Sound insulation measurements on noise barriers across their entire extension: a preliminary study

EN 1793-6 allows measuring the in-situ sound insulation of installed noise barriers at selected positions, but it would be desirable to check the quality of the installation or the decrease in performance over time of a whole long barrier. For this purpose it is necessary to carry out measurements along the entire extension of the noise barrier and not just at few single positions taken as representative. This work presents a preliminary study of a quick method for evaluating airborne sound insulation along the entire length of a noise barrier and finding weak points, like assembly errors. Preliminary measurements were made by moving an array of microphones mounted on a vertical rod along the entire width of the barrier, in 0.25 m steps. On the opposite side of the barrier (noise source side) a loudspeaker was held in axis with the microphones, at fixed height, for each step. The entire surface of a 9 m wide, 4 m high sample barrier was analysed. Processing the measured impulse responses between the loudspeaker and the microphones, global images of the local airborne sound insulation can be obtained in each frequency band.