American Standard Pitch Notation and Pitch versus Pitch Class

In order to discuss specific notes, or pitches, we will use American Standard Pitch Notation, abbreviated ASPN. ASPN designates specific musical pitches by combining a note name (such as C) with a subscript octave designation (such as 4), creating a bipartite label (for example, C₄). ASPN labels are very useful, since they can identify every possible musical note within human hearing range, from the lowest pitches to the highest.

The Reading Clefs chapter introduced octave equivalence, the concept that explains why notes one or more octaves apart have the same letter name. Music theorists distinguish between a pitch, a discrete tone with an individual frequency (e.g. C₄ using ASPN), versus a pitch class, which is less specific (e.g., C in general). A pitch class includes all the pitches with the same letter name, in any octave, along with their enharmonic equivalents. For example, all Cs are the same pitch class, and the enharmonically equivalent notes D𝄫 and B♯ are also part of the C pitch class. In this chapter we are naming specific pitches with ASPN.

ASPN and Octave Designations

ASPN differentiates between octaves, beginning with the pitch C and ending with the pitch B. This means that each new octave designation begins on the note C, as seen in Example 1. The octaves are labeled from lowest to highest, beginning with 0 and continuing in numerical order (1, 2, 3, etc.). The pitch middle C is C₄, which is useful to memorize.

All letter names within an octave (below the C of the next octave) receive the same octave designation. For example, all of the notes in Example 2 would be designated in the 4 octave, because they are above C₄ but below C5. Accidentals applied to a note do not have an effect on its ASPN number. For example, B♯₃ and C₄ have different octave numbers despite being enharmonically equivalent, because the B♯ is still considered part of the lower octave.

ASPN and the Keyboard

ASPN labels are very helpful for finding specific notes on the piano keyboard. Example 3 depicts a piano keyboard with each octave labeled using ASPN notation. As you can see, the piano keyboard spans the full octaves 1 to 7. It also contains a small part of both octaves 0 and 8. ASPN labels are the same regardless of instrument or voice type. In other words, a C₄ will always be labeled as such regardless of whether it is produced with a flute, trombone, violin, or voice.

ASPN and Staff Notation

Example 4 shows ASPN labels for common notes in the treble, bass, alto, and tenor clefs. Memorizing the location of C₄ in each clef can make finding ASPN labels quicker and easier.

Example 4. ASPN labels for notes in four clefs.

• “Pitches, Pitch Classes, Octave Designation, Enharmonic Equivalence” (YouTube)
• Tutorial on ASPN Octave Labels (liveabout.com)
• Tutorial on ASPN Octave Labels (flutopedia.com)
• Helpful Graphic with ASPN Labels on the Grand Staff and Piano (Music Theory Tips)
• Flash Cards with ASPN Labels in Treble and Bass Clefs (quizlet.com)

1. ASPN Labels and Staff Notation (.pdf)
2. ASPN Labels, pp. 23, 27, and 28 (.pdf)

1. Writing and Identifying ASPN Labels (.pdf, .docx)