Calibration is a fundamental (but often overlooked) step in the process of measurement. It ensures that the instrument which is used for testing accurately indicates the required measurement parameter and that the instrument is performing to its specification.
For example, in audiometry, calibration ensures that the hearing level indicated by the audiometer complies with the British Standard specifying the reference for hearing thresholds.
There are two principles involved in any type of calibration work: Traceability and Uncertainty.
Measurement traceability describes how a calibration result (usually quoted on a certificate of calibration) can be traced back through a chain of calibrations to a national calibration standard.
Measurement Uncertainty is an estimate of the error associated with a calibration measurement and should take into account all the possible factors (environmental, equipment, human etc) that could affect the accuracy of the measured result. In general, the smaller the uncertainty the higher the accuracy of the calibration measurement.
The Acoustic Metrology Quality System ensures that every measurement that we quote on our calibration certificates is traceable and is accompanied by an appropriate uncertainty.