Evaluation of Acoustic Coupler for Audiometric Tests of Newborns

The acoustic coupler designed for newborn hearing assessments has been studied and used in in vitro tests. The acoustic transfer impedance (ATI) of the coupler was determined and compared with the theoretical model. In addition, its sensitivity to environmental conditions such as temperature and pressure was investigated at frequencies between 100 Hz and 10 kHz. Ear coupler has been compared with the IEC 60318–4 ear simulator and a 2 cm3 coupler and the results have been investigated. This paper reports on the results of experimental investigations for the new neonatal occluded ear simulator including in various atmospheric pressure and temperature conditions which was applied in automatic controlled environmental chambers. The uncertainty in the calibration is calculated in accordance with the methods specified in the “Guide to the Expression of Uncertainty in Measurement (GUM, ISO, 2nd edition, 1995)” and EA-4/02 (EA, 1999). A model function based on error has been created for the uncertainty calculations in the acoustic transfer impedance calculations and a detailed uncertainty budget has been given.