Most transgender women and men obsess with the problem of outing themselves with their voice. It seems no matter how well we present as our preferred gender, a slip up with our voice can ruin our whole day.
As with many other aspects of being transgender, there are many avenues coming along to help with our voices. As well as the many voice feminization services featured on line, more than a few hospitals offer voice therapy. In fact, even the Veteran's Administration does offer voice therapy too.
There is always the concept of vocal surgery which I have heard has varying levels of success. I have only ever encountered one person who had went through it. To be truthful I wasn't impressed.
Myself, I pursued the VA services offered to me with varied results. First of all, I was pleasantly surprised they were knowledgeable to what I was trying to achieve. I blame myself though for the results. Being essentially the lazy person I am, I gave up and have tried to improve my feminine voice through the very few lessons I ended up going through.
Over the years, what I have tried to do is try to match my voice to the cis women I am talking to. I imagine with varying levels of success.
The only time I can truly "try" out my feminine voice on strangers is on the phone. Even then, I am not competing on a level field. The majority of my calls come from the Veteran's Administration setting up appointments and going over results of my tests. Since the overwhelming majority of the hospitals' clients are male, the odds are stacked against me. Sometimes I still get called sir on occasion, except for the nurses and receptionists who have dealt with me a number of times. The example is my endocrinologist nurse. She is always very correct with her pronouns and calls me the proper ones.
With all the others who don't, I always gently remind them I am not a "sir" and go back to the drawing board. What am I doing wrong to trigger their response. Plus, as I said before, I am essentially a lazy person and since I so rarely encounter strangers anymore, it's only Liz I talk to.
Finally, the majority of the attendees of my transgender - crossdresser group have managed to settle into a softer version of their male vocal selves. Again with varying success. I suppose too, results hinge on what voice you had to start with. Many times feminine men have feminine voices.
Voicing their gender becomes increasingly easier.