The simplest way to dampen a helicopter's noise is to increase the Angle of the rotor's blades, also called the pitch, and slow them down.

要降低噪音，最简单的方法是增大旋翼桨叶的夹角，也叫“节距”，或是降低转速。

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The main blades pitch Angle is controlled by the up and down movements of the swashplate.

大桨的螺距角度是由倾斜盘的上升和下降动作控制的。

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