1 Scope and Object
1.1 Scope
1.1.1 General
This part applies to electric appliances (including their accessories or components) for household and similar use, supplied from mains or from batteries.
By similar use is understood the use in similar conditions as in households, for example in inns, coffee-houses, tea-rooms, barber, hairdresser shops, or launderettes, etc., if not otherwise specified in part 2.
This standard does not apply to:
– appliances, equipment or machines designed exclusively for industrial or professional purposes;
– appliances which are integrated parts of a building or its installations, such as equipment for air conditioning, heating and ventilating, oil burners for central heating, pumps for water supply and for sewage systems;
– separate motors or generators;
– appliances for outdoor use.
1.1.2 Types of noise
A classification of different types of noise is given in ISO 12001. The method specified in GB/T 3767 is suitable for measurements of all types of noise emitted by household appliances. The methods specified in ISO 3743-1 and ISO 3743-2 are suitable for all types of noise, except for sources of impulsive noise. This will be taken into account in the preparation of parts 2.
1.1.3 Size of the source
The method specified in GB/T 3767 is applicable to noise sources of any size. Limitations for the size of the source are given in 1.2.2 of ISO 3743-1 and ISO 3743-2. This will be taken into account in the preparation of parts 2.
1.2 Object
This standard is concerned with objective methods of engineering accuracy for determining sound power levels LW, expressed in decibels (dB) with reference to a sound power of one picowatt (1 pW), of airborne acoustical noise within the specified frequency range of interest (generally including the octave bands with centre frequencies from 125 Hz to 8 000 Hz), and for prescribed operating conditions of the appliance to be measured.
The following quantities are used:
– A-weighted sound power level, LWA; and
– octave band sound power levels.
In general, the described methods are specified for appliances without an operator present. A part 2 can specify that an operator will be present only for the (rare) cases where an appliance can only be operated, or must be fed, by an operator.
Methods for determining sound power levels with precision accuracy (grade 1 according to ISO 12001), specified for example in GB/T 6881 and GB/T 6882, are not included in this standard. They may, however, be applied if the appropriate test environment and instrumentation are available.
Notes: The noise values obtained under the described conditions of this part will not necessarily correspond with the noise experienced under the operational conditions of practical use.
For quality control during production etc., simplified methods may be appropriate. For noise reduction purposes, other measurement methods employing, for example, narrow-band analysis or intensity technics usually will have to be applied. These methods are not covered by this part.
1.3 Measurement uncertainty
The estimated values of the standard deviations of reproducibility of sound power levels determined according to this part are given in 1.4 of ISO 3743-1 and of ISO 3743-2. But for a particular family of appliances of same size with same operating conditions, the standard deviations of reproducibility may be smaller than these values. Hence, in part 2, standard deviations smaller than those listed in ISO standards may be stated if substantiation is available from the results of suitable interlaboratory tests.
IEC 704-3 gives values of standard deviations of reproducibility for several categories of appliances.
In case of discrepancies between the measurements where the results normally remain inside the foreseen standard deviation, it will be necessary to perform measurements according to the upper grade of accuracy: as described in GB/T 6881 or GB/T 6882.
2 Normative References
The following normative documents contain provisions which, through reference in this standard, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
GB/T 3241 -1998 Octave-Band and Fractional-Octave-Band Filter
GB/T 3767 -1996 Acoustics - Determination of Sound Power Levels of Noise Sources Using Sound Pressure - Engineering Method in An Essentially Free Field over A Reflecting Plane
GB/T 3785 -1983 Electric, Sonic Properties and Measuring Methods for Sound Level Meters
GB/T 4129 -1995 Acoustics - Determination of Sound Power Levels of Noise Sources - Requirements for the Performance and Calibration of Reference Sound Source
GB/T 6881 -1986 Acoustics - Determination of Sound Power Levels of Noise Sources - Precision Methods and Engineering Methods for Reverberation Rooms
Foreword I
IEC Foreword I
Introduction III
1 Scope and Object
2 Normative References
3 Terms and Definitions
4 Measurement Methods and Acoustical Environments
5 Instrumentation
6 Operation and Location of Appliances under Test
7 Measurement of Sound Pressure Levels
8 Calculation of Sound Pressure and Sound Power Levels
9 Information to be Recorded
10 Information to be Reported
Annex A (Normative) Standard Test Table
