Study of the Noise Contributors on the Interior Acoustic of a Car and Their Countermeasures

This paper shows that the collaboration between a glass manufacturer and a passive acoustic treatment manufacturer can bring different benefits and considerably improve the interior acoustics of a vehicle. In terms of passenger safety and well-being, glazing have always played a key role by offering solutions to interior comfort, particularly when it comes to heat and acoustics. Today, cars are becoming a living space which from an acoustic point of view brings a challenge for the interior comfort. Indeed, glazing has no absorption and classically it has an acoustic insulation weakness around its coincident frequency. In most of the cases, these different aspects make glazing one of the main contributors to the sound pressure level in the passenger compartment, and the trend is not one of change. However, there are possible countermeasures. One of which is the use of laminated glazing with acoustic PVB. This solution allows to reduce the loss of insulation performance at the coincidence frequency. The other is the usage of passive interior acoustic trims. When properly positioned and optimized, the latter can be very effective and can tackle the frequency range that poses a problem. Especially since some technologies allow, by their process, to properly balance acoustic insulation and absorption. The aim of this paper is to understand the impact of the glazing on the interior acoustics for different types of excitations. For this purpose, a measurement campaign together with some simulation models (FE and SEA) have been carried out on a European C-segment vehicle. A ranking of the different contributions is proposed. Then, in a second part, the countermeasures to improve the interior sound pressure level by adding optimized glazing and sound packages are presented.