Voice type

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A voice type classifies a singing voice by vocal range, vocal weight, tessitura, vocal timbre, vocal transition points ( passaggia ) like breaks and lifts, and vocal register. [1] Voice classification was developed for European classical music and seldom applies to other kinds of singing; voice classification is in the opera to pair roles with voices. Several different voice classification systems are available to identify voice types, including the German Fach system and the choral music system among many others; no system is universally applied or accepted. [2]

Singing act of producing musical sounds with the voice

Singing is the act of producing musical sounds with the voice and augments regular speech by the use of sustained tonality, rhythm, and a variety of vocal techniques. A person who sings is called a singer or vocalist. Singers perform music that can be sung with or without accompaniment by musical instruments. Singing is often done in an ensemble of musicians, such as a choir of singers or a band of instrumentalists. Singers may perform as soloists or accompanied by anything from a single instrument up to a symphony orchestra or big band. Different singing styles include art music such as opera and Chinese opera, Indian music and religious music styles such as gospel, traditional music styles, world music, jazz, blues, gazal and popular music styles such as pop, rock, electronic dance music and filmi.

Human voice sound made by a human being using the vocal folds for talking, singing, laughing, crying, screaming, etc

The human voice consists of sound made by a human being using the vocal tract, such as talking, singing, laughing, crying, screaming, etc. The human voice frequency is specifically a part of human sound production in which the vocal folds are the primary sound source.

Vocal range is the measure of the breadth of pitches that a human voice can phonate. Its most common application is within the context of singing, where it is used as a defining characteristic for classifying singing voices into groups known as voice types. It is also 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, although it has little practical application in terms of speech.

Contents

Voice classification is a tool for singers, composers, venues, and listeners to categorize vocal properties and to associate roles with voices. While choral singers are classified into voice parts based on their vocal range, solo singers are classified into voice types based more on their tessitura – where their voice feels most comfortable for the majority of the time. [3]

A singer will choose a repertoire that suits his or her instrument. Some singers such as Enrico Caruso, Rosa Ponselle, Joan Sutherland, Maria Callas, Ewa Podleś, or Plácido Domingo have voices that allow them to sing roles from a wide variety of types; some singers such as Shirley Verrett or Grace Bumbry change type and even voice part over their careers; and some singers such as Leonie Rysanek have voices that lower with age, causing them to cycle through types over their careers. Some roles as well are hard to classify, having very unusual vocal requirements; Mozart wrote many of his roles for specific singers who often had remarkable voices, and some of Verdi's early works make extreme demands on his singers. [4]

Enrico Caruso Italian operatic tenor

Enrico Caruso was an Italian operatic tenor. He sang to great acclaim at the major opera houses of Europe and the Americas, appearing in a wide variety of roles from the Italian and French repertoires that ranged from the lyric to the dramatic. Caruso also made approximately 260 commercially released recordings from 1902 to 1920. All of these recordings, which span most of his stage career, remain available today on CDs and as downloads and digital streams.

Rosa Ponselle American operatic soprano

Rosa Ponselle was an American operatic soprano with a large, opulent voice. She sang mainly at the New York Metropolitan Opera and is generally considered by music critics to have been one of the greatest sopranos of the past 100 years.

Joan Sutherland Australian soprano

Dame Joan Alston Sutherland, OM, AC, DBE was an Australian-born coloratura soprano noted for her contribution to the renaissance of the bel canto repertoire from the late 1950s through to the 1980s.

Number of voice types

Many different voice types are used in vocal pedagogy in a variety of voice classification systems. Most of these types, however, are grouped into seven major voice categories that are, for the most part, acknowledged across the major voice classification systems. Women are typically divided into three groups: soprano, mezzo-soprano, and contralto. Men are usually divided into four groups: countertenor, tenor, baritone, and bass. When considering the pre-pubescent voice, an eighth term, treble, is applied. Within each of these major categories, subcategories identify specific vocal qualities such as coloratura facility and vocal weight to differentiate between voices. [5] The vocal range of classical performance covers about five octaves, from a low G1 (in scientific pitch notation) to a high G6, although the extremes are rare. More commonly the range is from a low C2 to a high D6. Any individual's voice can perform over a range of one and a half to more than two octaves. Vocal ranges are grouped into overlapping types that each span about two octaves. Many singers fall between groups and can perform some parts in either type.

Vocal pedagogy

Vocal pedagogy is the study of the art and science of voice instruction. It is used in the teaching of singing and assists in defining what singing is, how singing works, and how proper singing technique is accomplished.

A soprano[soˈpraːno] is a type of classical female singing voice and has the highest vocal range of all voice types. The soprano's vocal range (using scientific pitch notation) is from approximately middle C (C4) = 261 Hz to "high A" (A5) =880 Hz in choral music, or to "soprano C" (C6, two octaves above middle C) =1046 Hz or higher in operatic music. In four-part chorale style harmony, the soprano takes the highest part, which often encompasses the melody. The soprano voice type is generally divided into the coloratura, soubrette, lyric, spinto, and dramatic soprano.

A mezzo-soprano or mezzo (, ; Italian: [ˈmɛddzo soˈpraːno] meaning "half soprano") is a type of classical female singing voice whose vocal range lies between the soprano and the contralto voice types. The mezzo-soprano's vocal range usually extends from the A below middle C to the A two octaves above (i.e. A3–A5 in scientific pitch notation, where middle C = C4; 220–880 Hz). In the lower and upper extremes, some mezzo-sopranos may extend down to the F below middle C (F3, 175 Hz) and as high as "high C" (C6, 1047 Hz). The mezzo-soprano voice type is generally divided into the coloratura, lyric, and dramatic mezzo-soprano.

Female voices

Soprano

Soprano voice range (C4-C6) indicated on piano keyboard in green with dot marking middle C (C4) Soprano voice range on keyboard.svg
Soprano voice range (C4–C6) indicated on piano keyboard in green with dot marking middle C (C4)

Soprano range: The soprano is the highest singing voice. The typical soprano voice lies between C4 (middle C) and C6 (high C). The low extreme for sopranos is roughly A3 (just below middle C). [5] Most soprano roles do not extend above C6 although there are several standard soprano roles that call for D6. At the highest extreme, some coloratura soprano roles may reach to G6 (the G above high C). [6]

A coloratura soprano is a type of operatic soprano voice that specializes in music that is distinguished by agile runs, leaps and trills.

Soprano tessitura: The tessitura of the soprano voice lies higher than all the other voices except the sopranino. In particular, the coloratura soprano has the highest tessitura of all the soprano subtypes. [7]

Sopranino refers to a singing voice that is higher than soprano. It typically refers to a range of about E4 to E6, sometimes extending as high as G6. A sopranino voice type is rare. It is not considered a classical music part, but would be cast as a soprano.

Soprano subtypes: As with all voice types, sopranos are often divided into different subcategories based on range, vocal color or timbre, the weight of voice, and dexterity of the voice. Sopranos are often broken down into five subcategories: coloratura soprano, soubrette, lyric soprano, spinto soprano, and dramatic soprano. [7]

Two types of soprano especially dear to the French are the Dugazon and the Falcon , which are intermediate voice types between the soprano and the mezzo-soprano. A Dugazon is a darker-colored soubrette. A Falcon a darker-colored soprano drammatico. [8]

Mezzo-soprano

Mezzo-soprano voice range (A3-A5) indicated on piano keyboard in green with dot marking middle C (C4) Mezzo-soprano voice range on keyboard.svg
Mezzo-soprano voice range (A3–A5) indicated on piano keyboard in green with dot marking middle C (C4)

Mezzo-soprano range: The mezzo-soprano voice is the middle-range voice type for females; [5] it lies between the soprano and contralto ranges, over-lapping both of them. The typical range of this voice is between A3 (the A below middle C) to A5 (two octaves higher). In the lower and upper extremes, some mezzo-sopranos may extend down to F3 (the F below middle C) and as high as C6 (high C). [5]

Mezzo-soprano tessitura: Although this voice overlaps both the contralto and soprano voices, the tessitura of the mezzo-soprano is lower than that of the soprano and higher than that of the contralto.

Mezzo-soprano subtypes: Mezzo-sopranos are often broken down into three subcategories: lyric mezzo-soprano, coloratura mezzo-soprano and dramatic mezzo-soprano. [7]

Contralto

Contralto voice range (F3-F5) indicated on piano keyboard in green with dot marking middle C (C4) Contralto voice range on keyboard.svg
Contralto voice range (F3–F5) indicated on piano keyboard in green with dot marking middle C (C4)

Contralto range: The contralto voice is the lowest female voice. A true operatic contralto is rare, [9] so much so that often roles intended for contralto are performed by mezzo-sopranos. The typical contralto range lies between F3 (the F below middle C) to F5 (the second F above middle C). In the lower and upper extremes some contralto voices can sing from D3 (the D below middle C) to B5 (the second B-flat above), one whole step short of the soprano high C. [5]

Contralto tessitura: The contralto voice has the lowest tessitura of the female voices.

Contralto subtypes: Contraltos are often broken down into three subcategories: coloratura contralto, lyric contralto, and dramatic contralto. [7] A soprano sfogato is a contralto who has an extended high range reaching the soprano high C.

Male voices

Countertenor

Countertenor voice range (E3-E5) indicated on piano keyboard in green with dot marking middle C (C4) Countertenor voice range on keyboard.svg
Countertenor voice range (E3–E5) indicated on piano keyboard in green with dot marking middle C (C4)

Countertenor range: The countertenor is the highest male voice. Many countertenor singers perform roles originally written for a castrato in baroque operas. Except for a few very rare voices (such as the American male soprano Michael Maniaci or singers with a disorder such as Kallmann syndrome), singers called countertenors generally sing in the falsetto register, sometimes using their modal voice for the lowest notes. Historically, there is much evidence that the countertenor, in England at least, also designated a very high tenor voice, the equivalent of the French haute-contre . Until about 1830, all male voices used some falsetto-type voice production in their upper range. Countertenor voices span a broad range, covering E3 to E5.

Countertenor subtypes: Countertenors are often broken down into three subcategories: sopranist or "male soprano", the haute-contre, and the castrato. The last actual castrato singer, Alessandro Moreschi, died in 1922. [7]

Tenor

Tenor voice range (C3-C5) indicated on piano keyboard in green with dot marking middle C (C4) Tenor voice range on keyboard.svg
Tenor voice range (C3–C5) indicated on piano keyboard in green with dot marking middle C (C4)

Tenor range: The tenor is the highest male voice within the modal register. The typical tenor voice lies between C3 (one octave below middle C) to C5 (one octave above middle C). The low extreme for tenors is roughly B2 (the second B-flat below middle C). At the highest extreme, some tenors can sing up to F5 (the second F above middle C). [5]

Tenor tessitura: The tessitura of the tenor voice lies above the baritone voice and below the countertenor voice. The leggero tenor has the highest tessitura of all the tenor subtypes. [7]

Tenor subtypes: Tenors are often divided into different subcategories based on range, vocal color or timbre, the weight of the voice, and dexterity of the voice. Tenors are often broken down into seven subcategories: tenore contraltino , leggero tenor or tenore di grazia , lyric tenor, spinto tenor or tenore spinto, dramatic tenor, heldentenor, and baritenor. [7] Famous tenors include Enrico Caruso, Juan Diego Flórez, Alfredo Kraus, and Luciano Pavarotti.

Baritone

Baritone voice range (A2-A4) indicated on piano keyboard in green with dot marking middle C (C4) Baritone voice range on keyboard.svg
Baritone voice range (A2–A4) indicated on piano keyboard in green with dot marking middle C (C4)

Baritone range: The baritone voice is the middle-range voice type for males; it lies between the bass and tenor ranges, overlapping both of them. The typical baritone range is from A2 (the second A below middle C) to A4 (the A above middle C). A baritone's range might extend down to F2 or up to C5. The baritone voice type is the most common male voice. [5]

Baritone tessitura: Although this voice range overlaps both the tenor and bass ranges, the tessitura of the baritone is lower than that of the tenor and higher than that of the bass. [7]

Baritone subtypes: Baritones are often divided into different subcategories based on range, vocal color or timbre, the weight of the voice, and dexterity of the voice. Baritones are often broken down into nine subcategories: baryton-Martin, lyric baritone, bel canto or coloratura baritone, kavalierbariton, heldenbaritone, Verdi baritone, dramatic baritone, baryton-noble, and bass-baritone. [7]

Bass

Bass voice range (E2-E4) indicated on piano keyboard in green with dot marking middle C (C4) Bass voice range on keyboard.svg
Bass voice range (E2–E4) indicated on piano keyboard in green with dot marking middle C (C4)

Bass range: The bass is the lowest singing voice. The bass voice has the lowest tessitura of all the voices. The typical bass range lies between E2 (the second E below middle C) to E4 (the E above middle C). In the lower and upper extremes of the bass voice, some basses can sing from C2 (two octaves below middle C) to G4 (the G above middle C). [7]

Bass subtypes: Basses are often divided into different subcategories based on range, vocal color or timbre, the weight of the voice, and dexterity of the voice. Basses are often broken down into six subcategories: basso profondo, basso buffo, bel canto bass, basso cantante, dramatic bass, and bass-baritone. [7]

Children's voices

The voice from childhood to adulthood

The human voice is in a constant state of change and development just as the whole body is in a state of constant change. A human voice will alter as a person gets older moving from immaturity to maturity to a peak period of prime singing and then ultimately into a declining period. The vocal range and timbre of children's voices does not have the variety that adults' voices have. Both boys and girls prior to puberty have an equivalent vocal range and timbre. The reason for this is that both groups have a similar larynx size and weight and a similar vocal cord structure and color. With the onset of puberty, both men and women's voices alter as the vocal ligaments become more defined and the laryngeal cartilages harden. The laryngeal structure of both voices change but more so in men. The height of the male larynx becomes much greater than in women. The size and development of adult lungs also changes what the voice is physically capable of doing. From the onset of puberty, the human voice is in an in-between phase where it is not quite a child's voice nor an adult one yet. This is not to suggest that the voice stops changing after puberty. Different singers will reach adult development earlier or later than others, and as stated above there are continual changes throughout adulthood as well. [10]

Treble

Treble voice range (A3-A5) indicated on piano keyboard in green with dot marking middle C (C4) Treble voice range on keyboard.svg
Treble voice range (A3–A5) indicated on piano keyboard in green with dot marking middle C (C4)

Treble can refer to either a young female or young male singer with an unchanged voice in the mezzo-soprano range. Initially, the term was associated with boy sopranos but as the inclusion of girls into children's choirs became acceptable in the 20th century the term has expanded to refer to all pre-pubescent voices. The lumping of children's voices into one category is also practical as boys and girls share a similar range and timbre. [10]

Most trebles have an approximate range from A3 (the A below middle C) to F5 (the F one and a half octaves above middle C). Some trebles, however, can extend their voices higher in the modal register to C6 (high C). This ability may be comparatively rare, but the Anglican church repertory, which many trained trebles sing, frequently demands A5. [10] For higher notes see, for example, the treble solo at the beginning of Stanford's Magnificat in G, David Willcocks' descant to Mendelssohn's tune for the carol "Hark! The Herald Angels Sing", and the even higher treble solo in the "Nunc dimittis" from Tippett's evening canticles written for St John's College, Cambridge. Many trebles are also able to reach higher notes by use of the whistle register but this practice is rarely called for in performance. [5]

Classifying singers

Vocal pedagogues generally consider four main qualities of a human voice when attempting to classify it: vocal range, tessitura, timbre, and vocal transition points known as passaggio . However, teachers may also consider physical characteristics, speech level, scientific testing, and other factors such as vocal register. Voice classification into the correct voice type is important for vocal pedagogues and singers as a guiding tool for the development of the voice.

Mis-classification of a singer's voice type is dangerous. It can damage the vocal cords, shorten a singing career, and lead to the loss of both vocal beauty and free vocal production. Some of these dangers are not immediate ones; the human voice is quite resilient, especially in early adulthood, and the damage may not make its appearance for months or even years. Unfortunately, this lack of apparent immediate harm can cause singers to develop bad habits that will over time cause irreparable damage to the voice. [5] Singing outside the natural vocal range imposes a serious strain upon the voice. Clinical evidence indicates that singing at a pitch level that is either too high or too low creates vocal pathology. [11] According to vocal pedagogue Margaret Greene, "The need for choosing the correct natural range of the voice is of great importance in singing since the outer ends of the singing range need very careful production and should not be overworked, even in trained voices." [12] Singing at either extreme of the range may be damaging, but the possibility of damage seems to be much more prevalent in too high a classification. A number of medical authorities have indicated that singing at too high a pitch level may contribute to certain vocal disorders. Medical evidence indicates that singing at too high of a pitch level may lead to the development of vocal cord nodules. Increasing tension on the vocal cords is one of the means of raising pitch. Singing above an individual's best tessitura keeps the vocal cords under a great deal of unnecessary tension for long periods of time, and the possibility of vocal abuse is greatly increased. Singing at too low a pitch level is not as likely to be damaging unless a singer tries to force the voice down. [4]

Dangers of quick identification

Many vocal pedagogues warn of the dangers of quick identification. Premature concern with classification can result in misclassification, with all its attendant dangers. Notable vocal pedagogue William Vennard has stated, "I never feel any urgency about classifying a beginning student. So many premature diagnoses have been proved wrong, and it can be harmful to the student and embarrassing to the teacher to keep striving for an ill-chosen goal. It is best to begin in the middle part of the voice and work upward and downward until the voice classifies itself." [13] Most vocal pedagogues believe that it is essential to establish good vocal habits within a limited and comfortable range before attempting to classify the voice. When techniques of posture, breathing, phonation, resonation, and articulation have become established in this comfortable area, the true quality of the voice will emerge and the upper and lower limits of the range can be explored safely. Only then can a tentative classification be arrived at, and it may be adjusted as the voice continues to develop. [12] Many vocal pedagogues suggest that teachers begin by assuming that a voice is of a medium classification until it proves otherwise. The reason for this is that the majority of individuals possess medium voices and therefore this approach is less likely to mis-classify or damage the voice. [5]

Choral music classification

Unlike other classification systems, choral music divides voices solely on the basis of vocal range. Choral music most commonly divides vocal parts into high and low voices within each sex: soprano and alto vocal ranges for females, tenor and bass vocal ranges for males (SATB), and occasionally treble for children. As a result, the typical chorus affords many opportunities for misclassification to occur. [5] Since most people have medium voices, they are often assigned a part that is either too high or too low for them; the mezzo-soprano must sing soprano or alto and the baritone must sing tenor or bass. Either option can present problems for the singer, but for most singers there are fewer dangers in singing too low, than in singing too high. [3]

See also

Related Research Articles

Clef musical symbol used to indicate the pitch of written notes

A clef is a musical symbol used to indicate the pitch of written notes. Placed on a stave, it indicates the name and pitch of the notes on one of the lines. This line serves as a reference point by which the names of the notes on any other line or space of the stave may be determined.

A countertenor (also contra tenor) is a type of classical male singing voice whose vocal range is equivalent to that of the female contralto or mezzo-soprano voice types, generally extending from around G3 to D5 or E5, although a sopranist (a specific kind of countertenor) may match the soprano's range of around C4 to C6. Countertenors often are baritones or tenors at core, but on rare occasions use this vocal range in performance.

The musical term alto, meaning "high" in Italian, refers to the second highest part of a contrapuntal musical texture and is also applied to its associated vocal range, especially in choral music. It is also the root word of contralto, the lowest standard female voice type. When designating instruments, "alto" likewise can refer either to the corresponding vocal range or to musical role. The term "alto" is also used to designate a specific kind of musical clef; see alto clef.

Tenor is a male voice type in classical music whose vocal range lies between the countertenor and baritone. The tenor's vocal range extends up to C5. The low extreme for tenors is roughly A2 (two As below middle C). At the highest extreme, some tenors can sing up to the second F above middle C (F5). The tenor voice type is generally divided into the leggero tenor, lyric tenor, spinto tenor, dramatic tenor, heldentenor, and tenor buffo or spieltenor.

A contralto is a type of classical female singing voice whose vocal range is the lowest female voice type.

Falsetto is the vocal register occupying the frequency range just above the modal voice register and overlapping with it by approximately one octave.

A sopranist is a male singer who is able to sing in the vocal tessitura of a soprano usually through the use of falsetto vocal production. This voice type is a specific kind of countertenor. In rare cases an adult man may be able to sing in the soprano range using his normal or modal voice and not falsetto due to endocrinological reasons, like Radu Marian, or as a result of a larynx that has not completely developed as in the case of Michael Maniaci.

Passaggio is a term used in classical singing to describe the transition area between the vocal registers. The passaggi (plural) of the voice lie between the different vocal registers, such as the chest voice, where any singer can produce a powerful sound, the middle voice, and the head voice, where a powerful and resonant sound is accessible, but usually only through vocal training. The historic Italian school of singing describes a primo passaggio and a secondo passaggio connected through a zona di passaggio in the male voice and the a primo passaggio and secondo passaggio in the female voice. A major goal of classical voice training in classical styles is to maintain an even timbre throughout the passaggio. Through proper training, it is possible to produce a resonant and powerful sound.

The German Fach system is a method of classifying singers, primarily opera singers, according to the range, weight, and color of their voices. It is used worldwide, but primarily in Europe, especially in German-speaking countries and by repertory opera houses.

In music, SATB is an initialism for soprano, alto, tenor and bass, defining the voice types required by a chorus or choir to perform a particular musical work. Pieces written for SATB can be sung by choruses of mixed genders, by choirs of men and boys, or by four soloists.

A soubrette is a type of operatic soprano voice fach, often cast as a female stock character in opera and theatre. The term arrived in English from Provençal via French, and means "conceited" or "coy". A soubrette is also defined as a young woman regarded as flirtatious or frivolous.

The tenore contraltino is a specialized form of the tenor voice found in Italian opera around the beginning of the 19th century, mainly in the Rossini repertoire, which rapidly evolved into the modern 'Romantic' tenor. It is sometimes referred to as tenor altino in English books.

In music, an extension is a set of musical notes that lie outside the standard range or tessitura.

There is no authoritative system of voice classification in non-classical music as classical terms are used to describe not merely various vocal ranges, but specific vocal timbres unique to each range. These timbres are produced by classical training techniques with which most popular singers are not intimately familiar, and which even those that are do not universally employ.

Soprano sfogato is a contralto or mezzo-soprano who is capable—by sheer industry or natural talent—of extending her upper range and being able to encompass the coloratura soprano tessitura. An upwardly extended "natural" soprano is sometimes called soprano assoluto.

A bass ( BAYSS) is a type of classical male singing voice and has the lowest vocal range of all voice types. According to The New Grove Dictionary of Opera, a bass is typically classified as having a vocal range extending from around the second E below middle C to the E above middle C (i.e., E2–E4). Its tessitura, or comfortable range, is normally defined by the outermost lines of the bass clef. Categories of bass voices vary according to national style and classification system. Italians favour subdividing basses into the basso cantante (singing bass), basso buffo ("funny" bass), or the dramatic basso profondo (low bass). The American system identifies the bass-baritone, comic bass, lyric bass, and dramatic bass. The German fach system offers further distinctions: Spielbass (Bassbuffo), Schwerer Spielbass (Schwerer Bassbuffo), Charakterbass (Bassbariton), and Seriöser Bass. These classification systems can overlap. Rare is the performer who embodies a single fach without also touching repertoire from another category.

References

  1. Shewan, Robert (January–February 1979). "Voice Classification: An Examination of Methodology". The NATS Bulletin . 35: 17–27.
  2. Stark, James (2003). Bel Canto: A History of Vocal Pedagogy. University of Toronto Press. ISBN   978-0-8020-8614-3.
  3. 1 2 Smith, Brenda (2005). Choral Pedagogy. Plural Publishing. ISBN   978-1-59756-043-6.
  4. 1 2 Appelman, D. Ralph (1986). The Science of Vocal Pedagogy: Theory and Application. Indiana University Press. ISBN   978-0-253-20378-6.
  5. 1 2 3 4 5 6 7 8 9 10 11 McKinney, James (1994). The Diagnosis and Correction of Vocal Faults. Genovex Music Group. ISBN   978-1-56593-940-0.
  6. Coffin, Berton (1960). Coloratura, Lyric and Dramatic Soprano, Vol. 1. Rowman & Littlefield. ISBN   978-0-8108-0188-2.
  7. 1 2 3 4 5 6 7 8 9 10 11 Boldrey, Richard (1994). Guide to Operatic Roles and Arias. Caldwell Publishing. ISBN   978-1-877761-64-5.
  8. Voice Classification Archived 2007-11-04 at the Wayback Machine
  9. Myers, Eric, "Sweet and Low: The case of the vanishing contralto Archived 2011-07-18 at the Wayback Machine , Opera News , December 1996.
  10. 1 2 3 PowerPoint Presentation Archived 2008-09-08 at the Wayback Machine
  11. Cooper, Morton (1973). Modern Techniques of Vocal Rehabilitation. Charles C. Thomas. ASIN   B000JC1U76.
  12. 1 2 Greene, Margaret; Lesley Mathieson (2001). The Voice and its Disorders (6th ed.). John Wiley & Sons. ISBN   978-1-86156-196-1.
  13. Vennard, William (1967). Singing: The Mechanism and the Technic. Carl Fischer. ISBN   978-0-8258-0055-9.

Further reading