Research on voice feminization is still preliminary, but so far three kinds of intervention have demonstrated results:

Raising of fundamental pitch;

Change of resonances (the “quality” or “color” of the voice, which depends on the shape of mouth, lips, tongue etc.; technically, raising of formants);

And intonation patterns, including higher percentage of rising pitch (sometimes disparaged misogynistically as “uptalk”), and range of pitch variance (more ups and downs).

Cisgender women—more accurately, humans not exposed to testosterone—have, on average, higher pitch and higher formants (a “brighter” sound) due to anatomical differences. On the other hand, intonation patterns stereotypically considered to be “feminine” aren’t actually real; as a group, women’s intonation is pretty much as variable as men’s. However, stereotypical patterns appear to provide a small contribution to the perception of trans women’s voices as “female”.

Though these three factors have been shown to change perception, results so far are mixed; some trans women have more success than others. (It should be noted that not even cisgender women are rated as “women” consistently; “masculine” appear to be the default for voice perception.)

Today’s article is a case study and a case in point. The patient, “ Alex”, is a troubled teenager in the autism spectrum, with communication difficulties beyond dysphoria. Alex was treated with general voice training, as well as an intensive feminization program: two sessions per day, 60min per session, every day for two weeks. The main interventions were pitch raising, and resonance; the latter followed Hirsch & Gelfer 2012 (basic techniques include spreading more the lips, and keeping the tongue more to the front).

After the training, Alex’ speaking pitch improved from 145.44–146.39 Hz to 165.97–179.45 Hz, sucessfully moving into the normal female range. Double-blind listeners rated the post-treatment voice as significantly more feminine than pre-; but still, the increase wasn’t enough to bring ratings over 50% (they went from ca. 12–25% “feminine” at the start to ca. 25–40% by the end, touching the 50% mark mid-training). This is the same result as previous studies: that pitch alone helps, but isn’t enough. On the other hand, this study contradicts others in that resonance training, by itself, had no sigificant effect on listener’s perception. The authors note that this may be due to the short time frame available; previous studies say it takes time to develop proper resonance. (I also note that they don’t mention larynx-based resonance techniques, popular in the online transgender community.)

On a personal note, Alex’ story is heartbreaking. It’s not always that the introduction to a scientific article makes me cry.