1.1 General
This International Standard specifies a method for measuring the emission sound pressure
levels of machinery and equipment, at a work station and at other specified positions
nearby, in any environment which meets certain qualification requirements.
Emission sound pressure levels are measured as Aweighted and, if required, C-weighted
peak, and in frequency bands.
NOTE 1 The contents of this and related International Standards are summarized in table 1 of
ISO 11200:1995.
A method is given for determining a local environmental correction (the acceptable
maximum value of which is specified) to be applied to the measured sound pressure
levels to exclude the effects of reflections from reflecting surfaces other than the
plane on which the machinery or equipment is placed. This correction is based upon
the mean sound pressure level on a measurement surface, the sound pressure level measured
at a specified position, and either an environmental indicator or the equivalent absorption
area of the test room. The grade of accuracy of the measurements (engineering or survey)
depends upon the vaule of the local environmental correction.
A work station is occupied by an operator. It may be located in open space in the
room where the source operates, or in a cab fixed to the source, or in an enclosure
remote from the source. One or more specified positions may be located in the vicinity
of an attended or unattended machine. Such positions are sometimes referred to as
bystander positions.
This International Standard specifies requirements on the test environment. Instructions
are given for the installation and operation of the machine under test and for the
choice of microphone positions for the work station and for other specified positions.
The purpose of the measurements is to permit comparison of the performance of different
units of a given family of machinery or equipment, under defined environmental conditions
and standardized mounting and operating conditions. The data obtained may also be
used for the declaration and verification of emission sound pressure levels as specified
in ISO 4871.
NOTE 2 At any given position in relation to a particular machine, and for given mounting
and operating conditions, the emission sound pressure levels determined by the method
of this International Standard will in general be lower than the directly measured
sound pressure levels for the same machine in the typical workroom where it is used.
This is due to reverberation and the contributions of other machines. A method of
calculating the sound pressure lev els in the vicinity of a machine operating alone
in a workroom is given in ISO 11690‑3. Commonly observed differences are 1 dB to 5 dB, but in extreme cases the dif ference
may be even greater.