Why do the bars on a xylophone make different sounds?

Related questions

1. Is learning guitar easy?
2. Which language is easier French or Spanish?
3. Is there another name for xylophone?
4. What do you call xylophone sticks?
5. What do you call a xylophone player?
6. How many notes does a xylophone have?
7. How does a xylophone change pitch?
8. Is learning piano easy?
9. What is the range of a xylophone?
10. What's the difference between a xylophone and a glockenspiel?

Tags

1. #other
2. #sound
3. #different
4. #varies
5. #produces
6. #musician
7. #cause
8. #production
9. #often
10. #higher
11. #parallel
12. #orchestra
13. #consists
14. #shorter
15. #xylophone
16. #problems
17. #which
18. #instruments
19. #pitch
20. #xylophones
21. #width
22. #mallet