Pressure-Residual Intensity Index - BRUEL & KJAER 4297 User Manual

Sound intensity calibrator

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Table Of Contents

Table of Contents

The information below is valid for intensity measurement systems which use probes equipped

with pressure-sensing microphones and which work out the intensity in accordance with the

described principle.

✐

Even under laboratory conditions, it is very difficult to create a free-field situation where

Please note:

the angle between the propagation of the sound wave and the probe axis is exactly 90°.

However, for practical applications, this situation can easily be simulated using the set-up

shown in Fig. 1.2.

Fig.5.1

Setup for simulating a

free-field situation where

the angle between the

propagation of the sound

wave and the probe is

exactly 90°

1) A sound wave is incident on a probe axis at 90°. There is no flow of acoustic energy along the

probe axis. The signals from the microphones are in phase and no intensity is detected.

2) If a sound wave is incident at an angle other than 90°, then acoustic energy flows along the

probe axis. The microphone signals are out of phase and intensity is detected.