<P> In music theory, a scale is any set of musical notes ordered by fundamental frequency or pitch . A scale ordered by increasing pitch is an ascending scale, and a scale ordered by decreasing pitch is a descending scale . Some scales contain different pitches when ascending than when descending, for example, the melodic minor scale . </P> <P> Often, especially in the context of the common practice period, most or all of the melody and harmony of a musical work is built using the notes of a single scale, which can be conveniently represented on a staff with a standard key signature . </P>

A series of single notes ascending or descending is called a