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 a semi-reverberant field. Emission sound pressure level are measured as
A-weighted and, if required, C-weighted peak.
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 environment correction (subject to a specified
limiting maximum value) to be applied to the measured sound pressure levels in order
to exclude at least part of the effects of reflections from reflecting surfaces other
than the plane on which the machinery or equipment is placed. This correction is based
on the equivalent sound absorption area of the test room.
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 for the survey grade of accuracy
on the test environment and instrumentation. 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 levels 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 difference
may be even greater.
