scope:

The instruments covered by this standard are designed primarily for the measurement of acoustic impedance, acoustic admittance, or both quantities, with in the human external auditory meatus. The standard is concerned with the parameters and tolerances of instruments used for measurement of aural acoustic impedance and aural acoustic admittance when the probe-tone frequency is 226 Hz. It is not within the scope of this standard to establish normative values for human ears.

Within this standard to establish normative values for human ears With this standard four types of instruments are classified according to the types of measurements that they can perform and according to their features, to-lerances, and ranges.