RECOMMENDATION ITU-R BS.708 - Determination of the electro-acoustical properties of studio monitor headphones
ANNEX 1 - Specification of tolerances
ANNEX 2 - Diffuse-field frequency response of studio monitor headphones
1 General
2 Probe microphone
3 Direct method of measurement
    3.1 Test signals
    3.2 Diffuse sound field
    3.3 Test subjects
    3.4 Measurement procedure
    3.5 Determination of individual diffuse-field frequency responses
    3.6 Determination of the diffuse-field frequency response
4 Indirect method of measurement