Beamforming is a means of localizing the sources of sounds by processing signals produced by an array of microphones that are placed in a predefined pattern. The technology uses modern high-speed electronic data acquisition and processing capabilities in conjunction with the basic principles of fluid acoustic physics which have been understood for centuries. By harnessing the power of high-frequency simultaneous sampling over multiple channels, the time-of-flight differences between microphones are compared with the expected delays produced by all points in the localization field. When combined with the modern technologies of video camera reference and 3D modeling, acoustic beamforming allows for the fast identification of noise source locations in complex systems.
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.