Vocal folds

The vocal folds, often called vocal cords, are two bands of muscle and tissue inside the larynx that vibrate as air passes between them. Their length, thickness and tension set the pitch and much of the weight of a voice.

Folds or cords?

"Folds" is the term most clinicians now prefer, because they are layered structures with a flexible covering, not strings. You will see both words used, often on the same page.

How they make sound

The folds run front to back across the top of the windpipe, joined at the front just behind the Adam's apple. When you breathe they sit apart; when you speak they close, air pressure builds beneath them, and they are blown open and snap shut again, very quickly. Each cycle releases a small puff of air, and the rate of those puffs is the fundamental frequency you hear as pitch.

Three things change that rate. Longer folds vibrate more slowly. Thicker, heavier folds vibrate more slowly. Tighter folds vibrate faster. Every pitch-changing operation works on one of those:

• a glottoplasty shortens the vibrating length
• cricothyroid approximation tightens it
• laser voice adjustment aims to reduce the mass
• a relaxation thyroplasty slackens it to lower the pitch

What you control and what you don't

You cannot change the length or mass of your folds by training. You can change how much of them is in contact and how firmly they close, which is most of what vocal weight is, and you can adjust their tension within the range you have, which is how pitch moves when you talk. That is why training works on pitch and weight, and why it runs into a limit that only surgery or testosterone can move.

Resonance is not made by the folds at all. It is shaped above them, in the throat and mouth, which is why no operation on the folds changes it.

What hormones do

A testosterone puberty lengthens and thickens the folds, which is most of why the voice drops. For trans men, testosterone in adulthood thickens the folds, which lowers pitch a long way for most people, to a degree that varies. Oestrogen does nothing to them. That is the single biggest reason voice work for trans women is training first and surgery second.

How they are looked at

With a scope through the mouth or nose, usually with stroboscopy to see the vibration in slow motion. Anyone considering voice surgery will have this done first, and again afterwards to check healing.

Looking after them

The folds are covered by a thin, soft layer, and it is that layer that makes a clean, easy voice possible. Anything that roughens or scars it costs you: shouting, long periods of pushing a voice somewhere it does not want to go, smoking, and reflux. Surgeons care about all of these before operating, and the smoking and reflux page explains why. After surgery on the folds, the same layer is what voice rest is protecting.

Common misunderstandings

Hoarseness is not the folds "wearing out". Short-term hoarseness is usually swelling and settles with rest. Hoarseness that lasts more than a few weeks is worth a look from a laryngologist, whether or not you have had surgery.

A higher voice does not mean the folds are working harder. Held well, a trained voice uses the folds lightly. Strain comes from forcing, not from pitch itself.

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