3D sound intensity measurements: accuracy enhancements with virtual instrument based technology

Sound intensity can be evaluated by means of pressures measured by two microphones. With the use of four or six microphones one can measure the three-dimensional sound intensity vector. Measurements carried out in this way are subject to errors due to various causes. Aim of this paper is to describe a novel method (based on virtual instruments) for a real time correction of such errors. The correction algorithm compensates errors due to metrological characteristics of the transducers and measurement chain: sensitivity, phase response, microphone directional characteristics and interchannel delay. The effects of environmental conditions, namely pressure, humidity and temperature, can also be compensated.