THE FOCUSSED VERTICAL ARRAY FOR THE DESCRIPTION OF THE NOISE SOURCES ON A MOVING CAR

Knowledge of the height of sources concerns vehicle description as input parameter for traffic noise prediction models and design of noise barriers. The beamformed array has become a common measurement device for locating noise sources on vehicles. It is pointed out how measuring over reflecting road surface may disturb the interpretation of beamforming results. A passenger car is studied over a wide range of driving conditions (speed, gear, engine rpm). The main part of noise is coming from an area located under the car chassis. It includes rolling noise and mechanical noise, whose relative weight depends on speed and gear. A second weaker source is located near the upper part of the front wheel, and cannot be attributed to the motor noise only. For the covering abstract see ITRD E107776.