Optimizing the exponential sine sweep (ESS) signal for in situ measurements on noise barriers

The measurement of sound reflection and airborne sound insulation of noise barriers in based on the acquisition of impulse responses by means of digital devices. The most widely used methods employ MLS (Maximum Length Sequence) or ESS (Exponential Sine Sweep) as test signals. The theory behind MLS generation and use is well developed and does not involve computational problems. That is why in CEN/TS 1793-5:2003 an MLS signal is recommended. During the European project QUIESST also an ESS signal was applied. The ESS signal has some advantages over MLS, such as a better signal to noise ratio (SNR) and a robust non-linearity rejection. Anyway, the generation of an ESS signal and the subsequent analysis of impulse responses involve some problems whose solutions are not yet common practice. These solutions are discussed here and practical application examples are presented.