The bodhrán is a particular drum used in Irish traditional music. The video below shows a little experiment I did to illustrate my internship in Marseille. More visual than musical…
A membrane (drum), on which small particles (black sand) are placed, resonates according to some notes made with a guitar. For certain particular frequencies (eigenfrequencies), clearly visible shapes appear: the sand settles where the membrane is stationary, forming nodal lines. Each eigenfrequency corresponds to a certain shape, whose complexity tends to increase with the frequency value.