Speech therapy

Trans people often undergo therapy or training to alter their voice as a means of expressing their gender. This can include a number of factors such as learning to alter pitch and resonance to emulate biological factors common in the genders they identify as, or adopting gendered inflections from their culture or society.

"Resonance"
"Resonance" is one of the major factors that can play a role in others perception of how your voice indicates gender. Unfortunately what this means can often be unclear as vocal resonance is not the same as the resonance referred to in acoustic physics. To be more precise it refers to how the shape, size, and rigidity of the vocal tract affect the timbre and dynamics of a voice.

Factors
Shape: the differences in the shapes of the vocal tract's spaces such as the throat, sinus, mouth, and nasal cavities can influence the timbre of the voice by creating a distinct array of alterior frequencies to give it a unique color. Size: a larger vocal tract can create a darker voice by lowering the alterior frequencies created through reverberation within the vocal tract. Rigidity: the rigidity of various sections of the vocal tract can be influenced by fat, bone, cartilage, and muscle to change the volumes of the alterior frequencies. In particular less rigid sections are more likely to absorb these extra frequencies than to propogate them as a harder surface would.

Pitch range
Differences in the pitch ranges between genders are in large part due changes caused by sex hormones. Testosterone in particular significantly alters the voice through increasing the length and thickness of the vocal chords, the size and orientation of the larynx, and the size of the vocal tract in general. Some of the pitch quality may be due to conscious or cultural reinforcement though it mainly comes from the fundamental tone generated by the vocal folds/chords inside the larynx. Specifically, testosterone causes the vocal pitch to drop as the vibration is slower in the longer and denser chords that it causes, though it can be further lowered through relaxing them, or heightened by flexing them taught. Though there may be outliers for a variety of reasons, the average ranges that cis people generally move between throughout conversation is as follows:
 * Roughly masculine range:
 * minimum: 70hz ~ C#2
 * fundamental: 110hz ~ A2
 * maximum: 350hz ~ F4


 * Roughly feminine range:
 * minimum: 140hz ~ C#3
 * fundamental: 220hz ~ A3
 * maximum: 700hz ~ F5

Non-binary pitch range
There is not a specified range for non-binary people, but when striving for an ambiguous presentation some inspiration might be found by looking at what is between these pitch ranges. The "overlapping" range below shows what frequencies are often found in the vocal ranges of both males and females, whereas the "midway" range is generated from the points halfway between the male and female ranges.
 * overlaping range
 * minimum: 140 ~ C#3
 * maximum: 350 ~ F4


 * midway range
 * minimum: 105hz ~ Ab2
 * fundamental: 165hz ~ E3
 * maximum: 525hz ~ C5

Inflection
Inflection is the use of varying tones and dynamic volume to indicate subtle emotion and meaning overtop of language, it's use can vary greatly from social influences such as nationality and subculture. In terms of correlation with gender, women often have much more inflection when the subject matter is "lively" as well as much less inflection when the subject matter is less so. Men on the other hand may statistically maintain a more steady amount of inflection despite changes in the emotional intensity of the subject matter. That said this is not a hard rule and seems to be cultural, as these roles have been shown to be inconsistant depending on the area surveyed.

Hearphones
Hearphones are a device that reflects one voice back into their own ears while also sheilding the ears from reverberations from nearby objects. This can help someone hear their own voice more accurately as another person would. Having accurate feedback can help build confidence one's voice sounds like they intend it to, as well as allow one to know what effects can result from using the various muscles of the vocal tract. In the absence of a specialized device one may rig a makeshift one using books held up to the ears to reflect the voice similarily to hearphones.

Guitar tuner
Guitar tuners are sometimes used as a way to check the fundamental pitch of ones voice while learning to alter it. The notes the tuner measures can be cross referenced with the rough vocal ranges shown to help as a target for practicing in this method.

Recording setup
A recording setup can be helpful to listen back on progress, get live feedback, or use software such as spectral analyzers or guitar tuners to understand and tweak the finer deals of ones voice. The setup may be more or less composed of the following:
 * Microphone
 * Earphones/Speakers
 * Computer
 * Noise cancellation
 * Acoustic dampening foam
 * Pop filter
 * Shock mount

Prompt material
Having access to books, music, or other reading material can sometimes help during the early stages of practice if one is having trouble multi-tasking. Changing ones voice while also thinking of something to say might be difficult at first, but eventually one should move on to live conversation or improvised dialogue to get over this crutch.