[Artificial mastoid device for calibrating bone telephones in an extended frequency range].

The instrument described here is designed for calibration of osteal telephones in the frequency range from 0.1 to 15 kHz. In contrast with foreign units of similar intention, the "artificial mastoid" has the impedance of its operating surface sufficiently adequate to the mean mechanical impedance of the parotid region and the forehead of the man within the whole range of operating frequencies. The instrument permits audiometry in extended frequency range in cases of osteal sound conductivity.