The physics of pitch bending on the vibraphone.

Abstract

The vibraphone is a member of the keyboard (or mallet) percussion family, with tuned aluminum bars typically spanning three chromatic octaves (F3–F6). Extended performance techniques include the use of harmonics and bowing of bars, as well as the pitch bending effect discussed here. After first striking the middle of a bar with a soft mallet in the normal manner, the pitch bend is obtained by pressing a hard mallet onto the bar at a nodal point and then sliding it away from the node as the note sustains. The audible result is a descending pitch, typically of about one semitone. Experimental data on frequency versus location of the hard mallet along the bar are presented. The mass, hardness, and orientation of the sliding mallet relative to the bar are discussed. Interferograms of the lower frequency modes of the bar are also shown. Results are interpreted using a mass perturbation model.