Abstract:

Experimental determination of the natural frequencies and nodal line patterns of those modes which produce sound was made of a test violin which had previously been analyzed by George Bissinger using an experimental modal analysis system [J. Acoust. Soc. Am. 97, 3154--3164 (1995)]. Excitation of the test violin was done by bowing the instrument and the analysis system was the CONQT software previously used by the author. Nodal lines were defined approximately with a small microphone which was held very closely to the plate surface to seek lines of minimum response. Comparison with the Bissinger results points out the very few vibration modes in the first 1000 Hz which contribute to the overall tone of the instrument. These modes are found among those displayed in Bissinger's work. Only two modes of the air cavity and four modes of the gross mechanical system are important in this frequency range. The CONQT data suggest that tone quality is determined strongly by the five to seven prominent higher modes, which are complex motions of small areas of the plates, and/or by the ability of the lower modes to transmit sound at off-peak frequencies.