按下按钮，以减少喇叭的音量。

Press the Down button to decrease the Speaker Volume.

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此外，通过降低天花板的高度，木材的长度被缩短，也减少了空调的音量。

Moreover, by lowering the ceiling height, timber length was shortened and air-conditioning volume was also reduced.

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如果在噪音源处减少噪音量行不通或不够要求，可以采用吸收或限制噪音的办法。

Where reducing the noise output at the source is impractical or insufficient, noise may be absorbed or confined.

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