- H4-11
- Demonstrates the relationship of pitch and musical intervals to mechanical vibration frequency
- A set of four toothed wheels is mounted on a fast rotator, where the ratio of number of teeth on the four wheels is 4:5:6:8. Tones are produced by holding a piece of cardboard or plastic against the spinning teeth. The resulting notes are the harmonics 4, 5, 6, and 8 of the overtone series, which form a major triad with the octave. A second set of wheels contains a different set of tooth ratios and therefore creates a different (minor) chord.
- H4
