Um, you can even tell?  Ok, to the astute observer I am trying to change my voice, but it's nothing I can maintain for more than short comments or sentences.   Too often when I try to keep a conversation with a feminen voice I get "what?", "huh?".  So I often have to revert to a more male voice to communicate.  Also, it's hard to talk for long conversations and maintain a female voice.  Bless you if you think I can sound that way now.  This is a very difficult thing to do and have it sound 'normal'.  I've read what others have tried, recorded my voice, sing in the car and practice talking to the cats.   It's work and something that will hopefully improve with practice. 

The issue is resonance, not pitch.  Some women have low voices and guys can certainly alter their pitch to be higher.  However, it doesn't sound feminen because of resonance.  A woman's voice box is positioned higher in the throat and has a shorter distance to go.  Think of different musical instuments playing the same note.  They have the same pitch, but the quality of the sound is different.  No surgery yet takes care of that, although I know one doctor who has a procedure that at least removes the adams apple and raises the pitch, but might also re-position the voice box a little higher.  But this was just his own speculations from about 2 years ago about repositioning the voice box.  IF i have any voice surgery, it won't be until 2009 and I'm just not comfortable with the voice I've been able to achieve.  Most MtFs do achieve a satisfactory voice with practice.  I'm hoping I'll be Ok by then.