Reproduction of sound field inside an aircraft mock-up for evaluating ANC devices

Abstract

The performance of active noise-canceling (ANC) devices is typically measured in a semi-anechoic or reverberant room. However, the evaluation in these rooms is not consistent with the conditions in a realistic environment such as an aircraft cabin. The requirement of a consistent test environment makes the measurement inside a real aircraft under operation conditions very difficult to implement. A solution is to reproduce the sound field in a mock-up. The aim of this study is to reproduce a spatial sound field inside an aircraft mock-up for better evaluating the performance of the ANC devices (two earphones and two headphones). The target sound field was measured with 32 microphones scattered in a real aircraft under taxi condition. The reproduction used a multichannel least-mean-square algorithm which was improved with feedback controls. A head and torso simulator was then used to evaluate the performance of the ANC devices. The results showed that the performance was heavily influenced by the spatial characteristics of the sound field. This developed method is an efficient and effective way of reproducing sound field for evaluating more accurate performance of ANC devices in a more realistic environment than laboratories of semi-anechoic and reverberant rooms.