Alto

An alto is the second highest voice type in choral music, with a vocal range below that of the soprano, typically from the extremes, "low G" (G3) to "high F" (F5) in choral music. As well as being the modern Italian word for "high", in the present context it is an Italian abbreviation derived from the Latin phrase contratenor altus, used in medieval polyphony, usually to describe the highest of three parts, the line of which was in counterpoint (in other words, against = contra) with the tenor (which "held" the main melody; this word itself originates in the Latin verb tenere, meaning "to hold").

Alto, contralto, or mezzo-soprano?

Contralto and alto are not the same term. Technically, "alto" is not a voice type but a designated vocal line in choral music based on vocal range. The range of the alto part in choral music is usually more similar to that of a mezzo-soprano than a contralto. However, in many compositions the alto line is split into two parts. The lower part, Alto 2, is usually more suitable to a contralto voice than a mezzo-soprano voice, which may sing Alto 1.

Range

The range of an alto section, as with any other vocal section, can vary greatly from ensemble to ensemble and from vocalist to vocalist. While soloists can often be expected to exceed the range of their full section when employed, the section as a whole is usually confined to a more comfortable range to accommodate those individual members whose ranges do not encompass the full extended range of others.

Lower Range

Although altos can be written down to the G below the treble staff (G3), many "altos" are mezzo-sopranos in disguise and have a tendency to get gravely and heavy in this low range. A safe bet is to stick to low B, however A is deemed a manageable limit. When working with Alto 2's in particular in a split situation, the A and G are fair game, as long as this range isn't overused, as it can be exhausting. Typically F is the lower limit.

Upper Range

As a general rule, altos shouldn't be expected to exceed C5, except for maybe a D or two but mostly only in the Alto 1's in split situations. Remember that Alto 2's may only be comfortable up to A4. Typically F5 is the very highest note to be expected of a alto and should not be exceeded if writing for true altos.