The Semitone
In Western music, the smallest interval is the semitone (the distance between any two adjacent keys on a piano). There are 12 semitones in an octave.
Cents (The Micro-Unit)
Sometimes a note is slightly sharp or flat. We use Cents to measure this.
- 100 Cents = 1 Semitone
- 1,200 Cents = 1 Octave
Equal Temperament
Modern pianos are tuned using "Equal Temperament," where every semitone is exactly 100 cents. Historically, people used "Just Intonation," which used pure mathematical ratios (like 3:2 for a perfect fifth).
Key Takeaways
- Cents allow for "micro-tuning"
- The "A440" standard means the note A vibrates at 440 Hz
- Frequency doubles with every octave