Uses
- Sound intensity and particle velocity calibrations
- Sound pressure calibration
- Measurement of pressure-residual intensity index
| Features
- Intensity coupler for simulating a plane sound wave in a free field (US. pat. No. 4715219)
- Pistonphone for sound intensity, particle velocity and sound pressure calibrations
- Broad-band sound source for pressure-residual intensity index measurement
- sound pressure calibration of the individual microphone channels
- sound intensity and particle velocity calibration
- measurement of the pressure-residual intensity index spectrum of the system.
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Type 3541 is intended for use with Brüel & Kjær Sound Intensity Probes Types 3583 or 3584 (or earlier Types 3545 or 3548) with a Sound Intensity Microphone Pair Type 4181. Other microphone pairs have much higher vent sensitivities and this restricts their use; see ®Microphones and Vent Sensitivity”.
A simplified cross-section of the intensity coupler is shown in Fig. 2. It consists of two chambers connected by a coupling element. When the pistonphone is attached to the coupler there is a phase difference between the sound pressures in the upper and lower chambers. The amplitude of the sound pressure is the same in both chambers, so a plane sound wave propagating in a free field is simulated. If one microphone is positioned in the upper chamber and the other in the lower chamber, then the simulated sound wave can be used for calibrating the sensitivity of the measuring instrument to sound intensity and particle velocity.
The coupler and pistonphone can also be used for calibration of sound pressure sensitivity. For this, the microphones are both positioned in the upper chamber. Then they are exposed to exactly the same sound pressure (amplitude and phase).
The broad-band sound source is supplied for measurement of the pressure-residual intensity index spectrum. This is used to assess the accuracy of sound intensity measurements.
A calibration chart is supplied which states the levels that should be detected during calibration. The chart also gives information about corrections to the calibration levels for use when conditions are different from the stated reference conditions. A correction barometer determines correction terms to the sound pressure and particle velocity calibration levels due to changes in atmospheric pressure. The sound intensity calibration level is independent of any change in atmospheric pressure.
Calibration Procedure
Sound pressure calibration
Sound intensity and...
For a full Description and Specifications, see Product Data
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