• Pitch Elements
  • Pitch
  • Melody
  • Scales
  • Harmony
  • Keys
• Time Elements
  • Beat and Meter
  • Rhythm
• Expression and Organization
  • Expression Markings
  • Basics of Form
  • Form in Popular and Art Music
• Instruments and Voices
  • Timbre
  • Instrument Families
  • Voices
  • Ensembles
• Advanced Music Theory
  • Intervals in Major and Minor Scales
  • Intervals in the Chromatic Scale
  • Time Signatures Revisited
  • Advanced Keys and Scales
  • Harmonic Series Revisited

Pitch

One way that sounds are organized into music is by their highness or lowness, which is known as pitch. Pitches are played in patterns to create melodies, in sequence from low to high to create scales, simultaneously to create harmonies, and they are organized into major and minor keys. Before we can discuss these applications, we must first understand what pitch is, how it is notated, and how pitches relate to each other.

Pitch and Frequency

Pitch is roughly equivalent to the frequency of a sound wave. Frequencies are measured in vibrations per second, or Hertz (Hz). Higher pitches vibrate more quickly, whereas low pitches vibrate more slowly. It should be noted, however, that frequency is a physical property of sound, whereas pitch is a perceived phenomenon that requires interpretation by the brain. Thus, although they are closely related, pitch and frequency are not synonyms. If you would like to learn more about the physics of sound, see the list of external links.

Tuning

Tuning is the process of matching pitches precisely with each other. Simply playing the "right" note doesn't always mean that the pitch matches perfectly with the other players. Instruments are affected by moisture, temperature, and time, and they must be tuned to account for the small rise or fall in pitch that these factors can cause. String instruments use tuning pegs to tighten or loosen the strings, for example, and woodwind and brass players can extend or reduce the length of their instruments by making slight adjustments at the places where sections of their instruments join.

Before performing, every instrumental music group must tune, whether it be an orchestra, a jazz band, or a rock band. We will discuss these performing groups in more detail in the section on ensembles. Singers, too, must listen carefully to the other performers to ensure that they are singing precisely the same pitch as the others, or they will be considered out of tune.

The Staff, Clefs, the Grand Staff, and Middle C

Different pitches are indicated in musical notation by moving notes up and down on the staff (five horizontal lines). The higher the note, the higher it is placed on the staff.

When an instrument can play a very wide range of pitches (like a piano), it requires two staves, or a grand staff. At the far left of the two staves are two different clefs - on top is a treble clef, and on the bottom is a bass clef. Clefs tell us the range of pitches that can be represented on the staff lines. A treble clef is used for high pitches and a bass clef is used for low pitches.

Middle C falls between the treble and bass clefs. It can be notated above the bass clef or below the treble clef on its own little line, a ledger line. Ledger lines can be used for pitches that fall above or below the staff, but notes on ledger lines can be more difficult to read than notes within the staff, so it is best to use the clef that allows the majority of pitches to be notated within the staff.

Middle C is also used as a reference point to compare the highness or lowness of other pitches. Middle C falls in the middle of a piano keyboard, and is towards the bottom range of a high female voice (a soprano), and in the upper range of a low male voice (a bass). See the page on voices for more on voice parts.

For instruments with smaller ranges, a single staff with one clef is sufficient. Lower instruments that tend to play below middle C (like the cello or tuba) will use the bass clef, while higher instruments that usually play above middle C (like the flute or violin) will use the treble clef.

Intervals

An interval is the distance between two pitches. Intervals can occur between pitches sounded one after another (melodic intervals) or between pitches sounded simultaneously (harmonic intervals). We will cover melody and harmony specifically in a later section, but for now we will consider the basic principles of intervals.

Accidentals, Half Steps, and Whole Steps

Sharps, flats, and natural signs (naturals) are collectively called accidentals. Accidentals alter pitches by moving them up or down by the smallest interval in the Western system: a half step. A sharp raises a pitch by a half step, a flat lowers a pitch by a half step, and a natural negates the effect of a sharp or flat sign, returning the note to its default pitch.

Let's look more closely at the half step. Using the keys of a piano as an example, notice that the interval between any white key and an adjacent black key is one half step (example: C and C-sharp ). But be careful! The interval between two white keys that do not have a black key between them (B and C , E and F ) is also a half step. In order to create a whole step, we need to go two half steps (example: C to D, E to F-sharp).

Half steps and whole steps are the building blocks for scales, which we will cover in a later section.

Enharmonic Equivalence

You may have noticed on the keyboard that all of the black keys are labeled with two pitch names (example: C-sharp/D-flat). This is a result of enharmonic equivalence, which is the principle that any pitch can have more than one name. C-sharp and D-flat, for example, are the same pitch. It is easy to think of them as musical homophones - they may be spelled differently, but they sound the same. Although they are not indicated on the keyboard shown here, it is also possible to have C-flat (same as B), B-sharp (same as C), F-flat (same as E), and E-sharp (same as F), but these are not very common. Double flats and sharps are also possible, and they simply raise or lower a pitch by two half steps (one whole step), but double accidentals are also uncommon.

Octaves

On the keyboard you can see that the pitches are named with seven letters of the alphabet: A, B, C, D, E, F, and G. There are only seven because they repeat, as on the white keys of the keyboard. An octave is the distance between any pitch and the next highest or lowest pitch of the same name (examples: D to D, F-sharp to F-sharp).

At first it may seem confusing that some pitches share the same name, but there is an acoustic principle recognized in all cultures that keeps the system orderly: octave equivalence. This is the principle that every pitch with the same name sounds like a higher or lower duplication of every pitch of that name. That is, every C sounds like a duplication of every other C, just higher or lower. This is because the frequencies of these notes are related by a 2:1 ratio. For example, the A above middle C occurs at 440 Hz, therefore the A one octave higher occurs at 880 Hz, and the A one octave lower occurs at 220 Hz.

In the example below you will hear examples of octave equivalence. First will be three examples of notes an octave apart, then you will hear a phrase from the American National Anthem played in two different octaves, first separately, then simultaneously. As you listen to the excerpt, notice that the melody from the National Anthem sounds equivalent - not identical but equivalent - in either octave. When both the higher and lower octave versions of the melody are played simultaneously, they are almost indistinguishable from each other.

More Intervals

So far, we have discussed the half step, the whole step, and the octave. It is important to note that there are many other intervals that can be made between two pitches. For the sake of completeness, here is a chart showing the names and sizes (in half steps) of all the intervals that can occur within an octave. Note that the 4th and 5th are called 'perfect' rather than major or minor. In addition to the 4th and 5th, unisons and octaves are also considered perfect intervals. The reason for this label has to do with the harmonic series, so we will cover that in a later section.

For more on intervals, see intervals in major and minor scales and intervals in the chromatic scale.