Recent application of coupled-room systems in performing arts spaces has prompted active research on sound fields in these complex geometries. This paper applies a diffusion-equation model to the study of acoustics in coupled-rooms. Acoustical measurements are conducted on a scale-model of two coupled-rooms. Using the diffusion model and the experimental results the current work conducts in-depth investigations on sound pressure level distributions, providing further evidence supporting the valid application of the diffusion-equation model. Analysis of the results within the Bayesian framework allows for quantification of the double-slope characteristics of sound-energy decays obtained from the diffusion-equation numerical modeling and the experimental measurements. In particular, Bayesian decay analysis confirms sound-energy flux modeling predictions that time-dependent sound-energy flows in coupled-room systems experience feedback in the form of energy flow-direction change across the aperture connecting the two rooms in cases where the dependent room is more reverberant than the source room.

Ocean and lake floor survey is most efficiently conducted by active sonar owing to its favorable propagation range under water relative to other sensing modalities. Range however must be traded for resolution, yielding sonar return imagery that challenges both operator and machine to match returns to specific objects. In the case of certain objects, time-range extent in echo imagery may be exploited by machine learning detection and classification methods. This talk describes the success of such a method when applied to data collected from a low cost autonomous platform. Further capabilities such as decision support and detection geolocation are discussed. [This material is based upon work supported under Air Force Contract No. FA8721-05-C-0002 and/or FA8702-15-D-0001. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the U.S. Air Force. Presentation may contain distribution limited material.]

Acoustic performance for an interior requires an accurate description of the boundary materials' surface acoustic impedance. Analytical methods may be applied to a small class of test geometries, but inverse numerical methods provide greater flexibility. The parameter estimation problem requires minimizing prediction vice observed acoustic field pressure. The Bayesian-network sampling approach presented here mitigates other methods' susceptibility to noise inherent to the experiment, model, and numerics. A geometry agnostic method is developed here and its parameter estimation performance is demonstrated for an air-backed micro-perforated panel in an impedance tube. Good agreement is found with predictions from the ISO standard two-microphone, impedance-tube method, and a theoretical model for the material. Data by-products exclusive to a Bayesian approach are analyzed to assess sensitivity of the method to nuisance parameters.

The use of points of overdetermination, so-called CHIEF points, in numerical solutions to exterior Helmholtz problems for the elimination of spurious modes is well established. Further, the number and relative position of such points in two-dimensional radially symmetric geometries has been demonstrated theoretically. Since CHIEF points require lower computational overhead than collocation nodes, strategic use represents an opportunity for the improvement of predictions with maximal efficiency. Given the differing uniqueness properties of solutions to the interior and exterior problems, the former allows for development of optimization in the absence of competing priorities. Theory for two- and three-dimensional analytical cases is developed and subsequently extended to general geometries. Localization with respect to subdomains of spatial decomposition is investigated as well.

Higher-order finite difference methods for the solution of the wave equation are well established. The interchangeability of temporal and spatial derivatives allows for exact representations of the differential equation in difference forms to the order of accuracy desired. Realistic impedance conditions, however, germane to problems of an architectural acoustics origin, are typically given as ratios of pressure and velocity in the frequency domain. This work develops fourth order-accurate time domain boundary conditions for the types of materials typically encountered in the architectural acoustics field. Accuracy and agreement of numerical simulations to scale model measurements are compared and discussed, as is computational cost relative to lower-order methods.