Specification of requirements for the calibration of impedance heads for measurements on mechanical couplers

Progress Report, 12 August 2005

A project protocol was discussed at the sound-in-air SC meeting in Torino, May-05. The protocol was approved and a revised timescale agreed.


Impedance heads (e.g. Brüel and Kjær type 8000) are used to calibrate mechanical couplers which in turn are used to calibrate audiometers and provide traceability for measurements of bone conduction hearing level.

For this purpose a calibration of both the acceleration sensitivity and the force sensitivity of the impedance head is required. In order to develop a suitable calibration method a clear and full specification of the requirements for the calibration is required. The should derived from the practical needs of those involved in bone-conduction audiometry as well as those responsible for calibrating mechanical couplers and should consider both current and future needs. Consultation with practitioners is therefore essential before a specification for the calibration of impedance heads can be made.

This project therefore involves participants consulting with the audiometric community in their country and reporting on their requirements. Issues to be discussed include frequency range, uncertainty, approximate number mechanical couplers in service, frequency of calibration and other points deemed to be important to users. The pilot laboratory will then compile these comments into a report that recommends a specification of requirements for the calibration of impedance heads.

Further Information

[2005-08-12] This form was updated following discussions at TC-AUV 2005 (changes in bold).


[?] The project was agreed at the TC-AUV meeting in May-04, Vienna.

Acoustics, Ultrasound and Vibration (AUV)
Richard Barham, NPL (United Kingdom)
Coordinating Institute
NPL (United Kingdom)
Further Partners