Measurement of sound transmission loss by using impedance tubes

The sound transmission loss of several sound absorbent materials was measured by using an impedance tube and was compared with theoretically calculated values. The impedance tube system designed for the testing consisted of an upstream tube, a sample-holder section and a downstream tube. The transfer function method and a four-pole matrix analysis were used in measuring and calculating the sound transmission loss, respectively. Good agreement between the measured and the theoretical values was obtained.