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Due to increasingly stringent laws regarding the level of noise emitted by motor vehicles, especially when it comes from trucks, many techniques are used to determine the main source of noise. Levels must meet the standard pass-by noise as provided by the standard ISOR362. This work applies a technique that aims to identify the main source of noise of heavy vehicles during the pass-by noise test, called Pass-by Noise Beamforming. The technique use the method known as Generalized Inverse and an array of microphones optimized for low frequencies. The paper presents the steps of validation of the system using loudspeakers and application in two trucks with distinct contributions (engine and tire noise). The results of the technique showed advantages compared to the conventional method (delay-and-sum algorithm), obtaining better separation of coherent sources with better dynamic range in a wide frequency range (50 Hz - 7 kHz).