Playing fire from your speaker...

Have you ever wondered what a sound waves look like? Apparently, there is this thing called a Rubens' Tube that will allow a visual representation. In 1904, Heinrich Rubens sealed a tube on both ends, drilled a series of equidistant holes along one side of the tube and allowed gas to enter from the side one of the seals. This tube allows for a visual representation of sound when the gas comes out of the drilled holes is lit and sound is made from one side of the tube. It works so well that someone using this device could easily measure the length of a sound wave when kept at a constant pitch. Here is a link to a video of the device.