Scene
Galton board
300 balls fall through 12 rows of pegs into 13 bins. Each bin plays its own note, so as the bins fill up you can hear the bell curve take shape.
Make this videoWhat happens
At every peg a ball goes left or right with equal chance. After 12 rows, the bin it lands in is simply the number of times it went right. That gives a binomial distribution: the middle bin collects about 23% of the balls and the outer bins almost none. A new ball drops every 0.08 seconds, so all 300 are down in under half a minute.
| Bin | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Variation 14 | 0 | 1 | 6 | 17 | 31 | 58 | 60 | 67 | 36 | 20 | 3 | 0 | 1 |
| Expected | 0 | 1 | 5 | 16 | 36 | 58 | 68 | 58 | 36 | 16 | 5 | 1 | 0 |
Variation 14 even put a ball in an end bin, a path with odds of 1 in 4,096 for a single ball. With 300 balls, at least one lands in either end bin in roughly 1 run out of 7.
What you hear
Each landing plays the note for its bin, low on the left and high on the right, using a D major pentatonic scale. Most balls land in the middle, so the middle notes repeat most and the sound settles toward the center as the curve fills. Every peg hit adds a quiet tick, which turns into a soft rain once dozens of balls are falling at once.
Songs that fit
The bins take the first 13 notes of whatever melody you pick, left to right. A scale sounds the most natural because neighbouring bins get neighbouring notes. With a tune like Für Elise the board plays fragments of it in a scrambled order, which can sound good too, just less tidy.
Make your own
Open Galton board in the maker, pick a song or upload a MIDI file, and download the MP4. Variation 14 is the one in the preview above. The same variation number always gives the same video, so you can share a link and get identical results.
Other scenes
- Spinning hexagon: The spinning hexagon test with a gap in one wall. The spin speeds up with every bounce.
- Escape the rings: A ball bounces inside 22 spinning rings. Each ring has a gap, and the ring breaks once the ball gets through it.
- Growing ball: The ball gets a little bigger on every bounce until it fills the circle.
- Every bounce adds a ball: Every bounce can add another ball, up to 200 of them, while a slowly widening gap lets them out.
- Shrinking ring: The ring gets 1.5% smaller every time it is hit, until the ball no longer fits.
- 100 strings: Each hit ties a string to the ring and speeds the ball up. The ring has to hold 100 of them.
- Color war: Two balls paint the ring in their own colour. Whoever owns more of it after 30 seconds wins.
- Ball race: Four balls, one small spinning exit. First one out wins.