A car vendor in Berlin needed help with NVH analysis. When customers brought in their recently purchased cars because of a disturbing squeak and rattle noise while driving, the vendor's engineers were not able to locate the source of noise. The NVH measurement (Noise Vibration Harshness) with the Acoustic Camera provided the solution.
During a measurement session various methods were applied in order to pinpoint noise sources inside of the cars. As the subjective opinions about the origin of certain noise differed, the Acoustic Camera came in handy to reliably locate the unknown squeak and rattle sources.
VW Tiguan, VW EOS and VW Golf
For the measurement, the microphone array and the data recorder were positioned in the cabin of each car. The mobile power supply was set up in the trunk of the car. All measurements were conducted while driving on the road to capture real-life conditions. Afterwards, the acoustic images resulting from the channel data measured were mapped onto the vehicles' 3D models and each vehicle cabin was evaluated.
The acoustic hotspots were located at the roof of the car (Fig. 1). Crack was audible regularly at maximum sound pressure level of 39.9 dB(A). Also a second source was localized under the seat (Fig. 2). In the spectrogram, you can see the frequency range of the source marked from 1.7 to 5.7 kHz at a maximum level of 33.1 dB(A).
A squeal in the C-pillar of the electric roof was located emitting noise at 1.8 to 9.8 kHz. The channel data and the spectrogram with marked frequency band and associated acoustic 3D photo show several sources on the roof top.
Unusual squeaking noise located above the driver seat with a peak level of 68.1 dB(A). Acoustic hotspot is shown on the CAD model of the car.
