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Model
CAL291
Under IEC and ANSI
standards, a sound intensity measuring system consists of a two
microphone sound intensity probe and a dual channel processor. The
accuracy of the intensity measurement is strongly dependent upon the
phase accuracy between the two measurement channels, including the
microphones. Sound intensity measurement systems are classified into
Class 1 or 2 based upon the pressure-residual-intensity index which
is measured using a residual intensity testing device. For direct
calibration or verification of the accuracy of a sound intensity
measurement system, IEC 1043 and ANSI S1.9 call for the use of a
sound intensity calibrator which delivers to the probe microphones
the simulated intensity at a specified temperature, atmospheric
pressure and nominal microphone separation.
The Larson Davis Model
CAL291 Residual Intensity Calibrator satisfies the residual
intensity test device specifications of both IEC 1043:1993 and ANSI
S1.9-1996.
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Testing of
sound intensity measurement systems |
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Generation of
signals for verification of the amplitude/phase
accuracy of multi-channel acoustic measurement
systems |
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Amplitude/Phase Normalization. The digital
filters of the Larson Davis 3000+ analyzer provide both
amplitude and phase, permitting the measurement of the
complex transfer function between two measurement
channels, including microphones, in 1/3 octave bands by
using the CAL291 to excite both microphones with
broadband noise. From this a correction function can be
generated within the analyzer to correct for any
amplitude and phase errors which may have existed
between channels previous to the normalization
procedure. |
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Applies the
same signal with zero phase difference to a pair of 1/2"
or 1/4" microphones |
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Driven by
external signal generators such as the following
versions available with the Larson Davis Models
2800/2900 and 3200 Real-time Analyzers: |
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OPT 10 Noise
Generator; pink or white broadband noise |
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OPT 11
Digital Signal Generator; Sinusoidal, pink or white
broadband noise, 1/3 octave bandlimited pink pseudo
random noise and white pseudo random noise |
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Amplifier
provides signal levels to 127 dB |
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CAL291 Residual Intensity
Calibrator