Having voice and speech characteristics align with one's gender identity is often important to transgender individuals, whether their goal be feminization, neutralization or masculinization.
Fundamental frequency, closely related to pitch, was initially thought to be the characteristic most effective in voice feminization.
[5] The changes with the greatest effects towards feminization, based on current evidence, are fundamental frequency, vocal weight and voice resonance.
[4] Voice therapy is generally not required for transgender men as the effects of testosterone on the larynx result in a deeper pitch.
[10] Therapy techniques may involve finding a person's most comfortable pitch range, using breath support and relaxation exercises, introducing voice strengthening warm-ups, stabilizing posture and increasing chest resonance.
[10] In the case of AI vocal gender identification examples, key features noted to effect gender perception included fundamental frequency and formant frequency as well as further source related measures including cepstral peak prominence (a rough measure of harmonicity in voice with low values indicating a higher likelihood of dysphonia) and rolloff in energy between the first and second harmonics.
[11][12] A 2020 study in the International Journal of General Medicine noted other factors being involved in gender perception, saying: "a minimum F0 value of 180 Hz required for a voice to be perceived as feminine".
[14] While hormone replacement therapy (HRT) and gender reassignment surgery can cause a more feminine outward appearance for transgender women, they typically do nothing to alter the pitch of an adult voice or to make the voice sound more feminine,[15] unless HRT is started immediately after puberty blockers during teenage years.
A positive effect of surgery can be protecting the voice from damage due to the strain of constantly elevating pitch while speaking.
[5] As for transgender men, it is generally presumed that hormone therapy does successfully masculinize the voice and lower vocal pitch.
This mimics the changes that the vocal folds non-transgender men go through during puberty, which causes a lower sounding voice.
The most common focus in transgender voice therapy is pitch raising or lowering; however, other gender markers may be more important for an individual to work on.
[5] Clients and clinicians should discuss goals of therapy to ensure that they are working together toward the voice that most fits the person's gender identity.
[4] In a review of speech literature, Davies and Goldberg (2006) were unable to find any clear protocols for transgender men's voice therapy.
The first step in therapy is determining the habitual speaking fundamental frequency of the individual using an acoustic analyzing program.
This is accomplished through several tasks including sustained phonation of the vowels [i], [a] and [u], reading a standardized passage and producing a spontaneous speech sample.
SOVT techniques include phonating into straws, lip or tongue trilling, and producing multiple speech sounds such as nasals (e.g., [m] and [n]), voiced fricatives (e.g., [z] and [v]), and high vowels (e.g., [u] and [i]).
Modifying the length of a vocal tract results in a change in resonance and in pitch, as can be shown by pronouncing a prolonged [s] while protruding and retracting the lips.
[10] Deborah Tannen's book, You Just Don't Understand (1990), is referred to by the authors as a seminal work on the difference in men and women's non-verbal communication.
This may manifest itself in health care providers being more reluctant to treat transgender clients because of an unwillingness to find information about their specific population.
[4] Critics cite variability in outcome, lack of outcome data, and reported negative effects like compromised voice quality, decreased vocal loudness, adverse impact on swallowing/breathing, sore throat, wound infection, and scarring as reasons to avoid vocal surgery.
[5] Proponents argue that surgery may protect a person's voice from damage caused by repetitive strain to elevate pitch in therapy.