Cabin noise measurements with microphone arrays and sound intensity probes

Abstract

Aircraft cabin noise measurements in flight are necessary to characterize the acoustic experience in the cabin. The goal is to quantify the noise level, to identify the entry point of acoustic energy into the cabin, and to identify the noise source. Measurements were done in the ground-based Dornier 728 cabin noise simulation system. This system produces a realistic in-flight cabin sound field by 78 distributed vibration exciters on the back of the cabin lining. The measurements were conducted using an array of 30 microphones at different positions and synchronized afterwards to establish a virtual array with 420 microphones. Beamforming and source integration methods are used to derive an acoustic intensity level from the array measurements. As a reference, the acoustic intensity was measured using a pp-probe and the results are compared with the ones obtained using the array.