Holographic sound-field imaging as a diagnostic tool

Approaching its third decade, sound-field imaging using near-field acoustical holography has matured as an analysis technique. It has been established as the tool of choice for source motion mapping in structural acoustics and for source identification in noise control. The strength of near-field holography lies in its complete description of the sound field, from source to far field. This opens a door to using sound-field imaging as an acoustical diagnostic tool. Several current trends in applying holography, including moving sources, reverberant spaces, and lower-cost systems, are surveyed. New diagnostic applications of sound-field reconstruction in audio-source imaging, transmission path analysis, and boundary material characterization are described.