Experimental study of vibraphone pitch bending using electronic speckle-pattern interferometry.

Abstract

Pitch bending on the vibraphone is an extended performance technique called for by modern composers dating back to the 1960s. 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 showing frequency vs location of the hard mallet al.ong the bar are presented and interpreted with the use of time-averaged electronic speckle-pattern interferograms showing the vibrational modes of the vibraphone bar. Frequency vs mallet mass data are also presented and discussed. In addition, it is shown that for some combinations of mallet type and vibrational mode this technique can produce an increase in frequency.