Working out the key of a song played on the piano generally involves identifying the tonal center and the mode (major or minor) of the music. Here's a breakdown of how to do it:
1. Identifying the Tonal Center (The "Key")
The tonal center, often just called the "key," is the note around which the melody and harmony revolve. Here's how to find it:
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Listen for the "Home" Note: Pay attention to which note sounds like the resolution or the most stable point in the music. This is often the last note of the song or a recurring note in the melody.
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Analyze the Chords: Identify the chords being used. The most important chord is usually the tonic chord (the chord built on the "home" note). Common chord progressions often resolve back to the tonic chord.
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Look for Accidentals: Notice any sharps (#) or flats (b) consistently used throughout the song. These accidentals often indicate the key signature.
2. Determining Major or Minor
Once you've identified the tonal center, you need to determine whether the song is in a major or minor key:
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Listen to the Overall Mood: Major keys generally sound bright, happy, and uplifting, while minor keys tend to sound darker, sadder, or more introspective.
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Analyze the Tonic Chord: Is the tonic chord major or minor? A major tonic chord strongly suggests a major key. A minor tonic chord suggests a minor key.
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Analyze the Intervals: Compare the intervals within the melody and harmony to the characteristic intervals of major and minor scales.
3. Using Scale Formulas (For Major Keys)
If you suspect the song is in a major key:
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Major Scale Formula: Major keys follow the major scale formula: Whole-Whole-Half-Whole-Whole-Whole-Half (or 2-2-1-2-2-2-1, where 2 represents a whole step and 1 represents a half step).
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Starting Note: Begin on the note you believe is the key (the tonal center).
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Apply the Formula: Count forward on the piano keyboard using the whole and half step intervals to create the major scale. For example, if you suspect the key is C major, start on C. C to D is a whole step, D to E is a whole step, E to F is a half step, F to G is a whole step, G to A is a whole step, A to B is a whole step, and B to C is a half step.
4. Understanding Key Signatures
Key signatures (the sharps or flats at the beginning of a musical staff) can give you clues:
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Major Keys and Sharps:
- 1 sharp: G major
- 2 sharps: D major
- 3 sharps: A major
- 4 sharps: E major
- 5 sharps: B major
- 6 sharps: F# major
- 7 sharps: C# major
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Major Keys and Flats:
- 1 flat: F major
- 2 flats: Bb major
- 3 flats: Eb major
- 4 flats: Ab major
- 5 flats: Db major
- 6 flats: Gb major
- 7 flats: Cb major
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Relative Minor: Every major key has a relative minor key that shares the same key signature. To find the relative minor, count down three half steps from the major key's tonic. For example, the relative minor of C major is A minor.
Example
Let's say you're trying to determine the key of a simple song. You notice the song seems to resolve to a C note, and the overall mood is bright. You suspect it's C major.
- Tonal Center: C
- Mood: Bright (suggesting major)
- Key Signature: No sharps or flats, which aligns with C major.
- Scale Formula: Start on C and apply the major scale formula (2-2-1-2-2-2-1): C-D-E-F-G-A-B-C. This confirms that the song is likely in C major.
By combining these methods, you can effectively work out the key of a song played on the piano.
