Beamforming Quantification of Acoustic Transmission Paths for Passenger Vehicles Using a Reciprocal Approach

This paper presents an experimental method for measuring transmission paths from the exterior to the interior of a passenger vehicle using a reciprocal approach: A production vehicle was placed in a semi-anechoic environment; artificial noise sources were placed at the location of the occupant’s ear(s) inside the vehicle and beamforming arrays with a total of more than 300 microphones were used to observe apparent noise sources on the vehicle exterior resulting from transmission paths. This makes it possible to quickly measure transmission paths over the whole vehicle body.

One of the motivations for this work is the monitoring of sealing quality on production vehicles. Artificial seal breaches were introduced on the vehicle and a number of excitation signals were assessed to develop a method to detect and localise leakage noise sources.

The investigation and methodology demonstrate the potential for the use of reciprocal beamforming to detect acoustic transmission paths with a view to identifying errors that would impact a vehicle’s wind noise performance, for instance in a manufacturing environment. In addition, it also shows benefits in the use of a similar approach for detecting non-leakage transmission weaknesses, which has applications including the comparison of the isolation performance of various vehicles to external noises.