Acoustical effect of progressive undercutting of percussive aluminum bars Free

Standard vibraphone bars consist of aluminum beams which are traditionally tuned with an arched undercut, for the purpose of aligning the musical overtones harmonically. The acoustical effect of various progressions of undercuts on aluminum bars was studied using both an aluminum bar and a finite element computer model. The spectral signature of the aluminum bar was examined with a spectrum analyzer, and the corresponding eigenmodes were imaged with an electronic speckle pattern interferometer. These methods were used to analyze the changes in natural frequencies of the bar as matter was removed from various locations. Additionally, the aural character of each cut was captured with an audio recording, and the fundamental tone was normalized over all recordings to make possible a subjective comparison of the timbral differences of differently cut bars.