, but as long as you take it easy, keep at it, and pay attention to how you sound, it's not particularly dangerous. The results vary from person to person, of course, depending on the kind of voice you're starting with, and I've simplified things a whole lot, but that's roughly what's involved.
