Membrane Modes
The (4,1) Mode
The seventh mode of a circular membrane is the (4,1) mode which has four nodal diameters and one nodal circle (the outside edge). Like the (1,1), (2,1), (3,1) modes, this pattern is a relatively poor radiator or energy and therefore takes longer to decay, and contributes to the sustained harmonicity and sense of pitch of a timpano. This is the fourth of the preferred modes.
