Beschreibung:
<jats:p>The measurements of the acoustic absorption coefficient were carried out on two kinds of double-layer asphalt located in an urban environment. Three different methods of analysis were used: pseudorandom MLS signal, intensimetry, and Kundt’s tube. The measurements with MLS signal were done with a loudspeaker 3-m high and a 1/2-in. microphone 1.5 m above the asphalt. The absorption coefficient has been obtained by the deconvolution of the MLS signal. In the analysis with the Kundt’s tube, the transfer function method was used on an asphalt core sample (10-cm diameter) extracted ‘‘in situ.’’ Two layers, respectively, 2.5 and 5 cm thick, with different granulometry, composed the first asphalt analyzed. In the second asphalt, the superior layer has a larger granulometry. All the results obtained with the different measurement techniques point out a major absorption peak around 630 Hz and a secondary peak around 2000 Hz, for the first asphalt, and 500 and 4000 Hz for the second asphalt. The measurements point out a large variability of the results obtained in different sections of the road. Variation with asphalt’s composition and measurement uncertainty is analyzed.</jats:p>