Specifies the following data applicable to the calibration of bone vibrators for pure-tone bone-conduction audiometry: reference equivalent threshold force levels (RETFL), corresponding to the threshold of hearing of young otologically normal persons by bone-conduction audiometry; essential characteristics of the bone vibrator and of its method of coupling to a person under test and to the mechanical coupler; essential characteristics and datum level of the masking noise applied to the ear not under test.