In-situ measurements of sound reflection and sound insulation of noise barriers: validation by means of signal-to-noise ratio calculations

After some years from the its release, the CEN/TS 1793-5 European standard for in-situ measurement of sound reflection and airborne sound insulation characteristics of noise barriers has been significantly enhanced and validated in the frame of the EU funded QUIESST project. The procedure, based on impulse response measurements near the noise barrier and in the free field, is robust and easily applicable but much attention must be paid when: i) applying the signal subtraction technique to get the reflected signal component and ii) extracting the transmitted component, especially measuring highly insulating noise barriers. In both cases, it is essential to avoid a poor signal-to-noise ratio of the critical part of the impulse response. In the frame of the QUIESST project specific quality criteria, applicable on site, have been introduced in order to check and validate the result. These criteria are rigorously described here for the first time and illustrative examples are presented.