Across
- 6. superposition
- 9. moving
- 12. maximum
- 13. drum
- 16. no-travel
- 18. motion
- 20. together
Down
- 1. continuousness
- 2. cancellation
- 3. reinforcement
- 4. overtones
- 5. interference
- 7. echo
- 8. high-speed
- 10. low-sound
- 11. apart
- 14. sound-unit
- 15. rapid
- 17. tone
- 19. zero-displacement
- 21. ratio