Editing Phonation (section)

===Myoelastic and aerodynamic theory===
The myoelastic theory states that when the [[vocal cords]] are brought together and breath pressure is applied to them, the cords remain closed until the pressure beneath them, the subglottic pressure, is sufficient to push them apart, allowing air to escape and reducing the pressure enough for the muscle tension recoil to pull the folds back together again. The pressure builds up once again until the cords are pushed apart, and the whole cycle keeps repeating itself. The rate at which the cords open and close, the number of cycles per second, determines the pitch of the phonation.<ref name="McKinney">{{cite book
| title = The Diagnosis and Correction of Vocal Faults
| last = McKinney
| first = James
| year = 1994
| publisher = Genovex Music Group
| isbn =  978-1-56593-940-0}}</ref>

The aerodynamic theory is based on the [[Bernoulli's principle|Bernoulli energy law in fluids]]. The theory states that when a stream of breath is flowing through the [[glottis]] while the arytenoid cartilages are held together (by the action of the interarytenoid muscles), a push-pull effect is created on the vocal fold tissues that maintains self-sustained oscillation. The push occurs during glottal opening, when the glottis is convergent, and the pull occurs during glottal closing, when the glottis is divergent.<ref name=":0">{{Cite journal|title = The physics of small-amplitude oscillation of the vocal folds|last = Titze|first = I.R.|date = 1988|journal = Journal of the Acoustical Society of America|doi = 10.1121/1.395910|pmid = 3372869|volume = 83|issue = 4|pages = 1536–1552|bibcode = 1988ASAJ...83.1536T}}</ref> Such an effect causes a transfer of energy from the airflow to the vocal fold tissues which overcomes losses by dissipation and sustain the oscillation.<ref name=":1">{{Cite journal|title = The minimum lung pressure to sustain vocal fold oscillation|last = Lucero|first = J. C.|date = 1995|journal = Journal of the Acoustical Society of America|doi = 10.1121/1.414354|pmid = 7642816|volume = 98|issue = 2|pages = 779–784|bibcode = 1995ASAJ...98..779L|s2cid = 24053484}}</ref> The amount of lung pressure needed to begin phonation is defined by Titze as the oscillation threshold pressure.<ref name=":0" /> During glottal closure, the air flow is cut off until breath pressure pushes the folds apart and the flow starts up again, causing the cycles to repeat.<ref name="McKinney"/>
The textbook entitled [[Myoelastic Aerodynamic Theory of Phonation]]<ref name="Titze, I. R. 2006"/> by [[Ingo Titze]] credits Janwillem van den Berg as the originator of the theory and provides detailed mathematical development of the theory.