NOISE TRANSMISSION THROUGH A VEHICLE SIDE WINDOW DUE TO TURBULENT BOUNDARY-LAYER EXCITATION

This paper presents results of an investigation on noise transmission through an aluminum panel clamped to a greenhouse vehicle model subjec t to random acoustics, random vibration, and turbulent boundary layer excitations. Experiments on random acoustics and random vibration exci tations were carried out in a reverberation chamber, and those on turb ulent boundary layer excitation were conducted in the wind tunnel at t he Chrysler Technology Center. The transmitted noise spectra were also calculated using a single computer program VibroAcoustic Payload Envi ronment Prediction System (VAPEPS) based on Statistic Energy Analysis (SEA). The acoustic absorption coefficient (AAC) and the damping loss factor (DLF) for the vehicle were determined based on experimental dat a. Results showed that the largest differences between the measured an d calculated sound pressure levels in any frequency band above 500 Hz were less than 2.5 dB for random acoustics excitation, 5.0 dB for rand om vibration excitation, and 5 dB for turbulent boundary layer excitat ion. In spite of the presence of differences in individual frequency b ands, the calculated total sound pressure levels compared well with th e measured ones. The differences between the calculated and measured t otal sound pressure levels were 0.7 dB for random acoustics excitation , 0.4 dB for random vibration excitation, and 1.8 dB for turbulent bou ndary layer excitation.