Abstract
The passenger car total level of interior noise has been reduced in the last years; with the reduction of engine and rolling tires noise, the wind noise becomes more intrusive, so it s very important to have an instrument to identify and eliminate its sources. The objective is not only to reduce the overall level, but to shape the audible spectrum in the passenger compartment to psychoacoustic criteria.
FIAT Auto full scale Wind Tunnel was built 25 years ago, when the automotive aeroacoustic was not among the main activities of a wind tunnel as it is now instead. Therefore, the wind tunnel had to be improved through an acoustic treatment, so that the background noise in the test room could be reduced.
This first part of this paper describes by which criteria the modification have been defined and the main results achieved.
A low level background noise also permits to improve the test procedures as spectrum, loudness, sharpness and articulation index analysis; it permits to improve the quality of binaural acoustic head recording data and relative comparative jury tests .
The second part of this paper describes the standard test procedure adopted during the vehicle development and some future improvements.