The suggested method requires no circulation of sound calibrators or measurements by the participants. The only requirement of the participants is that they submit a full statement of their uncertainty budget(s) for measurement of the sound pressure level of sound calibrators.
The following information is required to be submitted by the participants:
- categorisation of the measurement method(s) employed (ie insert-voltage or comparison technique)
- purpose of the measurement (eg calibration, periodic verification, pattern evaluation)
- description of the measurement (all relevant details eg number of replications, limits on environmental conditions and corrections applied)
- sources of measurement uncertainty
- magnitude of individual measurement uncertainty contributions
- method of combining contributions
- final uncertainty quoted
The pilot laboratory will compare each of the above aspects of the budgets. The methods of assessing uncertainties will be compared with those outlined in the GUM. The causes of the differences in claimed measurement uncertainties will be identified and, where applicable, the suitability of the measurements for use with IEC 60942:1997 and the latest draft version of IEC 60942:200x will be investigated.
Final report (NPL Report CMAM 73) has been completed and circulated to participants. Further copies can be obtained directly from Richard Barham.