Sound Calibrators

Only a UKAS-accredited service is offered for the calibration of Sound Calibrators which accommodate a WS-2 microphone (half-inch diameter condenser microphones - which is the microphone standard normally used on a Type 1 sound level meter, regardless of make). The normal calibration offered is a measurement under monitored atmospheric temperature and pressure conditions of:

• Sound Pressure Level
• Frequency
• Total Harmonic Distortion

Each of the three measurements is reported on the calibration certificate together with the associated uncertainty of measurement as affirmed by the UKAS accreditation.

The sound pressure level is determined by the average of six independent measurements of the object calibrator in comparison with six measurements with each of two reference calibrators, both of which are regularly calibrated by the UK National Physical Laboratory.

Frequency of the object calibrator is determined as the average of six independent measurements of the calibrator output by means of a 61/2 digit Multimeter.

Total Harmonic Distortion is measured using three independent measurements using a third-octave analyser, with frequency response corrected as appropriate for the frequency response of the analyser, preamplifier, and measurement microphone (which has NPL-calibrated pressure response). Normally, only one level of a dual-level calibrator is measured - the lower of the two levels unless otherwise specified by the customer order - unless the customer order requires calibration of both levels.