For drivers, outside noise is most noticeable when entering a highway tunnel, where the concrete walls reflect sound into the car’s interior, where it rises to a roaring crescendo. Those in the car have to speak more loudly, and occasionally the sound system turns up the volume of the music and voice prompts. “These differences reveal the impact that outside noise can have on driving comfort,” says Jürgen Ochs, Head of Sound Quality, Car Bodies, at Porsche. “The type of glass in the vehicle plays a key role in acoustic comfort. And its effect can be precisely measured – whether on an exposed stretch of road or in a tunnel,” he explains. That’s why a sophisticated thermally and noise-insulated glass is available for all four-door Porsche models.
Unlike the conventional single-layer safety glass used for the sides and rear, this glass features five layers: glass, three layers of film, and then glass again. The middle layer of the three polyvinyl butyral (PVB) films has special acoustic properties that absorb much of the oscillation of the surrounding glass. This reduces outside noise by up to 7.3 per cent in a frequency range of 630 hertz to 6.3 kilohertz. “That doesn’t sound like much, but everyone who’s ever tested the difference in driving conditions is impressed,” continues Ochs. It effectively covers the range that the human ear is most sensitive to, which is approximately 3.5 to 4.0 kilohertz. Police, fire engine, and ambulance sirens remain just as loud as always, as they fall within the frequencies between 360 and 630 hertz virtually all over the world.
Noise-insulated glass in all windows
Porsche installs the noise-insulated glass throughout, including in the tiny triangular panes and, of course, the rear window. A secondary effect is that the acoustic glass weighs a little less than the standard offering. In the case of the Panamera, the reduction in weight is around two kilograms. In addition, the extra layer of film makes the glass more resistant to break-ins. The additional insulation can always be ordered in combination with the thermally insulated glass, which looks no different from the standard glass. The thermally and noise-insulated glass can, of course, also be combined with the ever-popular privacy glass. The lightweight glass option offers comparable noise reduction for two-door models.
Text first published in the Porsche customer magazine Christophorus, No. 401.
Author: Thorsten Elbrigmann
Illustration: Design Hoch Drei