New test, measurement and consulting possibilities in overall vehicle acoustics for customers in the Automotive region of Baden-Württemberg
This is why, for example, a premium German manufacturer entrusts his team with the development of overall vehicle acoustics for an entire vehicle platform and its derivatives. And this is already in the third generation of vehicles. The commitment has even been extended to another series now.
To provide key customers and new customers in the field of acoustic engineering with even more direct and fast support, Continental Engineering Services has invested in an acoustics center from TLT along with an acoustic test bench in Markgröningen, approximately 30 km north of Sindelfingen. Other well-known companies from the automotive sector are already active at the new location.
The all-wheel drive rolling road tester acquired in Markgröningen allows the acoustics of any vehicle to be measured and assessed in driving mode under constant, virtually real environmental conditions. The effects of a wide range of noise sources are investigated, such as the rolling noises of the tires on a wide range of asphalt surfaces or the engine sound at different speeds. For prototype vehicles in the premium segment, such as the Mercedes S-Class or the Maybach, the CES engineers keep an “ear” out primarily from the rear right seat position in order to localize audible disruptive noises from there.
As a first step, the subjective assessment by the acoustic engineer is crucial. If the disruptive noises are to be assigned to the door trim, for example, they are measured using a large number of sensors placed in the vehicle, such as single microphones, what are referred to as artificial heads or a special stethoscope.
The use of artificial heads allows binaural hearing, i.e. hearing with both ears to be reconstructed, meaning that disruptive noises can be measured objectively. After all, everyone hears differently, influenced by the size and shape of their head, their nose, and the different transit time of the sound between both ears. By positioning the measuring instruments in the same place all the time, comparable documentation of the sound fields can be achieved. This makes the work of the acoustic experts comparable and reproducible. This is because the vehicle prototypes are often not permanently available to the NVH team, i.e. individual work stages may have to be carried out after an interval. As a result of the logged measurement results, acoustic measures can be proposed to the customer in the form of material or component changes for dampening and isolation of the airborne or structure-borne sound, for example.
These are then installed in the corresponding areas, such as for example in the door trim, the front bulkhead, the headliner, the rear shelf area or the rear section of the vehicle, in order to prove their effectiveness.
In addition, in the newly acquired acoustics center, there are measuring devices that are used to characterize the structure-borne sound insulation characteristics of acoustic materials using what is referred to as the Oberst method: for example, a laser scan vibrometer or an alpha cabin.
In combination with the acoustic chamber already available at its home location in Frankfurt, Continental Engineering Services has the best conditions in place for acoustically evaluating and optimizing materials and components in accordance with automotive specifications, as well as helping vehicle manufacturers to improve the overall vehicle acoustics of their vehicles through material and component changes. After all, for premium vehicles in particular, overall vehicle acoustics are sometimes the decisive sales argument.
