Realization and dissemination of the sound pressure unit (Pa)
The realization of the unit of sound pressure, Pascal, by means of the reciprocity calibration of laboratory standard microphones (IEC 61094-2, 61094-3) traces the acoustical unit 'Pascal' back to mechanical and electrical quantities. According to the application of the microphones, the pressure sensitvity (e.g. for a microphone used in the ear canal of an ear simulator) or the free-field sensitivity (e.g. for a microphone used with a sound level meter) are measured with basically different measurement set-ups in the frequency range from 31,5 Hz to 20 kHz (pressure sensitivity) resp. 500 Hz to 30 kHz (free-field sensitivity).
For the dissemination of the unit 'Pascal' sound calibrators or condenser microphones, which themselves were calibrated by secondary procedures (eg. IEC 61094-5), are used (tracable to the national reference). See this page for microphone calibration offers in our section).