With my voice, here's what happened. When I first went out as a female the first time, I talked in as much of a female voice as I could muster up based on what I had read on the internet. I guess it was androgynous, although it would occasionally slip into a chest voice. Eventually, I developed what I would call my "pleasant voice", which was a head voice and the pitch varied somewhat when I talked, but my pitch wasn't really raised much (you have to raise pitch to achieve a head voice). I wanted to get my voice to sound unambiguously female so bad. I had been trying to use "finding your female voice", but I didn't seem to be making progress. One of my problems with that particular program was that I had such a large vocal range, it was difficult finding the correct pitch. I went to a speech therapist about 3 months after I had started HRT and shortly before I would be going fulltime. I had 4 sessions with her over a period of a month (the first one revolving around finding the right pitch). I kept practicing (usually only while driving) and after a couple of weeks, my voice just started changing by itself. I had been talking in a chest voice at work, but I used a head voice for my female voice. Somehow, it started magically staying in the head voice even at my normal chest voice pitch. It flipped back and forth for about a week, and then it pretty much has stayed in a head voice ever since. I stopped fighting to keep my chest voice at work even though I wasn't out yet and fortunately nobody seemed to notice (or care).
I don't know if hormones or voice training (although with how soon after starting training that my voice changed makes me somehow doubt it was training) that my voice changed. The effect of the change wasn't really with the pitch (which I went up over time due to practicing I believe), but rather that I lost the ability to easily speak in a chest voice even if I tried to. I *can* still talk in a chest voice, but it requires a lot of concentration and relaxing almost everything. It kind of screws up my voice for a while though and hurts, so I rarely do it.
I know my voice still isn't perfect yet (I've gotten sirred on the phone even when trying, which is probably due to me getting lazy for a while), but I continue to improve it and I do hope that over time, it will sound perfectly female regardless of whether I try or not. As Regina said, you need to work at it and I kind of relaxed for a while and slipped a bit. At the very least, it's androgynous because I do get ma'amed over the phone most of the time. In person I think my face tends to make my voice be perceived as female though since I don't have any problems in that regard, even with a cold (which I've had for the past 2 and a half weeks).
One thing that I have improved a lot is my singing voice. I had to so I could be in my musical. It's certainly not excellent, but it *does* pass. Plus I'm even doing a small solo part.
I kind of sing in falsetto, but I also push air with my diaphragm (rather than my lungs) and keep an open throat (while still tightening my vocal cords) and it seems to work just fine. In other words, I'm just using proper singing techniques, but manipulating my throat and vocal cord muscles into more of a falsetto fashion and it seems to work. Using your diaphram give your voice a somewhat breathier quality with the falsetto position of the vocal cords balancing it out and the open throat is especially important when singing higher pitched notes. That's about the best way I can describe the technique I use to sing in a passable female singing voice at least. It's definitely a different technique than speaking as a female or singing as a male, but the result is great. If the voice starts sounding a bit pinched (and falsetto), just increase the throughput of air volume.
