Opera is a complex performance art, intended to create a type of illusion by the combination of the various arts that are part of it. However, in opera, the voices above all touch audiences. The sign of a great singer is his/her ability to use a superior voice to communicate the message and emotion contained in the text and music.

When a musician delights their audience, few listeners are aware of the technical work and challenges that must be overcome to produce a beautiful sound, and that is just fine. The voice, however, inspires a particular fascination, because it is an instrument that everyone posses, and it depends on the physical and emotional state of the artist. The presence of language (and vowels) is another aspect that distinguishes the voice from other musical instruments, since the colour or tone can be modulated according to the musical requirements of the text. Opera requires a voice that can dominate an orchestra and that can be heard in a hall with from 1,000 to 3,500 seats according to the cities (Quebec City: 1,800 seats).

The creation of such a voice requires years of training. Unlike athletes and musicians, singers usually reach their maturity after the age of 25, and their careers can last for a quarter of a century or more.
Training a voice is one of the most demanding artistic undertakings, since its mechanism is hidden.

Voices are classed in six major categories: sopranomezzo-soprano and contralto for female voices and tenorbaritone and bass for male voices. However, within these categories several variations can be found as determined by various factors as the type of role, the tone, the strength and the voice’s degree of agility. Range, versatility, tone and strength are the four essential terms to understand the variations from one category to another. The range is defined as being the register of notes covered by the voice, from extremely low to extremely high. The tone is the very colour of the voice, and is related to its vibratto qualities, power or versatility as related to the vocalisations.

Often typical types of roles will be associated to the three types of voices – high, medium, and low.

Soprano: there are several types of sopranos: the coloratura soprano which is a light, very high, very agile voice (like Olympia (the mechanical doll) in The Tales of Hoffmann by Offenbach); the soubrette has a supple voice that is comfortable in the high ranges (Susanna in The Marriage of Figaro by Mozart); the lyric soprano, more frequent, warmer, stronger, the range of which is a bit lower (Marguerite in Faust by Gounod, Mimi in La Bohème by Puccini, Violetta in La Traviata by Verdi); the spinto soprano or lirico-spinto soprano essentially a lyrical voice with more dramatic qualities and a certain bite at dramatic points (Aida by Verdi); and finally the dramatic soprano, a generally more powerful voice over the whole range, it is a generous and energetic voice.

Mezzo-soprano: a voice with a range between a contralto and a soprano. A high mezzo-soprano voice is often identical to a dramatic soprano or a spinto soprano and numerous roles can be sung by either one or the other. the coloratura mezzo-soprano is a low warm voice with agile high notes (Rosina in The Barber of Seville by Rossini), the dramatic mezzo-soprano has a strong medium register, a generous high range and generally a larger, stronger voice (Amnéris in Aida by Verdi).

Contralto (low): the lowest female voice, its range covers two octaves. It is characterised by a dark rich sound and a generous, noble tone. Despite an apparent heaviness, the contralto may be agile.

Haute-contre: this type of voice is a French speciality where a masculine voice has a higher range than a tenor where the vocalisations originate in both the chest and head. This voice, very popular in the eighteenth century, is coming back into fashion.

Countertenor: this male voice is an English speciality, mostly seen in the early music repertoire. Here, falsetto is developed in the mezzo-soprano range.

Tenor: the leggero tenor usually portrays kind roles, where there is little drama and is more tender than passionate (Almaviva in The Barber of Seville by Rossini). This voice must be agile and be able to vocalise easily. The dramatic tenor has a strong voice with a powerful medium range and bright upper register. They excel in expressing violent, heroic and wretched emotions. Sweetness and charm are almost always forbidden since it is hard for this type of voice to produce high notes other than in full force. The heroic tenor (heldentenor) has the same range as a dramatic tenor but the tonality is different. Here the voice is much more flexible and it has a greater ability to reach high notes softly.   (Don José in Carmen, Des Grieux in Manon)

Baritone: a masculine voice whose range is between bass and tenor. The baritone voice varies between the dramatic baritone (Verdi), a rich, round, edgy and vibrant voice to the light baritone, close to a tenor voice, sometimes called a baryton-Martin, which offers medium volume, but is distinguished by an enveloping sound where high notes are reached with lightness and ease. The bass-baritone is a range that is a bit higher than a bass, but that remains low. Its range is wider than a Verdi-baritone and in the higher register has a handsome and virile brilliance.

Bass: the lowest of masculine voices and can vary considerably. The basso bouffo is a comic, voluble and expressive voice (Bartolo in The Barber of Seville by Rossini). The basso cantante is in between the baritone and the basso profondo. It is a smooth voice that despite it majestic character can easily handle rapid vocalisations. The basso profondo covers two octaves and begins very low. This massive, heavy voice is stable and strong and provides a solid base for vocal ensembles (Zarastro in The Magic Flute by Mozart).