BRUEL & KJAER 4226 - Specifications and Compliance; Technical Specifications

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Chapter 5
Specifications
Specifications – Multifunction Acoustic Calibrator Type 4226
All values are typical at 25 °C (77 °F), unless measurement
uncertainty is specified. All uncertainty values are specified at
2 σ (that is, expanded uncertainty using a coverage factor of 2)
Calibration Function
NOMINAL SOUND PRESSURE LEVELS
94 dB, 104 dB and 114 dB
REFERENCE SOUND PRESSURE LEVEL
(at reference ambient conditions)
94 dB ±0.2 dB re 20 μPa, at 1 kHz
10 dB and 20 dB Level Step Accuracy: ±0.1 dB for f
≤8kHz;
±0.2 dB for f >8 kHz
NOMINAL FREQUENCIES
From 31.5 Hz to 16 kHz in octave steps, plus 12.5 kHz
FREQUENCY ACCURACY
±1% re the ISO 266 stated exact frequencies
FREQUENCY STABILITY
Better than ±30 ppm
REFERENCE AMBIENT CONDITIONS
Ambient Temperature: 20°C (68°F)
Ambient Pressure: 1013 hPa
INFLUENCE OF AMBIENT CONDITIONS
(at reference sound pressure level)
Ambient Temperature: +0.002 dB/°C in the range –10 to
+50 °C (max. temp. uncertainty ±5 °C)
Ambient Pressure: +0.00055 dB/hPa in the range 650 to
1080 hPa. For 114 dB SPL setting: 850 to 1080 hPa
(max. pressure uncertainty ±30 hPa
*
)
Magnetic Field Sensitivity: No observable effect (<0.01 dB)
at 100 A/m
FREQUENCY RESPONSE
Pressure Field: Linear (94 dB, 104 dB and 114 dB SPL) and
inverse A-weighting (94 dB SPL at 1 kHz)
Equivalent 0° Free-field: Linear (94 dB, 104 dB and 114 dB
SPL) and inverse A-weighting (94 dB SPL at 1 kHz)
LEVEL ACCURACY AT FIXED FREQUENCIES
(linear and inverse A-weighting)
Pressure Field (re 1 kHz):
31.5Hz to 125Hz: ±0.15dB
250 Hz to 500 Hz: ±0.10 dB
2kHz to 4kHz: ±0.15dB
8kHz: ±0.25dB
12.5 kHz to 16 kHz: ±0.5 dB
Equivalent 0° Free-field (re 1 kHz):
31.5 Hz to 125 Hz: ±0.2 dB
250 Hz to 500 Hz: ±0.10 dB
2kHz: ±0.2dB
4kHz: ±0.3dB
8kHz: ±0.5dB
12.5 kHz: ±1.0 dB
16 kHz: ±1.5 dB
TOTAL HARMONIC DISTORTION
≤3%
Additional Functions
TIME WEIGHTING TESTS
Frequency: 2kHz preselected
Test L evel: Typically 94 dB. Adjustable approx. ±12 dB
Signal: Continuous reference and toneburst
Level Between Bursts: Ref. level –20 dB
Burst Duration: 500 ms (S) and 200 ms (F)
CREST FACTOR TEST
Frequency: 2 kHz preselected
Test L evel: Typically 94 dB. Adjustable approx. ±12 dB
Signal: Continuous reference and toneburst of 40 Hz
repetition frequency. Crest factor 3 at preselected and
higher frequencies
✐Please note: All burst signals consist of an integral
number of sine waves with amplitude shifting at zero
crossing
DOSE METER CALIBRATION
Calibration Period: 30 s
* To satisfy IEC 60942 class 1 requirements