THE GENERATION OF TYRE/ROAD NOISE

Roadside noise data, collected under typical Australian conditions using the passby technique, are presented for varying road surface macrotexture, tyre tread pattern and vehicle speed. A simple mathematical model describing the variations in measured noise levels as a function of these three parameters is derived and evaluated. This model is found to perform reasonably well for unweighted noise levels, poorly as expected for the a-weighted levels and to be limited by some underlying assumptions. Using frequency spectral analysis techniques the various sources of vehicle roadside noise are identified and their behaviour observed. These sources, particularly tyre and road, are shown to interact in a complex manner to generate the total roadside noise. Analysis of these spectra show that the tyre and road components of roadside noise occur primarily over different frequency ranges. As road surface macrotexture increases in coarseness, the measured road components of roadside noise are seen to increase in level while the tyre components are seen to decrease. Measured frequency spectra are found to vary most over those frequency regions associated with road surface macrotexture. An advanced theoretical model, based on air pumping tyre/ road noise generation is also derived and evaluated. This model is shown to predict reasonably well both the magnitudes and fluctuations of the tyre related noise components measured for a particular experimental tyre. It does, therefore, advance understanding of the tyre/ road noise generation process. The report concludes with some applications to low noise road and tyre design and to traffic noise prediction (a). The isbn of the microfiche version is 0 86910 062 9.