What is Sound?  Flame Challenge:  Vibrations and Vocal Chords
Channel: Janet Coonce
Date: 17/04/2016

WARNING:  Close your eyes at 3:38 if you do not wish to see what real vocal chords look like while singing and laughing.   This video was designed to help you understand, "What is Sound?" (as part of Alan Alda's challenge to explain sound to a 5th grader).

At the end of the video, you SEE the LIGHT from the fireworks. Then, you HEAR the SOUNDS of the fireworks. This is because the speed of sound through cold air is nearly a million times SLOWER than the speed of LIGHT. When we talk about the speed of sound, we're talking about how fast sound travels over a certain distance, like a mile or a kilometer. The actual speed of sound depends on the MATTER that it's going through.   DISCUSSION QUESTIONS: Through air, sound travels about 1 mile every 5 seconds, or about 340 meters every 1 second. (1) If you see a firework, and then hear the pop 2 seconds later, approximately how many meters away were you from the firework's blast? (2) If you see a flash of lighting, and then hear the thunder 15 seconds later, approximately how many miles away was the lighting strike from your ear? 

ACTIVITY#1:  Measure the speed of sound by following the directions at this webpage:   http://www.instructables.com/id/How-to-measure-the-speed-of-sound-with-two-lumps-o/    Do you think the speed of sound is faster through hot air or through cold air? Through water (a liquid) or air (a gas)? How could you design experiments to test your predictions?

ACTIVITY#2:
What do you hear when a sound wave's AMPLITUDE is increased?Explore on your own: http://phet.colorado.edu/en/simulations/category/physics/sound-and-waves 
PhET Interactive Simulations, University of Colorado Boulder, phet.colorado.edu

ACTIVITY#3:
Use cardboard boxes and rubber bands of different sizes and thicknesses to create a musical instrument.   Are higher frequency sounds generated by thinner or thicker rubber bands? Experiment by "plucking" different rubber band lengths, thicknesses, and tensions.  Record your observations. Create a model of vocal chords of (a) a baby, (b) a soprano-singing adult woman, and (c) an bass-singing adult man. 

I hope this video helped you become a little more knowledgeable AND curious about sound.  :-)    This video was co-created by Tennesee Tech University Chemistry Instructor Janet Gray Coonce and Tennessee Tech University graduate student Haley Snyder Curtis, with acting help from Mrs. Coonce's family. Special thanks to the TTU STEM Lending library for equipment access, Dr. Grant Rohman for the vocal chord examination, and the two anonymous TTU music students who sang the "High Frequency"/ "Low Frequency" tune. Questions? Contact Janet Gray Coonce at jcoonce@tntech.edu.