Holography

Acoustic holography is a technique for determining the radiating structural acoustic behavior of surfaces by measuring in the acoustic nearfield. A complex 2D measurement of the acoustic field is made in the domain of evanescent wave behavior. Using a wavenumber-domain Fourier Transform and applying wave propagation theory results in a complete description of the structure's acoustic field in three dimensions, yielding computations of sound pressure, particle velocity, and sound intensity. A variety of algorithms exist for establishing the acoustic hologram, including the Statistically Optimized Nearfield Acoustic Holography (SONAH) and the Helmholtz Equation Least Squares (HELS) method.