Browse Publications Technical Papers 2008-36-0507
2008-03-30

Noise Reduction and Sound Quality Improvement with Acoustic Windshield 2008-36-0507

Windshields, with their low internal damping, are an acoustical weak link in automotive glazing. In the past, acoustically-enhanced glass products were typically achieved by utilizing solid and mass product design elements to increase the glass thickness. This is no longer acceptable as automakers are interested in weight savings, especially as they develop vehicles that are more fuel-efficient. Laminated safety glass, with a standard polyvinyl butyral (PVB) interlayer, is used extensively for automotive windshields and side glazing, and offers improved acoustical performance over tempered glass. However, the standard PVB interlayer is not designed specifically for acoustical and Noise, Vibration and Harshness (NVH) purposes. Studies of the parameters affecting acoustical properties and actual noise reduction capability of standard laminated glass led to the development of an acoustical grade PVB interlayer.
Dynamic responses for windshields made with acoustical grade PVB were studied in the lab with considerably high damping of resonant vibrations and a significant reduction of structure-borne noise noted. It also exhibited improved acoustics in the 1500 Hz to 6000 Hz frequency region, which is a key region for wind noise and airborne noise transmission, and a weight savings of up to 15%. Further studies on the acoustic windshields to measure for enhanced wind- and road-noise reduction were conducted on high-speed test tracks. Test results show the acoustic windshields reduce cabin interior noise in the high-frequency range by up to 6 dB and in the low-to-mid frequency range by up to 2-3 dB. Subjective and objective results indicate windshields made with acoustical grade PVB can greatly improve vehicle wind- and road-noise performance, and overall in-cabin noise quality, resulting in a significantly quieter passenger cabin with an important overall vehicle weight savings.

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