An alternative approach to the measurement of the acoustic transfer impedance of the IEC 60318-1 ear simulator

Ear simulators are important measurement devices for characterizing the performance and acoustic output of earphones and other transducers designed to be coupled to human ears. For best practice in the use of these devices it is important that the acoustic transfer impedance is periodically tested against published specification. This practice has been facilitated by IEC 60318-1:2009, where a test method has been specified. This paper reports an alternative method offering simplifications in concept and implementation, and leads to improved measurement uncertainty. A comparison of impedance measurements on a sample of ear simulators shows that the two methods produce equivalent results, and that the proposed method offers a viable alternative to that given in IEC 60318-1.