Examples of a pistonphone and a multi-frequency
calibrator

NPL Acoustics Group offers high precision UKAS-accredited calibration services for sound calibrators, including pistonphones and multi-frequency calibrators. Calibration is made using the insert-voltage technique* and NPL's own calibrated reference standard microphones, to accurately determine the sound pressure level generated at the diaphragm for any calibrator/microphone configuration. Calibrations using the insert voltage technique provide low uncertainties of measurement, which enable the calibrator, if desired, to be used as a reference to calibrate other sound calibrators or to calibrate microphones, as well as to check the sensitivity of sound level meters.

Calibrations can be performed for most well-known models of sound calibrator using microphones of IEC types LS1P, WS1P, LS2P, WS2P, WS2F and WS3P from well-known manufacturers.

Calibration is available in the range 31.5 Hz to 16 kHz, with a best measurement uncertainty of 0.04 dB for IEC type LS microphones, and 0.05 dB for IEC type WS microphones (depending upon calibrator/microphone configuration required).

Periodic testing is also available, in order to establish that the calibrator under test conforms to the requirements of its given class; specified in BS EN 60942:2003. This test verifies that the measured sound pressure level, frequency and distortion fall within the specified tolerences appropriate for the class of calibrator (LS, 1 or 2), making allowance for the measurement uncertainty.

An NPL Certificate of Calibration is issued, allowing traceability to national standards to be demonstrated. The frequency, sound pressure level and distortion generated by the calibrator under test are included on the certificate. Re-calibration at yearly intervals is recommended to maintain traceability. All testing at the National Physical Laboratory is underpinned by the requirements of ISO 9000, in which calibration and traceability feature prominently.

* Calibration for microphones of IEC type WS3P are by voltage-ratio technique.

Contact

Customer Service tel: +44 20 8943 8631
E-mail: acoustics_enquiries@npl.co.uk