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Table of contents
  1. Vocal Mechanisms
    1. M0
    2. M1
    3. M2
    4. M3

Vocal Mechanisms

A vocal mechanism or register is a distinct configuration of vocal fold interaction. Which, is a complicated way of saying…

  • vocal mechanisms are distinct, they don’t overlap
  • they describe how the vocal folds vibrate
  • phonation is always within one of these mechanisms
  • you can pass between mechanisms without a break with training

modal voice





M0 or vocal fry is at the bottom of your vocal range. Try going to your lowest note, then relax a little and go lower. The rough sound similar to an idling motorcycle engine is from M0. This is when the folds are slack and the whole fold vibrates.

  • slack folds
  • whole fold vibrates
  • below your lowest M1 note


normal speech


chest voice

M1 is your normal speaking register.

  • where most people speak the majority of the time
  • most of the vocal folds vibrates

modal voice




head voice

M2 is a usually hollow, very high pitch register.

  • sometimes has a gap between folds / lack of closure
  • very high pitch
  • the TA muscles deactivate somewhat
  • mostly just mucosa of the folds vibrates

modal voice




flute register

There are different theories and types of M3, but the main one is with mostly complete closure and a lot of tension, such that only a part of the folds vibrates.

  • mostly only a small part of the folds vibrates and only the mucosa
  • usually starts at 1000hz and can go as high as 5000hz or more.

This type of M3 is called stop closure whistle by Antonio Di Corcia and Franco Fussi’s paper↗ which puts forward the following findings:

FLW - Female Laryngeal Whistle

  • “very thin, stiff and tightly stretched vocal folds”
  • “Often, no contact between the folds during phonation was noted”

SCW – Stop Closure Whistle

  • “the whistle sound depends on a tiny orifice at the anterior third of the folds”
  • caused by high adduction
  • “HSDI observation showed a total absence of vibration (normal periodic vibration) in any components of the vibrating system caused by the stop_closure phenomenon”

IW - Ingressive Whistle

  • “high activity of the adductor muscles”
  • “absence of vibrating parts during ingressive phonation”

Scream in M3

  • “[…]very stretched, thin and stiff vocal folds and an high constriction of the false vocal folds”
  • “[…]very further reduction of the mucosal wave vibration, very restricted to the edge of the fold”