ISO 07779:2010 pdf free download – Acoustics一Measurement of airborne noise emitted by information technology and telecommunications equipment.
c) relative humidity: within the range defined by the manufacturer for the equipment, if a range is defined; for processing of paper and card media only, if no range is defined by the manufacturer, the recommended range is 40 % to 70 %.
In addition, for equipment whose sound pressure level varies with temperature, the room temperature during the measurement shall be 23 °C ± 2 °C.
For equipment whose noise emissions vary with altitude in a prescribed manner (e.g. by varying the speeds of air-moving devices), the altitude of the test room shall either be less than or equal to 500 m or the equipment shall be tested under conditions simulating its operation at an altitude less than or equal to 500 m.
NOTE This variation of speed of air-moving devices does not refer to the changing speed that is already accounted for in the correction for ambient pressure described in the Note to 8.8.1
8.4 Instrumentation
Instrumentation shall meet the requirements of ISO 11201, accuracy grade 2 (engineering method) and the
additional requirements of 7.4.
8.5 Installation and operation of equipment
Equipment shall be installed and operated in accordance with the requirements of Clause 5, except for hand- held and table-top equipment.
Hand-held equipment shall be installed so that the equipment is flat on a standard test table, with the front edge of the device aligned with the front edge of the table. Hand-held equipment may be optionally isolated from the surface by a small number of elastomenc feet, approximately 12 mm high.
Table-top equipment shall be installed centred on a standard test table, unless otherwise specified in Annex C. Any table-top equipment combination which includes a keyboard shall be installed such that the smallest rectangle in the plane of the table and encompassing the keyboard and other units is centred on the top of the standard test table or as specified in Annex C. Any table-top equipment combination which normally is operated with a detachable keyboard but which Is tested without the keyboard shall be centred on the test table as in the preceding sentence and as if the keyboard were present, unless otherwise specified in Annex C.
For optional measurement of sub-assemblies intended for use in table-top products, install the sub-assembly in the centre of a standard test table, isolated from the surface by a small number of elastomenc feet, approximately 12 mm high. For optional measurement of sub-assemblies intended for use in other enclosures or racks, install the sub-assembly as specified in 5.1.7.
8.6 Microphone positions
NOTE These requirements are in accordance with, but more specific than, those of ISO 11201, accuracy grade 2 (engineering method).
8.6.1 At the operator position(s)
One or more operator positions shall be specified for equipment which requires operator attention while in the operating mode.
For equipment which is operated from a standing position, the microphone shall be located 1,50 m ± 0,03 m above the floor [see Figure 1 a), position P1].
For equipment which is operated from a seated position, the microphone shall be located 1,20 m ± 0.03 m above the floor [see Figure 1 b) or C), position P2 or P3].
8.6.2 At the bystander positions
For equipment which does not require operator attention while in the operating mode, an operator position need not be specified. In this case, at least four bystander positions shall be selected and specified.
The bystander positions shall be at a horizontal distance of 1,00 m ± 0,03 m from the sides of the reference box and at a vertical distance of 1,50 m ± 0,03 m above the floor. The four preferred bystander positions are centred horizontally at the front, rear, right, and left sides of the reference box. If the length of any side of the reference box exceeds 2,0 m, additional bystander positions at 1,0 m intervals should be used. For wallmounted equipment or for equipment placed against the wall, the three preferred bystander positions are centred at the front, right, and left sides of the reference box.
For optional measurement of sub-assemblies intended for use in equipment which does not require operator attention while in the operating mode, install the sub-assembly in accordance with 5.1.7, define the reference box and apply the provisions of the preceding two paragraphs to define the bystander positions.