noise-reduction coefficient

例句：

1. 1.The noise reduction coefficient of the new air filter is 40 dB.
   新型空气过滤器的降噪系数为40分贝。
2. 2.The noise reduction coefficient is a key factor in determining the effectiveness of a soundproofing system.
   降噪系数是决定隔音系统有效性的关键因素。
3. 3. The noise reduction coefficient is calculated based on the acoustic impedance of the materials used in the soundproofing system.
   降噪系数是根据隔音系统中使用材料声学阻抗计算得出的。