So I've started noticing my voice is kinda changing.  Not much in my everyday voice, but when I'd do goofy voices. 
I used to be able to do a great Herburt from Family Guy, but now my voice kinda cracks up.

I thought estrogen didn't change your voice after puberty.  Of course I didn't get a lot of testastone growing up, and I don't think my Adam's apple dropped.

So yeah......
Any ideas?

As far as I now E has negligible effect on the voice.  It has zero effect on the vocal cords themselves, but I suppose that the surrounding musculature reducing could have an effect.

Do you present with a fem voice regularly?  If so then you're using the vocal muscles in a different manner than you're used to...other than that I got nothing.

I would say that your voice changing is from muscle memory. Using your "new" voice for long enough it becomes second nature.

E does lean out the muscle mass of the vocal cords over time... just not the length. Length is the determiner of pitch, and thickness determines tonal qualities & strength.

More than likely though it just is habitual what you are noticing? It is pretty well accepted that HRT doesn't change the MtF voice.

I do think HRT changes the voice more than we think. I've noticed that there seems to be a common theme, where although the pitch of trans-women's voices does not change without training, the voice gets softer, less forceful, more feminine in tone.

I'm not sure if this is because of the HRT, or because of social differences where being around other women and imitating them makes us naturally start to copy their tone and inflection more, but I definitely have noticed a big difference. I can't shout like I used to, my speaking tone has gotten way softer (lots of people have been asking me to speak up recently,) and it has gotten REALLY hard to do my old male voice. When I try to do it now, it doesn't even sound like my old voice anymore. The pitch is there, but it just sounds... different... forced... not natural in some way anymore.

Quote from: Carrie Liz on April 23, 2014, 01:00:24 PM
lots of people have been asking me to speak up recently

I've run into this also. I never had a deep voice anyway; it was always soft but now no one can hear me at all it seems. And I got gendered female on the phone the other day without even trying to use my female voice. I believe that HRT is doing something with my voice.

HRT doesn't change your voice from what I've noticed and heard.  Still, my voice has been changing due to singing and training it. Even when I'm not trying to sound a certain way my voice is different from where I started.  I've been getting mistook or I should say accepted as female over the phone lately.  It's weird when it would happen at work and I'd confuse the people who were looking to speak with me, lol.  It happened enough times to make me feel good, but sort of confused since I didn't think it had changed that much. 

In any case, don't hold your breath for hrt to do that much.  Even if it does something, you will need to train your voice unless you started with a female voice. And don't hold off on that because it's one of the most important things we can do.   

I've noticed my voice getting clearer - so for example I can sing any given pitch that I could sing before more easily. The low edge of my range is the same, and the high edge of my high range is the same, it's just easier to hit those high notes than it was before. Nothing has happened to my normal talking voice as far as I can tell, with either the male or female version. I just have an easier time singing now and fewer days where my high range keeps crapping out on me.