The PLACID Long-Term Stability Programme provides independently documented evidence of measurement microphone sensitivity stability over time. Reference microphones representing each model in the PLACID range are held in our controlled laboratory under stable temperature and humidity conditions and measured quarterly using ISO/IEC 17025 accredited calibration methods. The resulting sensitivity time series is published so that users can incorporate this stability evidence into their quality management system documentation.
Long-term sensitivity stability is a critical but often undocumented aspect of measurement microphone performance. A microphone might have excellent sensitivity at the time of initial calibration but drift significantly over the following two years. If the stability of the instrument between calibration intervals is not demonstrated, the measurement uncertainty budget for that interval cannot be properly closed. The PLACID stability programme provides the published data that allows users to quantify the stability contribution to their uncertainty budget.
Users can reference the PLACID stability programme data in their quality management documentation and measurement uncertainty budgets as evidence that the sensitivity drift between calibration intervals is bounded. For ISO/IEC 17025 accredited testing laboratories, this can be used to support the Type B uncertainty contribution from calibration interval drift. For ISO 9001 quality management systems, the stability data supports the justification of the chosen recalibration interval.
Users of PLACID reference microphones can access the stability programme data for their specific model at any time by contacting the calibration team. The data is provided as a PDF report and a CSV file with the quarterly sensitivity readings and an uncertainty estimate for the trend line. For ISO/IEC 17025 accredited testing laboratories undergoing periodic assessment, this data supports the calibration interval justification documentation required by assessors.