Citations
For information:
Page 2: https://www.physicsclassroom.com/class/sound/Lesson-1/Sound-is-a-Pressure-Wave
page 3:https://www.livescience.com/37734-how-far-away-is-lightning-distance.html
page 3: https://askabiologist.asu.edu/echolocation
page 4: https://electronics.howstuffworks.com/speaker1.htm
page 5: https://www.nidcd.nih.gov/health/hearing-aids