Vocal range is the measure of the breadth of pitches that a human voice can phonate. Although the study of vocal range has little practical application in terms of speech, it is a topic of study within linguistics, phonetics, and speech and language pathology, particularly in relation to the study of tonal languages and certain types of vocal disorders. However, the most common application of the term "vocal range" is within the context of singing, where it is used as one of the major defining characteristics for classifying singing voices into groups known as voice types.
Singing and the definition of vocal range
While the broadest definition of vocal range is simply the span from the lowest to the highest note a particular voice can produce, this broad definition is often not what is meant when "vocal range" is discussed in the context of singing. Vocal pedagogists tend to define the vocal range as the total span of "musically useful" pitches that a singer can produce. This is because some of the notes a voice can produce may not be considered usable by the singer within performance for various reasons. For example, within opera all singers must project over an orchestra without the aid of a microphone. An opera singer would therefore only be able to include the notes that they are able to adequately project over an orchestra within his or her vocal range. In contrast, a pop artist could include notes that could be heard with the aid of a microphone.
Another factor to consider is the use of different forms of vocal production. The human voice is capable of producing sounds using different physiological processes within the larynx. These different forms of voice production are known as vocal registers. While the exact number and definition of vocal registers is a controversial topic within the field of singing, the sciences identify only four registers: the whistle register, the falsetto register, the modal register, and the vocal fry register. Typically only the usable pitches within the modal register--the register used in normal speech and most singing--are included when determining singers' vocal ranges. There are, however, exceptions. In opera for example countertenors often use falsetto and coloratura sopranos frequently use the whistle register while in popular music male doo-wop singers might regularly use falsetto pitches; notes from these registers would therefore be included in the vocal ranges of these voices. 
Vocal range and voice classification
Vocal range plays such an important role in classifying singing voices into voice types that sometimes the two terms are confused with one another. A voice type is a particular kind of human singing voice perceived as having certain identifying qualities or characteristics; vocal range being only one of those characteristics. Other factors are vocal weight, vocal tessitura, vocal timbre, vocal transition points, physical characteristics, speech level, scientific testing, and vocal registration. All of these factors combined are used to categorize a singer's voice into a particular kind of singing voice or voice type.
There are a plethora of different voice types used by vocal pedagogists today in a variety of voice classification systems. Most of these types, however, are sub-types that fall under seven different major voice categories that are for the most part acknowledged across all of the major voice classification systems. Women are typically divided into three main groups: soprano, mezzo-soprano, and contralto. Men are usually divided into four main groups: countertenor, tenor, baritone, and bass. When considering the pre-pubescent voices of children an eighth term, treble, can be applied. Within each of these major categories there are several sub-categories that identify specific vocal qualities like coloratura facility and vocal weight to differentiate between voices.
Vocal range itself cannot determine a singer's voice type. While each voice type does have a general vocal range associated with it, human singing voices may possess vocal ranges that encompass more than one voice type or are in between the typical ranges of two voice types. Therefore, voice teachers only use vocal range as one factor in classifying a singer's voice. More important than range in voice classification is tessitura, or where the voice is most comfortable singing, and vocal timbre, or the characteristic sound of the singing voice. For example, a female singer may have a vocal range that encompasses the high notes of a mezzo-soprano and the low notes of a soprano. A voice teacher would therefore look to see whether or not the singer were more comfortable singing up higher or singing lower. If the singer were more comfortable singing higher, then the teacher would probably classify her as a soprano and if the singer were more comfortable singing lower, then they would probably classify her as a mezzo-soprano. The teacher would also listen to the sound of the voice. Sopranos tend to have a lighter and less rich vocal sound than a mezzo-soprano. A voice teacher, however, would never classify a singer in more than one voice type, regardless of the size of their vocal range.
The following are the general vocal ranges associated with each voice type using scientific pitch notation where middle C is written as C4. Some singers within these voice types may be able to sing somewhat higher or lower:
World records and extremes of vocal range
- Guinness lists the highest demanded note in the classical repertoire as G6 in "Popoli di Tessaglia", K. 316, a concert aria by W. A. Mozart, composed for Aloysia Weber. Though pitch standards were not fixed in the eighteenth century, this rare note is also heard in the opera Esclarmonde by Jules Massenet, Europa riconosciuta by Antonio Salieri and Les contes d'Hoffmann by Jacques Offenbach. Europa riconosciuta also demands a high F-sharp from the roles of Europa and Semele several times. The highest note commonly called for is F6, famously heard in the Queen of the Night's two arias "Der Hölle Rache kocht in meinem Herzen" and "O zittre nicht, mein lieber Sohn" in Mozart's opera Die Zauberflöte.
Several little-known works call for pitches higher than G6. For example, the soprano Mado Robin, who was known for her exceptionally high voice, sang a number of compositions created especially to exploit her highest notes, reaching C7. Robin also added a number of her top notes to other arias; when she sang "Spargi d'amaro pianto" (Lucia di Lammermoor), for example, she would use B♭6 as the penultimate note, rather than B♭5 as written.
- Lowest note in a solo: Guinness lists the lowest demanded note in the classical repertoire as D2 (almost two octaves below Middle C) in Osmin's second aria in Mozart's Die Entführung aus dem Serail. Although Osmin's note is the lowest 'demanded' in the operatic repertoire, lower notes are frequently heard, both written and unwritten, and it is traditional for basses to interpolate a low C2 in the duet "Ich gehe doch rate ich dir" in the same opera. Leonard Bernstein composed an optional B1 (a minor third below D2) in a bass aria[not specific enough to verify] in the opera house version of Candide. In a Russian piece combining solo and choral singing, Pavel Chesnokov directs the bass soloist in "Do not deny me in my old age" to descend even lower, to G1 or B♭1, depending on the arrangement. In the symphonic repertoire, the bass soloist in Mahler's Eighth Symphony is asked to sing a C♯2.
- Lowest note for a choir: Mahler's Resurrection Symphony and Eighth Symphony (bar 1457 in the "Chorus mysticus") and Rachmaninoff's Vespers require B♭1. Frederik Magle's symphonic suite Cantabile and Zoltán Kodály's Psalmus hungaricus both require A1. In Russian choirs the oktavists traditionally sing an octave below the bass part, down to G1. Kheruvimskaya pesn (Song of Cherubim) by Krzysztof Penderecki includes a written F1 in its last chord, though the note itself is seldom performed.
- The Guinness World Record for the largest vocal range is held by Tim Storms, and spans 10 octaves.
- McKinney, James (1994). The Diagnosis and Correction of Vocal Faults. Genovex Music Group. ISBN 978-1-56593-940-0.
- Appelman, D. Ralph (1986). The Science of Vocal Pedagogy: Theory and Application. Indiana University Press. ISBN 978-0-253-20378-6.
- Shewan, Robert (January–February 1979). "Voice Classification: An Examination of Methodology". The NATS Bulletin 35: 17–27.
- Stark, James (2003). Bel Canto: A History of Vocal Pedagogy. University of Toronto Press. ISBN 978-0-8020-8614-3.
- Guinness Book of Records, 2006 edition
- Schirmer's Library of Musical Classics, Vol. 1751, introduction. The G6 can be seen on p. 72
- Concise Oxford Dictionary of Opera (edited by Harold Rosenthal)[full citation needed]
- Mado Robin: "Sovra il sen" (from "Care compagne ... Come per me serena" on YouTube, from La sonnambula
- "Greatest vocal range, male". Retrieved 2013-06-25.
- A history of vocal definition
- Accurate average vocal ranges
- Singing Voice
- National Center for Voice and Speech's official website
- The Voice Foundation's official website