Nonlinear wave propagation in horns and ducts

The one-parameter sound field of finite amplitude is modeled by an acoustic transmission line model and by block-oriented system models containing dynamic linear and static nonlinear subsystems. The transmission line model is based on conical elements and each element is represented by a linear four-port and a nonlinear source of volume velocity derived from the nonlinear wave equation in Lagrangian coordinates. The block-oriented system model with a lattice structure shows the forward and backward propagating sound-pressure waves separately. A simplified overall model and the derived higher-order system functions based on the Volterra approach describe the relation between the sound pressure at two points in the sound field. The presented models are the basis for numerical simulations, nonlinear system identification, and signal processing related to the nonlinear sound propagation in horns, ducts, and other acoustical systems with a nearly one-parameter sound field.