Development of Acoustic Energy Concepts to Characterize and Control Acoustic Fields

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DEVELOPMENT OF ACOUSTIC ENERGY CONCEPTS TO CHARACTERIZE AND CONTROL ACOUSTIC FIELDSSommerfeldt, Leishman, and BlotterAbstractOver the past twenty years, acoustic intensity techniques have led to significant improvements in the understanding and characterization of acoustic fields. However, several fundamental questions associated with acoustic energy quantities, and their significance in characterizing and controlling sound fields still exist. This project will focus on investigating several energy quantities in enclosed sound fields to more fully understand their spatial dependence and how energy-based sensing and actuation can be used advantageously in a number of important applications. The specific objectives are: (1) Energy quantities including acoustic energy density, Lagrangian density, and their spatial derivatives will be analyzed in depth, as they apply to enclosed sound fields; (2) measurement techniques will be developed for measuring sound power, both in ideal (anechoic and diffuse) acoustic fields, as well as more general acoustic environments; (3) advanced active noise control concepts will be developed that further use energy-based measurements to improve the global control of acoustic fields; and (4) sound field equalization techniques will be developed using energy-based measurements and adaptive signal processing. This research will couple analytical, numerical, and experimental investigations. First, an understanding of the spatial dependence of these energy quantities and their spatial derivatives will be investigated analytically to identify the best energy quantities to measure for the different applications. Numerical work will extend these concepts to non-ideal conditions, and will be used to investigate how these energy-based concepts could be used in the target applications, and how they would be expected to perform. Finally, experimental verification of the concepts developed will be performed. This project will advance scientific knowledge through the discovery of new energy-based relationships and measurement techniques. This research has potential for significant societal benefits by enhancing noise control techniques in applications ranging from room acoustics to an aircraft fuselage. Through this research, future professionals will be trained with strong research skills and broad backgrounds in acoustics and structural dynamics. Graduate and undergraduate students will be involved on teams, and will learn to effectively interact with one another. These teams will be supported and encouraged to publish and present their research at technical meetings.