I'm in highschool so I'm looking for a highschool-level lab idea.
One other interesting way to do this would be to set up standing waves in water and measuring the total number and location of nodes to find which mode the waves are in.And since we are driving the waves we know the driving frequency,with this information we can find speed of sound.
In the oil business one would place a source at a known distance from a geophone -a receiver, fire the source and record the time, and record the time the wavelet arrived at the phone. A source could be anything that would supply a short rap. Many smart phones contain accelerometer sensors that can be used as a receiver I'm thinking of putting smart phones on either outside ends of a container of water and sharply rapping an object as a source. Water is around 5000 ft/second or 1500 m/sec so I'm worried about the time resolution on the phones, assuming they record time for an event.