Jericho: Did the Walls Collapse Due to Resonance?
Joshua 6:14-15, 20 (RSV) And the second day they marched around the city once, and returned into the camp. So they did for six days. On the seventh day It seems possible that the walls of Jericho may have collapsed due to the resonating frequency produced by soldiers marching around it seven times in lockstep.
Source: patheos.com