Acoustic radiation from bowed violins

Abstract

Near-field acoustic holography ͑NAH͒ is applied to visualize the acoustic radiation from bowed violins across a frequency range from 294 Hz to 3 kHz. These visualizations are employed to localize regions of acoustic radiation from surfaces of violins. Three violins were tested: a common student instrument by Scherl and Roth; Hutchins violin SUS295, which has been the subject of many previous investigations; and a Hutchins mezzo violin from the Violin Octet set of instruments, which is longer, broader, and thinner than a standard instrument. The violins were bowed continuously with an open-frame mechanical bowing machine, while NAH measurements were made on four planes surrounding the instrument. Mappings of the acoustic intensity are presented that show locations of maximum radiation at low and high frequencies with a spatial resolution smaller than the acoustic wavelength. Comparisons are made of the radiation patterns between the two conventional instruments and the mezzo violin. Radiation patterns from SUS295 at frequencies near to known modal responses are also presented.

Sound radiation from Caribbean steelpans using nearfield acoustical holography

“…All of the published material has been generated by Copeland and Muddeen. 2 A pertinent, documented application of NAH specifically to a musical instrument is to be found in Wang 6 and Wang and Burroughs. 7 These documents examined the acoustic radiation from bowed violins using NAH.…”

Non-impulsive signal deconvolution for computation of violin impulse responses

“…Reciprocal methods use excitation of the sound field with a known volume and measuring the velocity of the bridge to calculate the impulse response of the body, but it is mentioned that the reciprocal methods yield inferior results than the direct ones. In [8], it is mentioned that for violin sound radiation, a steadystate bowing method is favored because it is closer to human performance; although the focus of that study was not violin body modelling, it helps raise the question that other methods could be developed to obtain the transfer function between the body excitation and its radiated sound.…”

Beamforming with microphone arrays for directional sources

“…For example, in [Wang 2001] multiplanar NAH is used "[...] to characterize the radiated sound field when the violin is played at frequencies extending from 294 Hz Christian Bouchard Ph.D. Thesis to 3 kHz, and more specifically, to localize the regions on the violin structure from which significant sound energy originates". Not much detail is provided for the far-field directivity pattern other than saying that at low frequencies the far-field radiation is omnidirectional, and that around 880 Hz the far-field pattern is cardioid.…”