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	Beamforming	BEM Acoustics	Impedance Tube
Ämnesområde	Akustik	Akustik	Akustik
Familj	Process / pipeline	Process / pipeline	Process / pipeline
Ursprungsår	1988	1971	1866
Upphovsperson	Van Veen, Barry Buckley	Carlos Brebbia, Robert Butterfield	August Kundt
Typ	Directional audio array processing	Computational simulation for acoustics	Acoustic absorption measurement
Ursprungskälla	Van Veen, B. D., & Buckley, K. M. (1988). Beamforming: A versatile approach to spatial filtering. IEEE ASSP Magazine, 5(2), 4–24.	Burton, A. J., & Miller, G. F. (1971). The application of integral equation methods to the numerical solution of some exterior boundary-value problems. Proceedings of the Royal Society A, 323(1553), 201–210.	ASTM E1050-19 (2019). Standard Test Method for Impedance and Absorption of Acoustical Materials Using a Tube, Two Microphone and a Digital Frequency Analysis System. American Society for Testing and Materials.
Alias	beamformer, spatial filtering, microphone array, phased array	BEM, boundary element method, indirect BEM, direct BEM	kundt tube, resonance tube, acoustic absorption, sound absorption coefficient
Närliggande	5	5	5
Sammanfattning	Beamforming is a spatial signal processing technique that uses microphone arrays to selectively enhance sound from a desired direction while suppressing sounds from other directions. Formalized by Van Veen and Buckley in 1988, beamforming is fundamental to hands-free speech communication, hearing aids, sonar, radar, and spatial audio recording. It enables 'listening' with directional sensitivity despite using omnidirectional microphones, by exploiting time delays and phase differences between array elements.	The Boundary Element Method (BEM) is a numerical technique for solving acoustic wave equations in complex geometries. Unlike finite element methods (FEM) that mesh entire volumes, BEM discretizes only the acoustic boundaries (surfaces), reducing computational cost and memory. First applied to acoustics by Burton and Miller in 1971, BEM is widely used for predicting room acoustics, exterior noise radiation, and acoustic scattering without the need for volumetric meshing.	An impedance tube (or Kundt tube) is a laboratory apparatus for measuring the acoustic absorption coefficient and surface impedance of materials. Originally developed by August Kundt in 1866, the technique has been standardized by ASTM and ISO for characterizing noise-control and acoustic-treatment materials. The impedance tube method is simple, portable, and cost-effective, making it the industry standard for pre-design acoustic material selection and quality control.