Wind noise influence on close-proximity tyre/road noise measurements with uncovered systems
ANFOSSO LEDEE ; KRAGH
Type de document
COMMUNICATION AVEC ACTES INTERNATIONAL (ACTI)
Langue
anglais
Auteur
ANFOSSO LEDEE ; KRAGH
Résumé / Abstract
When measuring tyre/road noise by the Close-ProXimity (CPX) method, microphones are fitted close to a test tyre mounted on a trailer or self-propelled vehicle, and the system is driven at speeds up to 110 km/h. When the trailer is covered by an enclosure, wind noise in the microphones is believed to be reduced. However, for uncovered systems, wind noise may contaminate tyre/road noise measurements. Wind induced noise was measured for two types of uncovered equipment, a test vehicle and an open trailer. For the latter, wind speeds were measured in running conditions at the microphone positions and wind induced noise levels were estimated from data provided by the microphone manufacturer. The S/N ratio at 80 km/h on a AC 11d surface was estimated to be 23 dB in the one-third-band octave at 315 Hz and 36 dB for overall A-weighted noise levels. For the test vehicle, wind speeds and induced noise levels were measured directly on the whole system in an anechoic wind tunnel. Overall wind noise levels at speeds up to 90 km/h were at least 10 dB lower than tyre/road noise on porous asphalt 0/10. Both experiments demonstrate the validity of tyre/road noise measurements by uncovered systems.
