This International Standard specifies four methods for the determination of the sound power levels of high-frequency noise emitted by computer and business equipment in the frequency range covered by the octave band centred at 16 kHz. They are complementary to the methods described in ISO 7779. The first three methods are based on the reverberation room technique described in clause 5 of ISO 7779 : 1988. The fourth method makes use of a free field over a reflecting plane as described in clause 6 of ISO 7779 : 1988. The test conditions which prescribe the installation and operation of the equipment are those specified in ISO 7779. While the four methods described in this International Standard are particularly suitable for computer and business equipment, they may also be applied to other types of equipment. This International Standard specifies methods for the determination of sound power levels in the frequency range covered by the octave band centred at 16 kHz which includes frequencies between 11,2 kHz and 22,4 kHz. NOTE — The sound power level in the 16 kHz octave band determined according to this International Standard typically is subject to a standard deviation of approximately 3 dB. A method for the measurement of high-frequency noise is in conformance with this International Standard if it satisfies all the mandatory requirements of one of the four methods described herein and if the information recorded and reported is that specified in clauses 8, 9 and 10, respectively.