Names and octaves of notes

A note must define the pitch. Otherwise, it would neither define the frequency, and hence nor the tone. When we know the pitch we also understand which piano key to press to produce the proper tone. However, it is important to understand that a note defines more than just the pitch. A note defines a pitch spelling (i.e. one of a few possible pitch spellings for the same pitch). Alternatively, we can say that it defines a pitch class spelling and an octave. 

When we shall talk about notes, we shall use the term note name for the pitch spelling of a note. In the following few chapters, we shall learn how to read note names and octaves from notes written on a staff. Also, later in the book, some very important concepts, like a tonic or a chord root, will be defined as note names (not as pitch classes). Such definitions emphasize that, for instance, the tonics or chord roots G# and Ab are considered different. The following chapters will teach you reading notes and other symbols that appear often in scores. 

Name and octave of note

The name and octave of a note are determined by the position of a note on a staff, a clef, a key signature and the usage of accidentals. 

Staff

A staff is made of five horizontal lines.

Figure: A staff

A note can be positioned either on a line or a space. A position where a note can be placed is called the staff position. If a note must be positioned outside the staff positions created by the five horizontal lines, then ledger lines are used to mark the position of a note. The next figure shows notes positioned both inside the staff positions created by the five horizontal lines and outside of them, when ledger lines are used. For now, we shall use only one graphical symbol for notes, an unfilled notehead. Later, we shall learn other graphical symbols for notes. The notes are always read and played from left to right. 

Figure: Notes on a staff

Clef

A clef assigns note names and octaves to the staff positions. Each staff must have a clef. A treble clef assigns the note name G and octave 4 on the staff line that passes through the curl of the treble clef (that is, the second line from the bottom). The next figure shows a treble clef and the staff position where it assigns the note name G and octave 4.

Figure: A treble clef

A bass clef assigns the note name F and octave 3 on the staff line that passes between the two dots of the bass clef (that is, the second line from the top). The next figure shows a bass clef and the staff position where it assigns the note name F and octave 3.

Figure: A bass clef

By assigning a note name and an octave to a single staff position, we are actually doing so to all the staff positions. Each higher staff position that follows corresponds to the next white piano key on the right. Each lower staff position that follows corresponds to the next white piano key on the left. This is illustrated in the next figure.

Figure: Assigning note names and octaves with the treble clef to staff positions

Grand staff

Music for piano is written in a grand staff. The grand staff is made of two staves connected with a brace. Notes on both the staves are intended to be played together. Usually, an upper staff is intended to be played with the right hand while a lower staff is intended to be played with the left hand. The next figure shows the notes on the grand staff. Below each note, the note name and the octave are written. 

Figure: Note names and octaves in a grand staff

Key signatures

A key signature impacts how the note names are assigned to staff positions. It has either one or more sharps, one or more flats or no sharps/flats at all.

Figure: Examples of key signatures with up to four sharps and flats

Each sharp or flat in the key signature, changes the note name which is assigned to the staff position where the sharp or flat is placed. The important thing is that the note name is changed in all octaves.

The next figure shows a grand staff containing the key signature with three sharps (F#, C# and G#) and how it impacts the note names that are assigned to the staff positions. 

Figure: A key signature and changed note names (marked in red color)

A key signature must be written at the beginning of a staff, after a clef. It is in effect until a change of a key signature is written or the end of a composition. Key signatures will be further explained in chapters Scales and key signatures and Keys and key signatures. 

Accidentals

The two vertical lines in the next figure are called measure lines. Measure lines appear regularly in scores. Measures are delimited with measure lines. In the next figure, the first measure extends from the start until the first measure line, while the second measure extends from the first measure line until the second one. We shall explain measures later. Here, we just mention them so that we can define accidentals properly.

An accidental is a sharp (#), flat (b), double sharp (x), double flat (bb) or natural (♮) that is placed in front of a note. It changes the note name which is assigned to the staff position where it is placed. This change lasts until the end of the measure or the occurrence of another accidental on the same staff position (whichever of these two comes first). Unlike a sharp or flat in a key signature, an accidental impacts only a single staff position.

The next figure shows how accidentals in front of notes impact the note names. The first accidental changes the note name G4 to G#4 until the end of the first measure. The second accidental changes the note name G4 to Gb4 until the occurrence of the third accidental. The third accidental changes the note name Gb4 to G#4 until the end of the second measure. 

Figure: The impact of accidentals on note names (the scopes of impacts are marked in red)

 A natural is used to cancel the impact of a previous accidental or a single sharp or flat from the key signature. The following figure illustrates this. In both cases, the scope of natural’s impact works in the same way as was described above.

Figure: The natural that cancels impact of the previous accidental and the natural that cancels impact of the key signature

It is important to understand that the impact of an accidental on a note name is always the same, no matter which key signature is present. The next figure illustrates this. In the all three key signatures in the figure, the note is the same, it is D#5. In the second key signature, the sharp in front of the note is not required because it is already provided with the key signature. However, it is not wrong to write it again. Sometimes, such redundant accidentals are used as a reminder for the performer.

Figure: In all the key signatures the note is the same, D#5

Enharmonic equivalence

When two different notes have the same pitch, it is called an enharmonic equivalence. For instance, the next figure shows two enharmonically equivalent notes. They have different note names: the first note has the note name F# and the second one has the note name Gb. Thus, they are different. However, they have the same pitch. We can say that the pitch is F#4 or Gb4. Since F#4 and Gb4 are just two different pitch spellings that represent the same pitch. 

Figure: Two notes that are enharmonically equivalent