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 subject to random acoustics, random vibration, and turbulent boundary layer excitations. Experiments on random acoustics and random vibration excitations were carried out in a reverberation chamber, and those on turbulent boundary layer excitation were conducted in the wind tunnel at the Chrysler Technology Center. The transmitted noise spectra were also calculated using a single computer program VibroAcoustic Payload Environment 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 data. Results showed that the largest differences between the measured and 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 random vibration excitation, and 5 dB for turbulent boundary layer excitation. In spite of the presence of differences in individual frequency bands, the calculated total sound pressure levels compared well with the measured ones. The differences between the calculated and measured total sound pressure levels were 0.7 dB for random acoustics excitation, 0.4 dB for random vibration excitation, and 1.8 dB for turbulent boundary layer excitation.