Stripping the one-dimensional acoustic pressure response into propagating and standing wave components

Abstract

Most realistic boundary conditions are partially absorptive, with the rest of the incident acoustic power being reflected. This results in a response that can be viewed as a summation of propagating and standing wave effects. A one-dimensional, measurement-based, two-microphone spectral analysis technique is developed which Separates the Total acoustic Response Into Propagating and Standing (STRIPS) wave components. STRIPS uses measurements that contain implicit information about the boundary condition to extract the propagating and standing wave components. These sum to be the total system response without requiring explicit knowledge of the particular boundary condition. An exact decomposition example for a one-dimensional acoustic pressure model with a known mixed boundary condition is used to validate the STRIPS method. The utility of the STRIPS method is demonstrated using experimental measurements from a tube as input to STRIPS to obtain the propagating and standing wave pressure components. Changes in experimental boundary absorptivity are seen in the STRIPS results when a flared end is attached to the tube.