L. f. noise can be better attenuated so as to obtain good attenuation characteristics over the entire audible frequency range by using active noise reduction technique in the closed-air type earmuff.
在密闭型耳罩中，利用有源降噪技术可以较好地衰减低频噪声以使整个可听声频率范围内获得良好的衰减特性。
2
We analyze the theory of attenuated total reflection (ATR) and find the coupling method to excite the SPR and introduce the coupling type of the SPR sensor.