Developing New Methods for Obtaining Energy-based Acoustic Quantities

Brigham Young University, Provo UT

Investigators

Abstract

Although a microphone measures only pressure changes, multiple microphones can be used to extract significant information about acoustic energy flow, leading to more effective source and sound field characterization. This award will allow in-depth study of new methods for obtaining energy-based quantities from multi-microphone measurements, improving on traditional techniques that often require measurements be repeated with different microphone spacings. Initial development has already enhanced vector intensity measurements of rocket and military jet noise fields, but theoretical and experimental investigations will extend this work to other quantities in both enclosed and radiating sound fields as well as impactful applications. The effort will not only lead to improved and more efficient characterizations of sound sources and fields, but will be used to promote and further develop targeted activities to prepare a diverse, globally competitive workforce, support science education on all levels, and increase public awareness and appreciation of science through a broad outreach program. To improve frequency bandwidth of energy-based acoustical measurements made with multi-microphone probes, new calculation methods based on taking gradients of the amplitude and phase variation across the microphones will be developed. Signal processing procedures for different acoustic quantities will be obtained from analytical investigations and laboratory experiments will be used to assess performance gains for different acoustical environments, probe configurations, and processing methods. This work has diverse practical applications in engineering acoustics, noise control, architectural acoustics, and source localization and tracking, a few of which will be investigated as a result of this award. Improved sound power measurement procedures will impact source noise assessment across a broad range of industries. New acoustical holography methodologies will result in more efficient three-dimensional sound source and field characterizations. Additionally, plane-wave tube measurement methods used to characterize absorption and sound transmission properties of different materials may benefit from the work. These new methods for obtaining energy-based acoustical quantities from multi-microphone measurements will guide development of probe microphone configurations optimized for the calculation procedures and prompt reviews of current national and international measurement standards.