Specifies relevant test signal characteristics, requirements for free, diffuse and quasi-free sound fields, and procedures for sound field audiometry using pure tones, frequency modulated tones or other narrow-band test signals presented by one or more loudspeakers, primarily for the purpose of determining hearing threshold levels in the frequency range from 125 Hz to 12 500 Hz. The purpose is to ensure that tests of hearing give as high a degree of accuracy and reproducibility as possible.