Technical Reviews

A method for measuring the normal incidence transmission loss and related acoustical properties of a sample placed in a four-microphone standing wave tube is described.

Dyn-X Technology, Order Tracking, and Comparison of IBEM PNAH and LDV Methods

Acoustical Solutions in the Design of a Measurement Microphone for Surface Mounting; Combined NAH and Beamforming Using the Same Array; Patch Near field Acoustical Holography Using a New Statistically Optimal Method

This article explains the basic principles of Beamforming, including the main performance parameters Resolution and Sidelobe Level. Special attention is given to the influence of array design and to cross-spectral beamforming. Different array designs, including Brüel&Kjær’s newly patented wheel array design, are described and compared, and the basic principle of Brüel&Kjær’s geometry optimisation method is outlined. A new, improved version of cross-spectral beamforming used in Beamforming Software Type 7768 is introduced and its benefits are verified. The article also provides some guidelines for performing good measurements and finally, describes a set of measurements representing typical applications.

The Influence of Environmental Conditions on the Pressure Sensitivity of Measurement Microphones; Reduction of Heat Conduction Error in Microphone Pressure Reciprocity Calibration; Frequency Response for measurement microphones – a question of Confidence; Measurement of microphone random-incidence and pressure-field responses and determination of their uncertainties

This article explains the basic principles of Beamforming, including the main performance parameters Resolution and Sidelobe Level. Special attention is given to the influence of array design and to cross-spectral beamforming. Different array designs, including Brüel&Kjær’s newly patented wheel array design, are described and compared, and the basic principle of Brüel&Kjær’s geometry optimisation method is outlined. A new, improved version of cross-spectral beamforming used in Beamforming Software Type 7768 is introduced and its benefits are verified. The article also provides some guidelines for performing good measurements and finally, describes a set of measurements representing typical applications.