Formants

Formants are the frequency bands that the throat, mouth and lips amplify as sound passes through them. They are what makes an "ee" different from an "oo", and they are the measurable side of what people call resonance.

Where you'll meet it

In voice training apps and spectrograms, where you may see F1 and F2 plotted as lines or dots, and in any explanation of why a voice at the same pitch can sound male or female. On this site, resonance is the everyday word; formants are what resonance looks like on a screen.

What they are

The vocal folds make a buzz with a basic rate, the fundamental frequency, plus a stack of higher overtones. The space above them, from the voice box to the lips, then boosts some of those overtones and damps others, depending on its length and shape. The boosted bands are the formants. They are numbered from the bottom: F1, F2, F3 and up.

Why they matter so much

A longer vocal tract has lower formants, and a testosterone puberty lengthens it: the larynx drops and the neck grows. So a listener hears lower formants as a larger body and, by association, a male one. That signal is independent of pitch. It is why someone can speak at a raised pitch and still be read as male, and why someone at a fairly low pitch can be read as female.

Formants are also largely the part of the voice surgery leaves alone. Some surgeons say a feminization laryngoplasty shifts resonance a little by making the voice box smaller, but most of the change comes from where you hold the larynx, the space you make with the tongue, and how much you spread or round the lips. Those are habits, and habits are trained. That is most of what feminization training is working on, even when it is not called by this name.

How they are measured

With a microphone and software that draws a spectrogram, a picture of which frequencies are loud from moment to moment. Formants show up as dark horizontal bands, and apps pick out F1 and F2 and plot them. Several free and paid apps do this, and therapists use similar tools in sessions.

The readings are useful and easy to over-trust. They change with every vowel, so a number only means something when you compare the same vowel to itself. The microphone, the room and the software's settings all shift them. And an app's "feminine range" is an average drawn over a lot of overlap between speakers. I would use the graph to see whether a change you made moved things in the right direction, not to chase a target line.

Common misunderstandings

Formants are not pitch, and they are not the same as the "chest" and "head" resonance singers talk about, which describes a sensation more than a measurement. Raising pitch does not raise formants on its own; you can go up in pitch with the same dark, large-sounding tract behind it, and that is exactly the combination that reads as a man speaking high.

They also do not have to be pushed to an extreme. Overdone brightening, with a squeezed throat and a fixed smile, sounds tense and costs effort all day. Most people find a moderate shift, held easily, reads better than a dramatic one held with effort.

For trans men

Testosterone lowers pitch, but it does not lengthen an adult neck, so formants move less than pitch does. That is part of why some trans men find their voice has dropped and still reads younger or lighter than they expected. Darker resonance can be trained in the same way, in the other direction; masculinization training covers it.

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