New method of measuring input admittance of stringed instruments
Gabriel Weinreich, Levon L. Yoder · The Journal of the Acoustical Society of America · 1987
When a stringed instrument, such as a violin, is subjected to an applied time-harmonic force and the resulting velocity of the bridge is measured, the quantity usually referred to as the “input admittance” in fact functions as an output admittance. Its value can be inferred by loading the bridge with a known external impedance and comparing the velocities with and without this loading. In our experiment, the external loading impedance is a known mass, and the applied force results from an irradiating acoustic field. By taking data with two different field configurations, we can independently determine the four elements of the two-dimensional input admittance matrix referred to the two possible polarization directions of the string vibration. We utilize the digital data acquisition and processing system that has been previously developed for radiativity measurements, in which an appropriate broadband stimulating signal allows a large spectrum of data to be obtained in a few seconds. Some results will be shown. [Work supported by NSF.]