A measurement study ear simulators being in use in Poland and the influence of their acoustic parameters on hearing tests and assessment

Abstract

Ear simulators are used for traceable calibration and testing of audiometric equipment. They should be periodically calibrated because their parameters can change over time affecting the results of audiometric equipment calibration and, consequently, the results of hearing tests and assessment. During calibration two acoustic parameters are determined: the overall pressure sensitivity level of the ear simulator system and acoustical impedance of the ear simulator, which is additionally assessed in terms of compatibility with IEC 60318-1:2009. The sensitivity level is used for assuring traceability of measurements while acoustical impedance provides information on the condition of a given ear simulator. There are two objectives of this paper. The first is to show how a change in acoustical impedance influences the response of the ear simulator system to a signal from an audiometric earphone. The other is to present the results of a measurement study on acoustic parameters of ear simulators in use in Poland. The article presents the results of measurements of the sensitivity level and acoustical impedance of ear simulators, and the assessment of simulators in the term of their suitability for calibration of audiometric equipment.