• AS 3755-1990

    Current The latest, up-to-date edition.

    Acoustics - Measurement of airborne noise emitted by computer and business equipment

    Available format(s):  Hardcopy, PDF 1 User, PDF 3 Users, PDF 5 Users, PDF 9 Users

    Language(s):  English

    Published date:  14-05-1990

    Publisher:  Standards Australia

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    Table of Contents - (Show below) - (Hide below)

    1 - AS 3755-1990 ACOUSTICS-MEASUREMENT OF AIRBORNE NOISE EMITTED BY COMPUTER AND BUSINESS EQUIPMENT
    4 - PREFACE
    5 - CONTENTS
    6 - 0 Introduction
    6 - 1 Scope and field of application
    6 - 1.1 Scope
    6 - 1.2 Field of application
    7 - 2 Conformance
    7 - 3 References
    7 - 4 Definitions
    7 - 4.1 level of background noise:
    7 - 4.2 bystander:
    7 - 4.3 bystander position:
    7 - 4.4 computerand business equipment:
    7 - 4.5 floor-standing equipment:
    7 - 4.6 frequency range of interest:
    7 - 4.7 functional unit:
    7 - 4.8 idling mode:
    7 - 4.9 measurement surface:
    7 - 4.10 operating mode:
    7 - 4.11 operator:
    8 - 4.12 operator position:
    8 - 4.13 rack-mounted equipment:
    8 - 4.14 reference box:
    8 - 4.15 reference sound source:
    8 - 4.16 sound power level,
    8 - 4.17 sound pressure level,
    8 - 4.18 standard test table:
    8 - 4.19 sub-assembly:
    8 - 4.20 surface-average sound pressure level
    8 - 4.21 table-top equipment:
    8 - 4.22 time-average sound pressure level
    8 - 4.23 wall-mounted equipment:
    8 - 5 Method for determining sound power levels of equipment in reverberation rooms
    8 - 5.1 General
    8 - 5.2 Measurement uncertainty
    8 - 5.3 Test environment
    8 - 5.3.1 General
    9 - 5.3.2 Test room volume
    9 - 5.3.3 Level of background noise
    9 - 5.3.4 Temperature and relative humidity
    9 - 5.4 Instrumentation
    9 - 5.4.1 General
    9 - 5.4.2 Microphone and its associated cable
    9 - 5.4.3 Frequency response of the instrumentation system
    9 - 5.4.4 Reference sound source
    9 - 5.4.5 Filter characteristics
    9 - 5.4.6 Calibration
    10 - 5.5 Installation and operation of equipment - General requirements
    10 - 5.5.1 Equipment installation
    10 - 5.5.2 Input voltage and frequency
    10 - 5.5.3 Equipment operation
    11 - 5.6 Microphone and source positions
    11 - 5.6.1 Identification of discrete-frequency components and narrow bands of noise
    11 - 5.6.2 Number of microphone positions
    12 - 5.6.3 Microphone arrangement 5.6.4 Number of equipment locations
    12 - 5.7 Measurement of sound pressure levels
    12 - 5.7.1 General
    13 - 5.7.2 Measurement duration
    13 - 5.7.3 Corrections for background noise
    13 - 5.8 Measurement of the sound pressure level of the reference sound source
    13 - 5.9 Calculation of space/time-average band sound pressure levels
    14 - 5.10 Calculation of sound power levels
    14 - 5.10.1 Calculation of band sound power levels
    14 - 5.10.2 Calculation of A-weighted sound power level
    14 - 5.11 Information to be recorded
    14 - 5.11.1 Equipment being tested
    15 - 5.11.2 Acoustical environment
    15 - 5.11.3 Instrumentation
    15 - 5.11.4 Acoustical data
    15 - 5.12 Test report
    15 - 6 Method for determining sound power levels of equipment under essentially free-field conditions over a reflecting plane
    15 - 6.1 General
    15 - 6.2 Measurement uncertainty
    16 - 6.3 Test environment
    16 - 6.3.1 General
    16 - 6.3.2 Adequacy of the test environment
    16 - 6.3.3 Level of background noise
    16 - 6.3.4 Temperature and relative humidity
    16 - 6.4 Instrumentation
    16 - 6.4.1 General
    16 - 6.4.2 Microphone and its associated cable
    16 - 6.4.3 Frequency response of the instrumentation system
    17 - 6.4.4 Weighting network and filter characteristics
    17 - 6.4.5 Calibration
    17 - 6.5 Installation and operation of equipment-General requirements
    17 - 6.5.1 Equipment installation
    17 - 6.5.2 Input voltage and frequency
    17 - 6.5.3 Equipment operation
    18 - 6.6 Measurement surface and microphone positions
    18 - 6.6.1 General
    19 - 6.6.2 Microphone positions on the measurement surface
    21 - 6.6.3 Additional microphone positions on the measurement surface
    21 - 6.6.4 Reduction in the number of microphone positions
    21 - 6.7 Measurement of sound pressure levels
    21 - 6.7.1 General
    21 - 6.7.2 Measurement duration
    21 - 6.7.3 Corrections for background noise
    22 - 6.8 Corrections for unwanted reflections
    22 - 6.9 Calculation of surface-average sound pressure level
    22 - 6.9.1 Calculation of sound pressure level averaged over the measurement surface
    22 - 6.9.2 Calculation of surface-average sound pressure level
    22 - 6.10 Calculation of sound power level
    23 - 6.11 Information to be recorded
    23 - 6.11.1 Equipment being tested
    23 - 6.11.2 Acoustical environment
    23 - 6.11.3 Instrumentation
    23 - 6.11.4 Acoustical data
    23 - 6.12 Test report
    24 - 7 Method for measuring sound pressure levels at the operator and bystander positions
    24 - 7.1 General
    24 - 7.2 Measurement uncertainty
    24 - 7.3 Test environment
    24 - 7.3.1 General
    24 - 7.3.2 Adequacy of the test environment
    24 - 7.3.3 Level of background noise
    24 - 7.3.4 Temperature and relative humidity
    24 - 7.4 Instrumentation
    24 - 7.5 Installation and operation of equipment
    24 - 7.6 Microphone positions
    24 - 7.6.1 At the operator position(s)
    25 - 7.6.2 At the bystander position(s)
    25 - 7.6.3 Microphone orientation
    26 - 7.7 Measurement of sound pressure levels
    26 - 7.7.1 General
    26 - 7.7.2 Measurement duration
    26 - 7.7.3 Corrections for background noise
    26 - 7.7.4 Corrections for unwanted reflections
    26 - 7.8 Calculation of the mean sound pressure level at the bystander position
    26 - 7.9 Information to be recorded
    26 - 7.9.1 Equipment being tested
    26 - 7.9.2 Acoustical environment
    26 - 7.9.3 Instrumentation
    27 - 7.9.4 Acoustical data
    27 - 7.10 Test report
    28 - Annex A - Standard test table
    29 - Annex B - Alternative measurement surfaces for sound power measurements in accordance with clause 6
    29 - B.1 Arrangement 3: Hemispherical measurement surface - 10 measurement positions
    29 - B.2 Arrangement 4: Hemispherical measurement surface - 10 measurement positions
    30 - B.3 Arrangement 5: Coaxial circular paths in parallel planes for microphone traverses in a free field over a reflecting plane
    30 - B.4 Arrangement 6: Quarter-sphere measurement surface - 5 measurement positions
    31 - Annex C - Installation and operating conditions for specific equipment categories
    31 - C.1 General
    31 - C.2 Equipment category: Typewriters
    32 - C.3 Equipment category: Printers
    33 - C.4 Equipment category: Teleprinters
    36 - C.5 Equipment category: Keyboards
    36 - C.6 Equipment category: Duplicators
    37 - C.7 Equipment category: Card readers and card punches
    38 - C.8 Equipment category: Magnetic tape storage units
    38 - C.9 Equipment category: Magnetic disk storage units
    39 - C.10 Equipment category: Visual display units
    39 - C.11 Equipment category: Electronic units
    39 - C.12 Equipment category: Microform readers
    40 - Annex D - Measurement of impulsive sound pressure levels and discrete tones at the operator position
    40 - D.1 Scope
    40 - D.2 Microphone position
    40 - D.3 Measurement of impulsive sound
    40 - D.4 Detection of prominent discrete tones
    42 - D.5 Information to be reported
    42 - D.6 Bibliography

    Abstract - (Show below) - (Hide below)

    Specifies procedures for measuring and reporting the noise emitted by computer and business equipment. The basic emission quantity is the A-weighted sound power level which may be used for comparing equipment of the same type, but from different manufacturers, or for comparing different equipment. Two methods for determining the sound power levels are specified in order to avoid undue restriction on existing facilities and experience. Identical with and reproduced from ISO 7779.

    Scope - (Show below) - (Hide below)

    This International Standard specifies procedures for measuring and reporting the noise emitted by computer and business equipment. It is based on the measurement procedures specified in ISO 3740, ISO 3741, ISO 3742, ISO 3744 and ISO 3745. The basic emission quantity is the A-weighted sound power level which may be used for comparing equipment of the same type, but from different manufacturers, or for comparing different equipment.The A-weighted sound power level is supplemented by the A-weighted sound pressure level measuredat the operator position(s) or the bystander positions. This sound pressure level is not a measurement of total occupational noise exposure of workers (noise immission).Two methods for determining the sound power levels are specified in this International Standard in order to avoid undue restriction on existing facilities and experience. The first method is based on reverberant room measurements (see ISO 3741 and ISO 3742); the second is based on measurements in an essentially free field over a reflecting plane (see ISO 3744 and ISO 3745). Either method may be used in accordance with this International Standard. They are comparable in accuracy and yield the same A-weighted sound power level within the tolerance range of the methods specified in this International Standard.Field of applicationThis International Standard is suitable for type tests and provides methods for manufacturers and testing laboratories to obtain comparable results.The method specified in clause 5 provides a comparison procedure for determining sound power levels in a reverberation room. The method specified in clause 6 provides a direct procedure for determining sound power levels using essentially free-field conditions over a reflecting plane. The method specified in clause 7 provides a procedure for measuring noise at the operator or bystander positions. The proceduresin this International Standard may be applied to equipment which radiates broad-band noise, narrow-band noise, noise which contains discrete-frequency components or impulsive noise.The methods specified in this International Standard allow the determination of noise emission levels for a unit tested individually.The sound power levels and sound pressure levels are used for noise emission declaration and comparison purposes. They are not to be considered as installation noise levels, however they may be used for installation planning.If sound power levels obtained are determined for several units of the same production series, the result can be used to determine a statistical value for that production series.

    General Product Information - (Show below) - (Hide below)

    Committee AV-007
    Document Type Standard
    Publisher Standards Australia
    Status Current

    Standards Referenced By This Book - (Show below) - (Hide below)

    AS Z41-1969 Octave, half octave and one-third octave band pass filters intended for the analysis of sound and vibrations
    AS 1217.6-1985 Acoustics - Determination of sound power levels of noise sources - Precision methods for anechoic and hemi-anechoic rooms
    AS 2533-2002 Acoustics - Preferred frequencies and band centre frequencies
    AS 3757-1990 Acoustics - Declared noise emission values of computers and business equipment
    AS 3756-1990 Acoustics - Measurement of high-frequency noise emitted by computer and business equipment
    AS 1259-1982 Sound level meters
    AS 1217.4-1985 Acoustics - Determination of sound power levels of noise sources - Engineering methods for special reverberation test room
    AS 1217.1-1985 Acoustics - Determination of sound power levels of noise sources - Guidelines for the use of basic Standards for the preparation of noise test codes
    AS 1217.5-1985 Acoustics - Determination of sound power levels of noise sources - Engineering methods for free-field conditions over a reflecting plane
    AS 1217.3-1985 Acoustics - Determination of sound power levels of noise sources - Precision methods for discrete-frequency and narrow-band sources in reverberation rooms
    AS 1217.2-1985 Acoustics - Determination of sound power levels of noise sources - Precision methods for broad-band sources in reverberation rooms

    Standards Referencing This Book - (Show below) - (Hide below)

    AS 62040.3-2002 Uninterruptible power systems (UPS) Method of specifying the performance and test requirements
    AS 3757-1990 Acoustics - Declared noise emission values of computers and business equipment
    AS 3756-1990 Acoustics - Measurement of high-frequency noise emitted by computer and business equipment
    AS/NZS 4577:1999 Micrographics - Readers for transparent microforms - Performance characteristics
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