This paper presents a summary of recent studies of sound transmission loss of sandwich aircraft structures for global transportation applications. A review of the literature on the related research is given. Some research issues are identified that are important to reducing interior noise of aircraft for global transportation applications. Recent results of vibration and sound transmission loss are presented for a sandwich beam with anisotropic skin and core materials. The study has found a significant increase of the transmission loss for the sandwich beam with anisotropic materials as compared with isotropic ones.