There are two points in your life where voices become deeper. The first is at puberty where the male cords thicken slightly, the larynx elongates, and with that the cords stretch. The second is at "male puberty" where there is a further lowering of the voice - age 45 or so. For those who have the pubertal change, it is usually quite possible to obtain a reasonable female voice in tone and timber with speech therapy. For those who have reached the second plateau, not so easy. Usually surgical intervention is necessary in some form to alter the larynx and cords. The mickey mouse voice is much more common at this age. As yet there are no especially great surgeries. Some work for some individuals, others do not. Which one will work for you is the question. The key is to change the pitch, modulation, resonance, and timbre. The larynx needs to be shortened, so crico-thyroid approximation procedures are done. The pitch needs to be changed so the cords are tightened. The timber needs to be changed so the cords may be thinned or webbed. The modulation needs to be changed so the approximation of the cords may need to be adjusted. All these procedures are rarely done together, and not all of them are necessarily needed for the individual.
And after all this there is the how to talk like a female.
The FTM has no problems, T will do the job. Estrogen for the MTF will not reverse the changes from puberty.
