This experiment investigates standing sound waves in a tube subject to different boundary conditions. One end of the tube is closed off with a small speaker, while the other end is closed with a movable piston which can be used to change the length of the tube. Sinusoidal sound waves are produced by the speaker and detected by a small microphone in the tube. At resonant frequencies of the tube, the sound waves will have maximum amplitude and students will measure the wavelength of the sound for the different standing waves. In a second experiment, a pulse of sound is sent down the tube and then the reflected pulse is examined under different boundary conditions.