The role of acoustic tube resonances in the radiation of sound from circumferentially ribbed truck tires

Abstract

While in contact with the pavement surface, the grooves of circumferentially ribbed tires form tubes open at both the leading and trailing edges of the tire contact patch. These tubes efficiently radiale sound at the fundamental resonant frequency, corresponding to an acoustic wavelength equal to one half of the tube length, and at the higher harmonic frequencies. This behavior was studied with acoustic intensity measurements made alongside a moving straight rib (HCR) truck tire using the technique described in a previous presentation [L. J. Oswald and P. R. Donavan, J. Acoust. Soc. Am. Suppl. 1, 67, S71 (1980)]. These data show a 3 to 7 dB reduction from 500 to 2500 Hz in the narrow-band acoustic intensity spectrum when the resonant-tube radiation is eliminated with open cell foam placed in the grooves. Further, consistent with the dipolelike radiation from the tube ends occurring at the odd-numbered tube harmonics, distinct nulls in the acoustic intensity were measured alongside the center of the contact patch at these frequencies. The influence of resonant tube radiation is also discussed for commercial wavy rib truck and passenger car tires.