Sound intensity transfer path analysis and its application to analyze the acoustics in vehicle interior

A new technology based on conventional transfer path analysis (TPA) called sound intensity TPA (SITPA) is proposed and applied to analyze the acoustic field in a vehicle interior excited by a pair of front speakers. First, we introduce an analogy of a mass-spring-damper system for our intuitive understanding of sound intensity. On the basis of the analogy, we determined that the active and reactive components of sound intensity represent energy transmission and storage in the acoustic field, respectively. Next, formulation of SITPA, which extends the capability of conventional TPA, is introduced and demonstrates how SITPA expresses the sound intensity at the receiver by using the sum of partial sound intensities transferred from multiple sound sources. Application of SITPA shows that the active and reactive components of partial sound intensities generated by the interference of front-left and front-right speakers can be changed by modifying not only acoustic transfer characteristics of the vehicle interior but also phase-lag of input signals for speakers. The effect of modifying the phase-lag on the sound intensity is experimentally examined under the scheme for minimizing and maximizing reactive sound intensity.