A mezzo soprano is the middle vocal range for women, comparable to the baritone range among men. The word mezzo means medium or middle in Italian, and usually refers to female singers with characteristics of both alto and soprano singers. The classic mezzo soprano has the ability to reach high notes, usually up to the C two octaves above middle C, while retaining a richer timbre of voice similar to that of a deeper-ranged alto.

The distinction between sopranos and mezzo sopranos became necessary during the 18th century as musical composition drew away from using mostly male voices. They were originally used to fill secondary roles, particularly those of coquettish characters called soubrettes. An ideal mezzo possesses a range of at least three octaves, and has a darker, richer voice than most sopranos.

Mezzo sopranos are further divided into three groups based on the relative richness and range of their voices. Coloratura mezzos are generally strongest near the top of their range, and can often sing as high as sopranos. Lyrical mezzos are the most common of the three groups and are most comfortable in the middle area of their range. Dramatic mezzos are closely related to altos, and have very deep, rich, singing voices that can still reach upper registers.

Coloratura mezzo sopranos operate a unique position in most compositions. Until the 18th century, operas often included roles for countertenor castrati, men who had been castrated before puberty to retain their higher voices. After the trend fell out of fashion, coloratura mezzos and sometimes lyrical mezzos stepped in to fill these roles, as not only the range but the quality of their voices was often similar to countertenors.

If an opera specifies a trousers role, or a role traditionally played by a woman dressed as a man, the part is normally filled by a lyrical mezzo soprano. Oberon in Benjamin Brittan’s A Midsummer Night’s Dream, and Cherubino in Mozart’s The Marriage of Figaro are famous roles usually played by lyrical mezzos. Of the few lead roles written for mezzo sopranos, most play to the lyrical mezzo’s strengths.

Large roles for the mezzo soprano in opera are often limited, with heroine or lead roles rarely being written for a mezzo. Most often, mezzos in opera are play villains, enchantresses, witches, or middle-aged women. This operatic typecasting is often frustrating to mezzo sopranos, some of whom are capable of singing soprano or alto roles. One of the most famous operatic heroes is a mezzo soprano however, in Bizet’s Carmen. The role of Carmen is sought after by many aspiring mezzo sopranos as their biggest chance to prove themselves and their talent.

In choirs, mezzo sopranos are usually called second sopranos and are used to varying degrees. If the choir is sufficiently advanced enough, pieces with six or eight part harmony will include a mezzo soprano part. Otherwise, mezzos are generally divided between soprano and alto parts, able to add a darker timbre to the higher registers or broader range to the lower as needed.