Editing Vibrato (section)

===Singing===
There are three different voice vibrato processes that occur in different parts of the vocal tract. Peter-Michael Fischer has vibrato types defined by place of production:
* The [[Thyroarytenoid muscle|vocalis muscle]] vibrates at a frequency of 6.5 to 8 [[Hertz|Hz]].
* The [[Thoracic diaphragm|diaphragm]] vibrates at a frequency below 5&nbsp;Hz vibrato
* A combination of the two, resulting in a vibrato whose frequency is between 5 and 6.5&nbsp;Hz vibrato. Fischer writes:
{{blockquote | "This combination is relatively stable in the most beautiful voices. An important feature is that the partial functions can appear during the song as "accents": In the context of the presentation expressive wave dominates respirativa, lyrical character, but in an accelerated, or glottis wave, hard feature heroic, but in a slow way."|Peter-Michael Fischer.<ref>Fischer, Peter-Michael: ''Die Stimme des Sängers''. Wiesbaden: Metzler, 1993, p. 163.</ref>}}Some studies have shown that vibrato is the result of a neuromuscular tremor in the vocal folds. In 1922, Max Schoen was the first to make the comparison of vibrato to a tremor due to the following similarities:
* Vibrato and tremors have a change in amplitude 
* Both occur when the muscles are under strain 
* Neither are under the automatic control of the person
* Vibrato and tremors occur at half the rate of normal muscular discharge<ref>{{Cite book|url=https://books.google.com/books?id=rVFQdViY7jAC&q=max+schoen+vibrato+neuro+muscular+tremor&pg=PA139|title=Bel Canto: A History of Vocal Pedagogy|last=Stark|first=James|date=2003|publisher=University of Toronto Press|isbn=9780802086143|language=en}}</ref>