Lumped Modeling of Far-Field Sound Propagation for Airborne Acoustic Transducers Using Acoustic Transmission Lines

In this work, a physics-based equivalent circuit model is derived and verified which allows to describe the sound propagation of acoustic waves emitted by airborne acoustic transducers such as microspeakers or micromachined ultrasonic transducers (MUTs). The presented approach is derived from an acoustic transmission line (ATL)-based description. The model can be implemented into conventional circuit simulators and, thus enable a faster and computationally cheaper simulation of the sound pressure emitted by airborne transducers as compared to finite element method (FEM)-based approaches. The derived model is further applied to an equivalent circuit model of a piezoelectric MUT to verify its precision and applicability. Characterization results of the sound pressure measured at various distances within an anechoic free-field chamber are compared to corresponding lumped element modeling (LEM)-based simulations showing a high accuracy of the derived ATL-based model.