传统的测量吸声系数的方法主要有混响室法和驻波管法，这类方法易受实验条件限制，在实际工程中的应用有一定的局限性。本文中使用四传声器，基于所测量的三维声强的矢量特性，通过前后两次分别测量被测试件和全反射板反射的声强幅值来计算相应的吸声系数大小，提出了一种新的测量斜入射吸声系数的方法; 该方法在测量材料吸声系数的同时，还可以测出声波的入射角和反射角。首先进行了三维声强法测量吸声系数的原理分析; 然后利用软件对该系统进行数值仿真，探讨了不同频段、不同吸声系数和不同入射角下吸声系数的测量误差; 最后，利用该方法对 3 种材料进行实验测量，将结果与驻波管法测量得到的结果进行对比，并检验其方向性误差。结果表明: 该方法在 630 ～4000Hz 频段内测得的吸声系数与驻波管法测得的吸声系数的误差在 ±0. 02 ～±0. 10 间，方向性误差在 1° ～6°之间; 从 0°到 80°的不同入射角下方向性误差在 1° ～3. 5°之间。

Reverberation chamber method and the standing wave tube method are two main traditional methods to measure the sound absorption coefficient． But they are easy to be limited by experimental conditions and have some limitations in practical engineering applications． Based on the vector characteristics of the measured three-dimen-sional sound intensity，a four-microphone was used to calculate the corresponding sound absorption coefficient by measuring the amplitude of the sound intensity reflected by the tested specimen and the total reflector plate，re-spectively． This method can not only measure the absorption coefficient of materials，but also measure the inci-dence angle and reflection angle of sound waves． Firstly，the principle analysis of the measurement of the sound absorption coefficient was carried out by the three-dimensional sound intensity method． Then the software was used to simulate the system，and the measurement errors of the absorption coefficient in different frequency band，diffe-rent absorption coefficient and different incidence angle were discussed． At last，the method was used to measure the three materials，and the results were compared with the results of standing wave tube method，and the directivi-ty error was tested． The results show that the error range of the absorption coefficients of 630 ～ 4 000Hz measured
by this method and the standing wave tube method is ± 0. 02 ～ ±0. 10，the directivity error is between 1 ° and 6 °，and the directivity error of different incident angles from 0 ° to 80 ° is between 1 ° and 3. 5 °．