The relation between the impedance at the microphone and the transfer impedance of an occluded ear simulator

The ANSI S3.25‐1979 Standard for an occluded ear simulator specifies the transfer impedance, that is the ratio of the pressure at the measuring microphone to the volume velocity 12.7 mm in front of the microphone, from 100$ndash;10 000 Hz. This paper presents analytical relationships between the transfer impedance and the simulated eardrum impedance. Limit of error calculations are used to derive the expected tolerances for one impedance when the tolerances are specified for the other impedance. [Work support by NIH, NINCDS.]