Acoustic Parameters of IEC 60318–1 Ear Simulators: A Comparison of Measurement Methods

Ear simulators, often called “artificial ears”, are important devices for objective evaluation of the acoustic performance of supra-aural and circumaural earphones, used for example in audiometry and telephonometry. They are widely used for calibration of audiometric equipment. In the paper the methodology for calibration of ear simulators specified in IEC 60318-1, implemented in the Central Office of Measures, is presented. There are two acoustic parameters that should be determined during calibration: the acoustical impedance of the ear simulator and the overall pressure sensitivity level of the ear simulator's microphone and associated measuring system. Different measurement methods for determination of these parameters have been investigated and the results of measurements as well as assessment of the selected ear simulators are presented. The measurement set-ups and problems that may occur during calibration are also discussed.