What is Sound?

Vibration Creates Form

Ernst Chladni (1756–1827) was a German physicist and musician.

His important works include research on vibrating plates and the calculation of the speed of sound for different gases. For this some call him the "Father of Acoustics". Chladni's technique, first published in 1787 his book, Entdeckungen über die Theorie des Klanges ("Discoveries in the Theory of Sound"), consists of drawing a bow over a piece of metal whose surface is lightly covered with sand. The plate is bowed until it reaches resonance and the sand forms a pattern showing the nodal regions.

The following is a drawing from Chladni's original publication.

He illustrated it with diagrams of the vibrations of thin metal plates.














Chladni Figures and Vibrating Plates
An applet that demonstrates the mode patterns of vibrating circular and rectangular plates :
http://www.phy.davidson.edu/StuHome/jimn/Java/modes.html