Each piano plays two notes of the same interval at the touch of a single key.
| interval | technical name |
|---|---|
| 1 semitone | minor second |
| 2 semitones | major second |
| 3 semitones | minor third |
| 4 semitones | major third |
| 5 semitones | perfect fourth |
| 6 semitones | tritone |
| 7 semitones | perfect fifth |
| 8 semitones | minor sixth |
| 9 semitones | major sixth |
| 10 semitones | minor seventh |
| 11 semitones | major seventh |
| 12 semitones | octave |