See: Radiolab’s Walls of Jericho podcast from October 2010.
Act 1: [mp3 | 8M] The hosts lay out the story of Jericho, where an Israelite army brought the walls down, supposedly by shofar (a ram’s horn) blasts. Along the way, we learn about the logarithmic decibel scale. In the final seconds of this clip, we get to the question that all my students were already asking: what would it really take?*
Act 2: [mp3 | 8M] Wherein David Lubman, the acoustical scientist consulted by the hosts, reveals how many shofar blowers it would take to bring down the walls.
Act 3: Continue playing the Act 2 file to explore issues of how to focus the sound and the physics of sound cannons.
*At this point, my kids set to the calculations. They wanted to know if there was a faster way. It was a beautiful experience where the kids asked me to take them from brute-force-arithmetic to honest-to-goddess upper level math. Then I hit play on Act 2. In the words of the experts in this podcast, “there’s a problem.” Just as my class noticed (and demanded we contact the Radiolab folks), another teacher noted a problem in Act 2′s big reveal:
Steven from Palo Alto
There appears to be an inconsistency with the explanation of the mathematics that leads to the total number of shofar players needed to me the 177dB target. If every time the number of shofar players is doubled, the dB level increases by three, then the number of shofar players would have to be doubled 29 times between 95 dB (the sound level of one shofar player) and 177dB. 2^29 shofar players is more than 1000x larger than the 407,380 figure that David Lubman gives. I am not trying to be critical, but I was hoping to use this story as an example of exponential growth for a class that I teach, and this is where my demonstration derails in relation to the podcast. Did anyone look as closely at this part of the story as I did?