While do-it-yourself YouTube videos from transgender women are available, sessions with a voice specialist can improve forward resonance and soften an elevated pitch, so someone doesn’t sound like Minnie Mouse, Dr. Hancock said.

Another voice quality to consider is intonation. While men tend to speak in a monotone fashion, women generally have more highs and lows, something Ms. Marat mastered during about a year of group and one-on-one lessons and practice at N.Y.U.

Her fundamental pitch is consistently elevated in the feminine range at about 185 hertz, up from 147 hertz. Still, if Ms. Marat speaks for too long, she gets out of breath, and she feels she speaks too softly.

On Tuesdays, Ms. Marat works with Sam Jaffe, a graduate student at N.Y.U., to get her vocal cords into better shape so she can raise her pitch and volume to where she wants it without becoming breathless. “Voice modification therapy is kind of analogous to going to the gym for your voice,” Mr. Jaffe explained.

But while therapists help clients gain technical skill, it’s up to each patient to “own” his or her new voice and figure out what sounds right for them, said Leah Helou, the director of the transgender voice program at the University of Pittsburgh Medical Center.

“It’s not my job to make someone into an image of a lady as I see fit,” Dr. Helou said. “The danger when they come to me is they think, ‘She’s going to tell me what I need to do to pass.’”

Speech and language therapists have been working with transgender clients as far back as the ’70s, but it wasn’t until 2006 that the first textbook was published. In the past decade, the number of speech pathologists and voice clinicians learning to work with transgender clients has grown exponentially.