Sound & Echo Crossword

1234567
Across
  1. 3. Material (solid, liquid, gas) through which sound travels.
  2. 4. Sound travels fastest through this type of matter.
  3. 5. Sound that is reflected back to the listener.
  4. 6. Back and forth movement of an object that produces sound.
Down
  1. 1. Uses echo sounding to measure the depth of the sea.
  2. 2. To bounce back (used for sound waves).
  3. 4. Energy of vibration we can hear.
  4. 7. Animal that uses echoes to navigate and find food.