Elementary stability considerations for bowed‐string motion
作者:
Gabriel Weinreich,
René Caussé,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1991)
卷期:
Volume 89,
issue 2
页码: 887-895
ISSN:0001-4966
年代: 1991
DOI:10.1121/1.1894650
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Using the approach first pioneered by Raman, the Helmholtz motion of a bowed string is discussed as a special case of “two‐velocity motions,” in which a given point (at which the bow is located) alternates, in the course of a cycle, between two constant velocities. The fact that the bow typically presents a negative resistance to the string during the “slipping” part of the cycle is adduced as a reason for the “duty cycle,” that is, the fraction of the period that corresponds to slipping, to try to become as short as possible. It is shown that, for a string without dissipation or stiffness, this duty cycle can be arbitrarily low for general bow positions; data obtained with the “digital bow” illustrate this behavior. It is shown theoretically, and confirmed with computer simulations, that instabilities arising from the negative slipping resistance cannot be eliminated by assigning a finite positive value to the sticking resistance. The apparent stability of Helmholtz motion observed in real playing situations remains a puzzle.
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