Audiometer calibration: interpreting and applying the standards

A degree of judgement is required when applying the British Standard associated with the calibration and performance of audiometers, BS EN 60645-1 (IEC 645-1). Consequently there is potential for variation of practice between calibration agencies. This note addresses issues and makes suggestions relating to the measurement of distortion, on-off effect, cross talk, linearity, rise/fall time and to the positioning of the earphone on an artificial ear. The degree of precision appropriate to each measurement is suggested. A warning is given of the audiological consequences of excessive distortion produced by normally functioning audiometers.