Marimba and Xylophone

The struck bar to scale (thickness ×2) and its first three bending modes, moving with their live amplitudes, slowed down. The arch cut underneath is what tunes them: 1 : 4 : 10 on the marimba, 1 : 3 on the xylophone. ○ cords at mode 1’s nodes, ▼ mallet, ⌒ tube mouth.

Left: the tube under the struck bar and its air: a quarter wave at the bar’s pitch (largest at the closed bottom, a node at the mouth) and, three times higher, three quarters of one. Right: the energy in bar and tube over the last 4 s, as the tube draws the fundamental out of the bar.

A marimba bar’s partials land on the harmonic grid at 4 and 10 × f₁, a xylophone bar’s at 3 × f₁ (and near 6); a plain bar’s at 2.76 and 5.40 do not.

Wood loses energy fast, and the more so the higher the partial: the upper lines vanish within a tenth of a second and leave the fundamental, which the tube keeps up a little longer. A roll restrikes the bar a dozen times a second.