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Across 4. This wave has backwards to forwards movments 5. Sounds above the range of human hearing are called 7. The effect when waves bend round the sides of an obstacle 11. This measure the amount of depth under a boat 12. The speed of sound done not depend on this 14. Musical scales are measured in these 15. This graph shows how the air pressure in a microphone varies 16. The propertines of waves can be studied using 17. The speed of sound goes faster through this 18. Frequency is measured in these

Down 1. Sound waves are caused by these 2. When a series of compressions travel through the air its called 3. A surveyor can use this to measure the distance between 2 walls 6. This wave has side to side movments 8. Wavelengths are measured in these 9. Sound cannot travel through this 10. The number of oscillations per second is called 11. When sound waves refelct from a wall you hear this 13. Sound waves travel faster through this type of air 16. This can be used to detect the postions of aircrafts by measuring echo times