Point of absolute rest in a vibrating string we call a node.

一条绳子上绝对震动静止的点,我们称之为节点。

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The string is vibrating higher when it's exactly twice what the lower one is.

高音弦的震动频率,正好是低音弦的两倍

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That's the harmonic series that's on that, and what the valves do is they shorten and lengthen that vibrating column of air very much like the cello string on the fingerboard.

这就是圆号上的泛音列,活瓣的作用是增长或减短,空气柱的高度,很像大提琴指板上的弦

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