二胡的有效弦长多因人而异;琴马的安放位置根据音响而定,一般设在琴筒前口中部偏上一点;琴弓擦弦点在琴筒皮膜护片以上,运弓时弓毛与膜面近于垂直。这是目前的状况,人们也习以为常。但从弦振动的原理及二胡发音的谐和性来看,对此仍有探讨一下的必要。琴弦的整体振动产生基音,分段振动(全长的1/2、1/3、1/4……)产生泛音。把擦弦点设于有效弦长的七分之一及九分之一处,可以削弱或消除不谐和的第七或第九泛音。 Erhu effective chord length varies from person to person; placement of the pianoforte according to the sound may be, generally located in the middle of the front part of the piano bow slightly above the point; Hair and membrane near vertical. This is the current situation and people are used to it. However, from the principle of string vibration and erhu pronunciation of harmony, this is still necessary to explore. The whole vibration of the string produces the pitch, and the segmented vibration (1/2, 1/3, 1/4, ... of full length) produces overtones. Setting the point at one-seventh and one-ninth of the effective chord length weakens or eliminates the dissonant seventh or ninth harmonic.