1、BRITISH STANDARD BS 7445-1:2003 Description and measurement of environmental noise Part 1: Guide to quantities and procedures ICS 13.140; 17.140.01 BS 7445-1:2003 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 12 December 2003 BSI 12 Decembe
2、r 2003 First published June 1991 Second edition December 2003 The following BSI reference relates to the work on this British Standard: Committee reference EH/1/3 ISBN 0 580 43032 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical C
3、ommittee EH/1, Acoustics, to Subcommittee EH/1/3, Residential and industrial noise, upon which the following bodies were represented: Association of Noise Consultants Association of Professional Clay Target Shooting Grounds BRE Building Research Establishment British Association for Shooting and Con
4、servation British Measurement and Testing Association British Metals Federation British Occupational Hygiene Society Chartered Institute of Environmental Health Directorate of Airspace Policy Electricity Association HSE Health and Safety Executive Institute of Acoustics Institute of Sound and Vibrat
5、ion Research MoD UK Defence Standardization National Rifle Association Office of the Deputy Prime Minister (ODPM) represented by BRE Open University Society of Environmental Engineers UK Steel Association University of Bradford University of Salford Amendments issued since publication Amd. No. Date
6、CommentsBS 7445-1:2003 BSI 12 December 2003 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1S c o p e 1 2 References 1 3 Definitions 1 4 Instrumentation 4 5M e a s u r e m e n t s 5 6 Information to be recorded 8 Table 1 Symbols for sound levels 4BS 7445-1:2003
7、ii BSI 12 December 2003 Foreword This part of BS 7445 has been prepared by Subcommittee EH/1/3. It supersedes BS 7445-1:1991 (dual numbered ISO 1996-1:1982), which is withdrawn. This new edition of BS 7445-1 does not reflect a full review or revision of the standard, which will be undertaken in due
8、course. The previous edition of BS 7445-1 (1991) was identical with ISO 1996-1:1982 published by the International Organization for Standardization (ISO). Following an extended period of international consultation Subcommittee 1, Noise, of ISO Technical Committee 43, Acoustics, prepared a revised ve
9、rsion of ISO 1996-1. The UK and France voted against the adoption of the revised version as an ISO standard. The main reasons given for the negative votes included the fact that few, if any, of the innovations introduced in the revised standard could be supported by existing scientific or technical
10、evidence. In addition, UK Subcommittee EH/1/3 had serious concerns over some of the definitions introduced in the revised ISO 1996-1. UK Subcommittee EH/1/3, therefore, decided to re-issue the previous version of BS 7445-1 (dual numbered ISO 1996-1) as a new edition (BS 7445-1:2003) without making a
11、ny changes to the technical content to distinguish it from the revised version of ISO 1996-1 published in 2003. BS 7445 comprises the following parts: Part 1: Guide to quantities and procedures; Part 2: Guide to the acquisition of data pertinent to land use (identical with ISO 1996-2:1987); Part 3:
12、Guide to application to noise limits (identical with ISO 1996-3:1987). BS 7445-2 and -3 will be reviewed at such time that any revised versions of the identical ISO standards are published. This publication does not purport to include all the necessary provisions of a contract. Users are responsible
13、 for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. The BSI copyright notice dis
14、played in this document indicates when the document was last issued.BS 7445-1:2003 BSI 12 December 2003 1 Introduction Extensive research concerning the way in which human beings are affected by noise from a single kind of source such as rail or road vehicles, aircraft or industrial plants, has led
15、to a variety of measures for assessment of different kinds of noise, many of which are in common use. Conversion from one measure to another is often beset with serious uncertainty. If an acoustical environment were always dominated by a single kind of noise, the confusion caused by the existence of
16、 different measures would not be so severe. But often environmental noise is a composite of the sounds from many sources, and the distribution of the different kinds of noise is likely to change from moment to moment. The methods and procedures described in this British Standard are intended to be a
17、pplicable to sounds from all sources, individually and in combination, which contribute to the total noise at a site. At the present stage of technology this requirement seems to be best met by adopting the equivalent continuous A-weighted sound pressure level as a basic quantity. Results are always
18、 expressed in terms of this quantity even if supplemented by corrections or other descriptors that, in certain cases, may be deemed appropriate. The aim of the BS 7445 series is to provide authorities with material for the description of noise in community environments. Based on the principles descr
19、ibed in this British Standard, acceptable limits of noise can be specified and compliance with these limits can be controlled. This British Standard does not specify limits for environmental noise. 1 Scope This part of BS 7445 defines the basic quantities to be used for the description of noise in c
20、ommunity environments and describes basic procedures for the determination of these quantities. This British Standard forms the basis for further parts in the BS 7445 series. 2 References BS 5727 (ISO 3891), Method for describing aircraft noise heard on the ground ISO 3981. BS 7445-2 (ISO 1996-2), D
21、escription and measurement of environmental noise Part 2: Guide to the acquisition of data pertinent to land use. BS EN 61672-1, Electroacoustics Sound level meters Part 1: Specifications. BS EN 61672-2, Electroacoustics Sound level meters Part 2: Pattern evaluation tests. ISO 1999, Acoustics Determ
22、ination of occupational noise exposure and estimation of noise-induced hearing impairment. 3 Definitions For the purpose of this British Standard and other parts in the series the following definitions apply. 3.1 A-weighted sound pressure, in pascals root mean square sound pressure determined by use
23、 of frequency-weighting network “A” (see BS EN 61672) 3.2 sound pressure level, in decibels sound pressure level is given by the formula where p is the root mean square sound pressure, in pascals (Pa); p o is the reference sound pressure (20 4Pa) L p 10 lg p p o - 2 =BS 7445-1:2003 2 BSI 12 December
24、 2003 3.3 A-weighted sound pressure level, in decibels sound pressure level of A-weighted sound pressure is given by the formula 3.4 percentile level A-weighted sound pressure level obtained by using time-weighting “F” (see BS EN 61672) that is exceeded for N % of the time interval considered Symbol
25、: L AN,T ; for example L A95,1 his the A-weighted level exceeded for 95 % of 1 h NOTE Percentile levels as determined over a certain time interval cannot generally be extrapolated to other time intervals. 3.5 equivalent continuous A-weighted sound pressure level, in decibels value of the A-weighted
26、sound pressure level of a continuous, steady sound that, within a specified time interval T, has the same mean square sound pressure as a sound under consideration whose level varies with time, given by the formula where NOTE 1 Equivalent continuous A-weighted sound pressure level during time interv
27、al T is also called time interval average sound level, L A,T , in decibels, with the averaging time interval usually indicated in the format, for example one-hour average sound level, L A,1h . NOTE 2 Equivalent continuous A-weighted sound pressure level is also used for assessment of occupational no
28、ise exposure (see ISO 1999). 3.6 sound exposure level, in decibels sound exposure level of a discrete noise event given by the formula where NOTE L AEis given in BS 5727 (ISO 3891) as L AX(single-event exposure level). 3.7 measurement time interval that time interval over which the squared A-weighte
29、d sound pressure is integrated and averaged L Aeq,T is the equivalent continuous A-weighted sound pressure level, in decibels, determined over a time interval T starting at t 1and ending at t 2 ; p o is the reference sound pressure (20 4Pa); pA (t) is the instantaneous A-weighted sound pressure of t
30、he sound signal pA (t) is the instantaneous A-weighted sound pressure; t 2 t 1 is a stated time interval long enough to encompass all significant sound of a stated event; p o is the reference sound pressure (20 4Pa); t o is the reference duration (1 s) L pA 10 lg p A p o - 2 = L Aeq,T 10 lg 1 t 2 t
31、1 - p A 2 t () p o 2 - t 1 t 2 dt = L AE 10 lg 1 t o - p A 2 t () p o 2 - t 1 t 2 dt =BS 7445-1:2003 BSI 12 December 2003 3 3.8 reference time interval time interval to which an equivalent continuous A-weighted sound pressure level can be referred NOTE It may be specified in national or internationa
32、l standards or by local authorities to cover typical human activities and variations in the operation of sound sources. 3.9 long-term time interval specified time interval for which the results of the noise measurement are representative NOTE The long-term time interval consists of a series of refer
33、ence time intervals and is determined for the purpose of describing the environmental noise and is generally designated by competent authorities. 3.10 long-term average sound level average over the long-term time interval of the equivalent continuous A-weighted sound pressure levels for a series of
34、reference time intervals comprised within the long-term time interval, carried out as described in BS 7445-2 (ISO 1996-2) 3.11 rating level equivalent continuous A-weighted sound pressure level during a specified time interval, plus specified adjustments for tonal character and impulsiveness of the
35、sound 3.12 long-term average rating level average over the long-term time interval of the rating levels for a series of reference time intervals, carried out as described in BS 7445-2 (ISO 1996-2) 3.13 categories of noise 3.13.1 ambient noise totally encompassing sound in a given situation at a give
36、n time usually being composed of sound from many sources near and far 3.13.2 specific noise component of the ambient noise which can be specifically identified by acoustical means and may be associated with a specific source NOTE The ambient noise remaining at a given position in a given situation w
37、hen one or more specified noises are suppressed is sometimes called the residual noise. 3.13.3 initial noise ambient noise prevailing in an area before any modification of the existing situationBS 7445-1:2003 4 BSI 12 December 2003 3.14 symbols symbols for sound levels are given in Table 1 Table 1 S
38、ymbols for sound levels 4 Instrumentation 4.1 General The instrumentation system shall be designed to determine equivalent continuous A-weighted sound pressure level, either directly or indirectly, and either in direct accordance with the definition in 3.5 or by some approximative process. The instr
39、umentation shall conform to the specifications for sound level meters preferably of type 1 but at least of type 2 as given in BS EN 61672. Integrating averaging sound level meters shall be of category P as specified in BS EN 61672. Alternative instrumentation, if used, shall provide equivalent perfo
40、rmance in respect of frequency and time weightings and tolerances. The instrumentation may comprise: a) integrating-averaging sound level meter set to frequency-weighting “A”; b) sound exposure level meter for measurements of sound exposure level of discrete events; c) sound level meter set to frequ
41、ency-weighting “A” and time-weighting “S”; d) data logger for sampling the running value of A-weighted sound pressure level using time-weighting “F”; e) statistical distribution analyser for sampling the running value as in d). The instrumentation described in d) and e) could also be used to obtain
42、values of percentile levels. NOTE 1 Instrumentation of types a) and b) is preferred and will generally be used for noise of impulsive, fluctuating or cyclic character. Special care should be taken to ensure that the dynamic range is large enough and that the inherent electrical noise and overload ca
43、pacity of these instruments are suitable for the applications. NOTE 2 When using instrumentation described in e) the class interval should be chosen in relation to the overall range of sound pressure levels but should not exceed 5 dB. Ways of determining the equivalent continuous A-weighted sound pr
44、essure level using the various kinds of equipment are described in 5.4. 4.2 Calibration All equipment shall be calibrated and the configuration for calibration shall be in accordance with the manufacturers instructions. A comprehensive recalibration at certain time intervals (for example annually) m
45、ay be prescribed by authorities responsible for the use of the measurement results. A field check shall be made by the user at least before and after each series of measurements, preferably including an acoustic check of the microphone. Quantity Symbol Unit Remarks Sound pressure level L p dB A-weig
46、hted sound pressure level L pA dB Percentile level L AN,T dB Level exceeded for N % of time interval T Sound exposure level L AE dB For noise events Equivalent continuous A-weighted sound pressure level L Aeq,T dB Time interval shall be stated Long-term average sound level L Aeq,L T dB Time interval
47、 shall be stated Rating level L Ar,T dB Time interval shall be stated Long-term average rating level L Ar,L T dB Time interval shall be statedBS 7445-1:2003 BSI 12 December 2003 5 5 Measurements 5.1 General The results of the measurements described in this British Standard may be used for the purpos
48、es described in detail in the relevant standards. It is important that pertinent details of the measurement instrumentation, measurement procedure and conditions prevailing during the measurements are carefully recorded and kept for reference purposes. Reference to the pertinent standards shall also
49、 be given. NOTE 1 When the measured signals are recorded on magnetic tape for control and reference purposes it should be borne in mind that even with studio-quality (non-digital) recorders the dynamic range may fall short of that necessary when instrumentation of the types mentioned in 4.1a) and 4.1b) is used. NOTE 2 In some circumstances the frequency-weighting network “A” is inadequate for
