具有非线性边界条件的琴弦振动：京胡“开花音”的声学研究

String vibration with nonlinear boundary condition:an acoustical study of "blossoming tones" produced by the junhu

京胡的开花音是一种能变化音色、渲染情绪的特殊声响,演奏方法是让左手手指轻触琴弦,右手用力拉出音头,由于左手手指与琴弦之间仅有微小的距离,琴弦振动时会不断碰撞指头,因此能产生丰富的噪音。开花音主要由高通噪音所构成,其截止频率约为1.7kHz。演奏开花音时,琴弦接触手指的时间间隔长短不定,但通常短于0.5毫秒,此测量值与其截止频率大致吻合。

Blossoming tones of the jinhu are produced with a special touch technique of the left hand, and a chaotic behavior of string vibration arises from a nonlinear boundary condition with unilateral constraints. The spectra of blossoming tones mainly comprise high-pass noises, with the cutoff frequency of approximately 1.7 kHz.