The column is a 60 cm long tube, preferably transparent (plexi tube from tap plastics or cardboard tube).

Make the tube resonate by holding it next to a speaker and playing this soundfile on your stereo or mp3 player.

Take a small microphone which is connected to your computer or another amplifier and move it up and down inside the column. The microphone picks up the changing Sound Intensity inside the column! You can detect the notes and anti-notes of a standing wave, visualize the sound wave using a recording software such as Audacity, and measure the distance between the nodes.

More details after this coming weekend (12/02).