Research in Musical Acoustics

My research ties together my experiences as a musician with my training in optics. I focus on vibrational studies of percussion instruments, with an emphasis on studies of how the natural frequencies and mode shapes of the instruments change in response to musically relevant perturbations.

Electronic Speckle Pattern Interferometry

In electronic speckle pattern interferometry (ESPI), light from a laser is split into two beams, with one beam reflecting off the vibrating object being studied. The other beam serves as a reference, and is not changed by vibrations of the object.  When these two beams of light are recombined they form an interference pattern that can be recorded with a CCD camera.  With appropriate processing of these images the vibrational patterns of the object can be captured. 

The ESPI system is constructed from discrete optical components on a vibration isolation table.  In the resulting images nodal lines appear white.  Gray levels correspond to contours of equal amplitude motion. Each vibrational mode corresponds to a particular frequency of vibration.

Finite Element Analysis

Finite elelment analysis (FEA) software is used to create computer models of the object being studied. The model can be used to calculate the frequencies and mode shapes of the object for comparison with the experimental ESPI results.

Recent Publications

"Musical Acoustics of Orchestral Water Crotales," Journal of the Acoustical Society of America 131, 935-944, January 2012.

"Normal Modes of a Musical Drumhead under Non-uniform Tension," Journal of the Acoustical Society of America 127, 525-533, January 2010.

"Drum Tuning: An Experimental Analysis of Membrane Modes Under Slightly Non-uniform Tension," Acoustical Society of America, Proceedings of Meetings on Acoustics, 5, 035001, 2009.

Recent Presentations

"Experimental Study of Vibraphone Pitch Bending using Electronic Speckle-Pattern Interferometry," Acoustical Society of America, 161st Meeting, Seattle, May 2011 (Invited).

"Musical Acoustics of Water Crotales," ViennaTalk 2010 on Musical Acoustics, Vienna, September 2010 (Invited).

"The Physics of Pitch Bending on the Vibraphone," Acoustical Society of America 159th Meeting, Baltimore, April 2010.

"Physics of Water Crotales," Acoustical Society of America 158th Meeting, San Antonio, October 2009.

"Normal Modes of a Circular Drumhead Under Non-uniform Tension: Mode Splitting with Respect to Perturbation Symmetry," Acoustical Society of America 157th Meeting, Portland, May 2009.

"Drum Tuning: An Experimental Analysis of Membrane Modes Under Slightly Non-uniform Tension," Acoustical Society of America 156th Meeting, Miami, November 2008.