Start by learning the chromatic scale. The chromatic scale consists of 12 pitches starting with A-flat and ending on G. Use a reference chart to identify the pitches of the chromatic scale.
Learn the names of the musical intervals. There are 12 basic intervals you will use to identify voice measurements: minor and major seconds, minor and major thirds, perfect fourth, tritone, perfect fifth, minor and major sixths, minor and major sevenths and finally, the octave.
Learn about the distance between each interval. A minor second is one half-step, which is the distance between two notes on the chromatic scale. For instance, a minor second above C would be Db. Each interval after that adds one half-step to the measurement. For instance, a major second is two half-steps, a minor third is three, a major third is four and a perfect fourth is five; this continues all up to the octave.
Learn about the distance between each interval. A minor second is one half-step, which is the distance between two notes on the chromatic scale. For instance, a minor second above C would be Db. Each interval after that adds one half-step to the measurement. For instance, a major second is two half-steps, a minor third is three, a major third is four and a perfect fourth is five; this continues all up to the octave.
Obtain the sheet music for the voice you wish to create measurements. Measure the distance between each pitch by calculating the interval from one pitch to the next. For example, if there is a C followed by an F, the interval is a perfect fourth.