Windshields With New PVB Interlayer for Vehicle Interior Noise Reduction and Sound Quality Improvement

Abstract

Noise transmission through automotive windshields is the subject of extensive laboratory acoustic and full scale high-speed track NVH evaluation. Standard windshields transmit structure-borne noise through resonances at low frequencies, and wind noise and airborne noise due to coincident effect at high frequencies. Approaches to enhance windshields NVH performance and to improve vehicle interior noise quality are explored. The study shows that the most effective approach is to design a new interlayer for windshields. This leads to the development of an acoustic grade PVB interlayer. To quantify the noise reduction by windshields with the new PVB interlayer, Solutia commissioned NVH testing of the windshields installed on cars, comparing these with factory-equipped standard windshields. Dynamic responses of the windshields were studied in laboratory on a dynamometer and resulting frequency response functions measured. A considerably high damping of resonant vibrations and significant reduction of structure-borne noise were noted. Further studies on the windshields for enhanced noise reduction, in particular wind and road noise, were conducted with several vehicles on high-speed test tracks. Test results show that the use of the windshields with new PVB interlayer results in 2 - 6 dB reduction in the cabin noise in high frequency range and up to 2 - 3 dB reduction in low to mid frequency range. Both subjective and objective results indicate that these windshields can greatly improve the vehicle wind noise and road noise performance and noise quality within the cabin, and result in the quieter passenger compartment.