Apart from road noise, which has been acknowledged as the most cabin-intrusive sound in a passenger car - though its largely dependent on road surface, tyre or wheel size, and brand/block pattern of tyre - wind noise has been acknowledged as the next most disturbing sound for occupants.
“Right from the outset in the early stages of developing the latest-generation S-Class, we wanted reduce the level of wind noise inside the cabin. We decided to focus on wind noise, as there are simply too many variances in-play to effectively reduce road noise. The other thing, is that most people are used to road and tyre noise these days," explained Dr Woll.
“At 100km per hour wind noise becomes conspicuous, but at 140km/h there is only wind noise, so that’s the speed at which we optimised the car for wind noise. We also measured the noise levels at 90km/h and 200km/h, but 140km/h is the speed we settled on," he added.
In order to reduce the wind noise, the Mercedes-Benz acoustics team first had to identify the main sources of that noise.
“You have two major sources of wind noise; one is the A-pillar, and the second is the exterior mirrors. In order to reduce the noise, you need to optimise the path of these disturbances. So we had to look at things like bodyshell rigidity and all the various window and door seals, which we re-engineered to reduce high frequency noises that are most annoying inside the cockpit.
“We also looked the door glass, which is now double-laminated on all S-Class model models using two sheets of glass that are 2.6mm thick separated by 0.8mm sheet of special acoustic Polyvinyl Buttyral (PVB)."
The specially laminated glass is also optionally available on the new-generation C-Class range from around 200 euro ($290), which arrives in Australia in August.