There are many methods for labeling pitches, and these vary based on language of origin, style of music, pedagogy, and analytical purposes. In this textbook, we will primarily reference the widely-used English-language notation system that employs seven letter names and accidentals. This system is discussed below and is sufficient for differentiating between pitches in diatonic tonality. (If the terms diatonic and tonality don’t mean anything to you yet, don’t worry; we’ll cover those terms in later units.)
This course assumes that you have a basic knowledge of how to raise and lower pitches in standard music notation. If you need to review accepted usage of accidentals, please refer to the Further Reading section under Discussion 1b.
When studying tonal harmony, C-sharp and D-flat have unique functions and are not interchangeable, however, when considering their physical properties, there is no difference between these two pitches meaning that we consider these two pitches to be enharmonically equivalent. At its core, enharmonic equivalence is an easy concept: When two pitches sound the same–meaning that they share identical frequencies–but have different note names (i.e. letters), we consider them to be enharmonically equivalent.
If you were to group all pitches that are enharmonic equivalents, you create a pitch class; such as C-sharp, D-flat, and B-double-sharp. There are twelve pitch classes in traditional Western tonality. Every pitch has multiple enharmonic equivalents, but some are used less frequently due to the necessity for uncommon accidentals such as double-sharps and double-flats. Note that all but one pitch class has at least three enharmonic equivalents when using the five most common accidentals: naturals, flats, sharps, double-flats, and double-sharps. (The remaining pitch class only has two possible enharmonic equivalents, unless you were to use accidentals that would never appear in performable music such as triple-sharps or triple-flats.)
In the example below, each measure contains two notes that are enharmonically equivalent. Using this example, determine:
Using the example above, you can extrapolate which pitch classes have three enharmonic equivalents and which have two.
Two examples of complete enharmonic equivalent groups would be:
Each pitch in these groups belong to the same pitch class, because they share an identical frequency. Yet they function differently within the context of music, so we have multiple ways of labeling the same frequency.
This shows that the letter system employed in staff notation is the limiting factor in creating enharmonic equivalents within a pitch class. The pitch class that includes A-flat is isolated from its neighbors in such a way that there is no pitch that uses the letter F or B to create a third enharmonic equivalent when using only the five common accidentals. The interaction between the 7 letter names and 12 pitch classes is the basis for our musical notation system and will be critical in how we label intervals, chords, and scales.
When labeling pitches, we also need a way to refer to specific octaves or registers. We will be using the system used by the International Standard Organization (ISO). In this system, each pitch is given an Arabic numeral that designates its octave. For example, middle C is labeled as C4.
Using the example below, determine:
There are a few simple rules to label octaves using the ISO system.
This is almost entirely related to the evolution of the musical notation system and how the non-accidental pitches (i.e. “white keys” of the keyboard) form a major scale. While this is a fascinating topic, it is somewhat beyond the purview of this chapter, but I hope you will explore this further on your own.