Internal noise control of the cabin of commercial aircrafts is an important issue in aircraft design. Analysis of transfer performance of noise and vibration of the full aircraft is the key technology. In this article, a method of measurement and analysis of transfer performance of noise and vibration for civil aircrafts based on the reciprocity principle was introduced. The LMS Test. Lab, the low-volume sound source, sound pressure and acceleration sensors were used to acquire the frequency response function, amplitude and phase transfer functions and the coherence function. The performances of noise and vibration transfer among the pylon, fuselage structure, interior trim and cabin cavity were analyzed. The feasibility of engineering application of this method for civil aircrafts was verified.

The orifices in thick microperforated panels (MPPs) are normally straight holes. Although the increase in thickness extends application field of MPPs, the eventually change of acoustic impedance leads to the decline of absorption coefficient. One way to improve this deterioration is to have variable axial section in thick MPPs. In this paper, varying section MPP molded by tapered and step-shaped molding core were prepared by using epoxide resin, and their acoustic characters were measured. Results showed expansion of absorption band in varying section MPP. Compared with conventional straight hole MPP, the absorption frequency range extended from 300~700Hz to 310~830Hz, and average absorption increased from 0.45 to 0.54 for tapered section MPP.