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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
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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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