TYPE 4231

Sound Calibrator

B&K Class 1 Sound Level Calibrator is designed for accurate in-field acoustic calibration of sound level meters, microphones and other sound measurement equipment.

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Type 4231 is a a handy, portable sound source for acoustic calibration of sound level meters and other sound measurement equipment. The sound calibrator is very stable and conforms to IEC/EN 60942 (2017) Class 1, and ANSI S1.40–2006.

Twin sound pressure levels guarantee definitive checks even in noisy environments and ensure linearity in your microphones. For maximum confidence in your measurement results,you can quickly compensate for local measurement conditions by calibrating before every measurement.


  • Calibration of sound level meters
  • Calibration of microphones
  • Calibration of general sound measurement instrumentation


  • Robust, pocket-sized design with highly stable level and frequency
  • Calibration accuracy ±0.2 dB
  • 94 dB SPL or 114 dB SPL for calibration in noisy environments
  • Extremely small influence of static pressure and temperature
  • Sound pressure independent of microphone equivalent volume
  • 1 kHz calibration frequency for correct calibration level independent of weighting network
  • Fits Brüel & Kjær 1″ microphones (1/2″, 1/4″ and 1/8″ microphones with a microphone adaptor)
  • Switches off automatically when removed from the microphone
IEC/EN 60942 (2017) Class 1
Calibration pressure
94 and 114 dB
Calibration frequencies
1000 Hz
Calibration accuracy
±0.2 dB
1-inch, 1/2-inch and 1/4-inch