To understand the Soprano part it is imperative that you first understand vocal range. Technically, vocal range is “the measure of the breadth of pitches that a human voice can phonate.” * In layman’s terms vocal range is the musical notes that a person can sing. Vocal range encompasses all of the musical notes that a person can sing from the lowest note to the highest. The highest of the vocal ranges is the Soprano and it is in most cases, especially in the choir, sung by females.
Typically, the Soprano range is from middle C on the piano (also referred to as C4 not to be confused with the explosive) up to two octaves above middle C or C6. In some cases the individual may be able to sing higher or lower or even both but the Soprano range is going to fall within this span. The Soprano part is usually the melody or lead part with the exception of harmony inversions where one of the other parts would take the lead and the Soprano would switch to a harmony part. When the lead part is sung by a male in a quartet it is sung an octave lower.
When referring to Soprano, most all of the time, especially as it relates to Choral or Choir sheet music it is referencing the voice classification. It should also be noted that in referring to Choral or Choir the terms are sometimes used interchangeably, but as a general rule of thumb, Choral or Chorus is usually related to a theatrical group of singers whereas Choir almost always refers to a Church Choir or a religious themed group of singers.
It is common in England in Choral music for males to sing the Soprano in the typical Soprano range using their falsetto voice. In this case, they are either referred to as countertenors or sopranists.
In choir as well as choral music, often referred to as SATB sheet music (for Soprano, Alto, Tenor, Bass) the term Soprano does not necessarily refer to the type of voice but instead refers to a vocal part or voice classification. The term voice classification is by and large related to opera and was developed within the realms of classical music for the purpose of evaluating and designating voice type. There are several other things such as timbre, vocal weight and tessitura to consider but the first thing in determining the voice type is to determine the voice range.
The Soprano voice is most commonly a bright toned high pitched voice. True Sopranos are vocally weaker in their middle voice and much stronger on the upper end of their register.
The untrained vocalist will usually be more limited on their vocal range both on the top and bottom end of their vocal register but can improve and extend this range with proper training.
In standard SATB notation and in most songs arranged for Choir as well as the Old Red Back Church Hymnal the Soprano note is the top note of the Treble or G clef. If you have the ability to read music then sit down and examine a piece of standard SATB sheet music and you will discover that the top note of the Treble clef, the Soprano part, will usually fall in the range of middle C (C4) up to the C6.