Musicians talk about a piece being in a certain key, or jazz musicians may ask which key in which they are about to play a song so they know which notes to play. What does this concept of key mean in music?
Key in Other Contexts
Think about a key in some other contexts. With a lock and key, the key allows you to access something that you could not access before, right? If we say that something is key to our understanding of a broader topic, we mean that we cannot possibly understand the broader topic unless we understand the key concept.
So, a key in other uses of the word is something that opens up closed things or is foundational to understanding. A musical key is just as important. When you understand the key in which a piece is composed, you automatically know the primary notes that the piece will use and the note to which that it wants to flow for resolution.
So, What is Key in Music?
When we refer to a key in music, we generally mean that the following things are clear:
- Tonic Note or Tonal Center: The note to which that melody wants to resolve
- Scale: The pattern of pitches that are used by the piece of music
- Key Signature: When we know the scale and the tonal center, we can determine which notes are flat, natural and sharp, which gives us the key signature of the piece
Tonic Note or Tonal Center
The tonic note, or tonal center is simply the note that the piece seems to start from and wants to resolve to throughout the piece. When a musician says “this piece is in G”, they are saying that G is the tonic note. When you see a title such as “Symphony in Bb”, then Bb is the tonic note of the overall work.
While the tonic note gives us some information about the key, there are many patterns of notes that could be used that have the same tonic note. The scale that a piece is based on fills in the missing details.
A scale is simply a series of notes that follow a regular pattern of intervals. In Western music the two most common scales are the major scale and minor scale. Though they are the most common, there are other options as well, including Dorian, Lydian, whole tone, chromatic and diminished. For now, let’s focus on major and minor – in fact, we will start with just major!
A major scale forms a specific pattern of ascending whole and half steps as follows:
Whole Whole Half Whole Whole Whole Half
This means that if I know the starting note, or tonic note, I can use the pattern to figure out all of the other notes of the scale. Remember, when the pattern moves a half step, go to the adjacent key on the keyboard; when the pattern moves a whole step, skip one key on the keyboard.
So, if our tonic note is G and we want to find the notes of the G major scale, we can do the following:
- Start on G
- Whole Step: Skip G#/Ab to land on A
- Whole Step: Skip A#/Bb to land on B
- Half Step: Move to the next key, which is C
- Whole Step: Skip C#/Db to land on D
- Whole Step: Skip D#/Eb to land on E
- Whole Step: Skip F to land on F#
- Half Step: Move to the next key, which is G (completing the scale)
Written in musical notation using accidentals, the G Major Scale looks like this:
We can also write the G Major Scale in musical notation using the key signature with one sharp (F#):