对两种吸声系数测量方法的讨论

某黑色聚氨酯材料样本放置于自行设计的管道脉冲吸声测量装置的管道中间以及管道末端并紧贴刚性背衬两种情况下，利用产生的1ms的巴特沃斯函数声脉冲测量其吸声系数。样本放于声管末端的反射法测量结果与B＆K4206阻抗管测量结果相近；而放于声管中间的透射法测量结果与反射法有区别。从声能量角度解算了两种测量的平均吸声系数表明：相比于单层样品，双层样品的透射法测量结果与反射法更接近。

Discussion of Two Methods for Sound Absorption Coefficient Measurement

Using the self-designed system for sound impulse absorption measurement, a series of Butterworth sound impulse with 1 ms duration is generated in the sound pipelines. The sound absorption coefficients of a black polyurethane foam sample is measured in two situations ： （ 1 ） the sample is placed in the middle of the pipeline and （2） the sample is placed at the end of the pipeline and clung on to the rigid cover. It is found that the measurement result with the reflection method is close to that with B＆K 4206 impedance tube measurement for situation （2）, while results from the two measurement methods are somewhat different for situation （ 1 ）. In addition, the averages of sound absorption coefficients for the two methods are resolved and discussed from the acoustic energy viewpoint. As a result, compared with the single-layer sample, sound absorption coefficient measured by the transmission method for double-layer sample is more close to that measured by the reflection method.