Uses
- Measurement and verification of pressure-residual intensity index
- Sound-pressure calibration at 251.2 Hz (Type 1 IEC 60942)
| Features
- No need to dismantle the probe when calibrating
- Optimised for use with Type 2260 E Investigator sound-intensity system for phase enhancement
- A complete sound-intensity calibrator in one unit
- Built-in sound source for sound-pressure calibrations with acoustic-feedback system to automatically adjust for variations in atmospheric pressure
- Built-in broad-band sound source for pressure-residual intensity-index measurements
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Introduction
Sound Intensity Calibrator Type 4297 enables instruments which measure sound intensity to be accurately calibrated.
Type 4297 is intended for use with Brüel & Kjær Sound Intensity Probes Types 3583, 3584 and 3595 (or earlier Types 3545 or 3548) with Sound Intensity Microphone Pair Type 4197 (or earlier Type 4181). The microphones must be used with ¼" preamplifiers.
The Sound Intensity Calibrator can be used for calibration of sound-pressure sensitivity. To do this, the microphones are both positioned in the calibration chamber. There is no need to dismantle the probe, and both microphones are exposed to exactly the same sound pressure (amplitude and phase).
The broad-band sound source is provided 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.
A barometer is not needed because an accurate feedback system holds the sound-pressure level at a constant value.
Calibration Procedure
Calibration of an intensity measuring instrument includes:
Sound-pressure Calibration
With the probe in the calibrator as shown in Fig. 1, the sound source produces the same sound-pressure level at each microphone. The microphone channels are calibrated against this known sound-pressure level.
Pressure Residual-intensity Index Measurement
Small differences in the phase responses of the microphones and input channels result in the detection of ®residual intensity”. Residual intensity is a parameter that should be taken into account when interpreting measured intensity data. The pressure residual-intensity spectrum is not fixed; it is ®tied” to, and rises and falls with, the measured sound-pressure level.
Fig. 1 shows an arrangement for measuring the pressure...
For a full Description and Specifications, see Product Data
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