Membrane Modes

The (3,1) Mode
The fifth mode of a circular membrane is the (3,1) mode which has three nodal diameters and one nodal circle (the outside edge). Like the (1,1) and (2,1) modes, this pattern is a poor radiator of energy and therefore takes longer to decay, and contributes to the harmonicity of the pitch of a timpano. It is the third of the preferred modes.