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Assessment of sound power levels and associated measurement uncertainties of construction equipment.

Payne, R C; Simmons, D (2001) Assessment of sound power levels and associated measurement uncertainties of construction equipment. NPL Report. CMAM 65

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Abstract

In recent years a large number of European Directives have been published containing
requirements for determining the sound power levels of machines. In particular, Directive
2000/14/EC concerns machines for use outdoors and covers fifty-seven machine types and
requires that all are labeled with their sound power level and includes new noise limits for
twenty-two machine types. The sound power level on the label includes the uncertainties due
to production variation and measurement procedures. Thus, it is of prime importance that the
sound power level is accurately determined and the level of measurement uncertainty is
carefully specified. Included in this limit category are several machines used on construction
sites, for example dozers, dumpers and excavator-loaders.
The Directive is a global approach directive, which contains some detailed test codes but still
refers to ISO B- and C-type harmonized international standards that may be used by
machinery manufacturers in order to demonstrate compliance with its requirements. For
construction plant equipment the Type-B standard is ISO 3744 and the Type-C standards are
ISO 6393, ISO 6395 and ISO 4872.
The measurement procedures described in these standards determine sound power levels in
approximately hemi-anechoic conditions from measurements of sound pressure level around
the machine by carrying out a series of measurements over a hypothetical surface surrounding
the source. The surface shape required by Directive 2000/14/EC for construction plant is a
hemisphere centred on the machine and terminating on a reflecting plane. The distribution
and number of measurement positions on this enveloping hemispherical surface vary between
the various ISO standards. However, it is assumed that absolute sound power levels and
associated measurement uncertainties are the same for all measurement configurations.
Because of the requirement on the manufacturer to affix a label to each machine that displays
a guaranteed sound power level that may have to withstand some form of verification
procedure, it is important that the sound power level and measurement uncertainty is not
affected by the choice of measurement configuration.
This report describes an experimental programme, using procedures based on those described
in the ISO standards listed above, designed to assess the effect on sound power determination
and associated measurement uncertainties, of the number of measurement positions and their
distribution on the hemispherical enveloping surface.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CMAM 65
Subjects: Acoustics
Acoustics > Sound in Air
Last Modified: 02 Feb 2018 13:17
URI: http://eprintspublications.npl.co.uk/id/eprint/1951

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