intensity measurement with two microphones spaced by a short distance

This software determines the magnitude sound intensity vector by a measurement with two microphones

The sound intensity energy represents the flow through a given surface. The main advantage of this parameter lies in its independence with the acoustic environment. When it is desired to characterize the sound field produced by vibration sources usually the sound pressure level is used, this being dependent parameter of the power source, the spatial position and physical environmental conditions, on the other hand the parameter Loudness only it depends on the sound power of a source that passes through a given surface thus being able to make measurements in situ source analysis.
The main applications of sound intensity are:

● Determination of the power of a sound source

● Identification of noise sources and sound fields display

● Measurement of sound reduction index

● Measurement of sound pressure level emission

● Measurement of sound absorption.

Currently the work is aimed at developing a measurement system that allows for sound intensity academic activities given the scarcity of this instrument in college. What is presented here is a prototype instrument using equipment available at the university: Two Class 1 sound level meters, analog-digital converter card and a computer. The technique used consists of two microphones located in face to face configuration, mechanically mounted through the prototype probe. The calculation of the intensity is from the imaginary part of the cross spectrum between the two signals. To enable this measurement developed using MATLAB software (programming language that allows data acquisition from a digital analog converter card). For proper evaluation of the sound intensity it is necessary for both channels, considering the entire measurement chain, have similar behavior in amplitude and phase. To do so controlled measurements of each element of the measuring chain and a small phase shift between the signals of calculation were made, showing consistent and common to the expected results.

The inherent accuracy standardization of a measuring instrument than an academic scale requires the development and construction of parts for industrial use specific needs, thereby requiring financial support. This project represents a technological breakthrough for industrial applications of in situ measurements and on the other hand the substitution of imports of equipment by one fully national development.
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