Spectral and Directional Characteristics of Truck Tire Noise

Abstract

The noise from tires predominate over engine/exhaust noise at moderate to high speeds provided the truck is equipped with an adequate muffler and is in a good state of repair. The noise generation characteristics of typical truck tires were measured during an extensive field investigation. The data were frequency analyzed in one-third octave bands and the A-weighted sound level was calculated from these data. Measurement and analysis techniques leading to the acquisition of these data will be discussed. Similarities and differences in the data among the various tread designs and the establishment of data trends associated with changes in speed, load, tread depth, or pavement surface will be discussed. Three-dimensional plots of sound-pressure level versus frequency and time clearly indicating the doppler shift effect will be presented. Equal sound-level contour plots of the data show major lobes to the front and rear of the truck as well as to the side. These spectral and directionality data will supplement existing data on total vehicle noise and serve as a basis for the prediction of noise levels in nearby communities at various distances from present and proposed highways.

Truck noise I-C :

“…These spectral data can be best explained b}" considering the mechanisms by which tire-road interaction noise is generated. As sumirLarized in references [3,17], at present three generic types of tire noise source n.echanisms have been postulatedaerodynamic, air pumping and vibration.…”