1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7580 : Part 2 : 1997 I
2、mplementing Amendment No. 1, not published separately ICS 17.140.50 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Specification for The verification of sound level meters Part 2. Shortened procedure for type 2 sound level metersThis British Standard, having been prepared und
3、er the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 January 1997 BSI 04-1999 The following BSI references relate to the work on this standard: Committee reference EPL/29 Draft for comment 95/210834 DC ISBN 0 580
4、26251 0 BS 7580 : Part 2 : 1997 Issue 2, April 1999 Amendments issued since publication Amd. No. Date Text affected 10447 April 1999 Indicated by a sideline Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee EPL/29, Electroa
5、coustics, upon which the following bodies were represented: British Association of Otolaryngologists British Hearing Aid Industry Association British Medical Association British Society of Audiology British Telecommunications plc Confederation of British Industry Department of Health Department of T
6、rade and Industry (National Physical Laboratory) Health and Safety Executive Institute of Acoustics Institute of Sound and Vibration Research Institution of Electrical Engineers Medical Research Council Ministry of Defence Royal Aeronautical Society Royal National Institute for Deaf People Society o
7、f Environmental Engineers University of ExeterIssue 1, April 1999 BS 7580 : Part 2 : 1997 BSI 04-1999 a Summary of pages The following table identifies the current issue of each page. Issue 1 indicates that a page has been introduced for the first time by amendment. Subsequent issue numbers indicate
8、 an updated page. Vertical sidelining on replacement pages indicates the most recent changes (amendment, addition, deletion). Page Issue Page Issue Front cover Inside front cover a b i ii 2 2 1 blank original 2 1 2 3 4 Inside back cover Back cover 2 2 2 original original 2b blankBS 7580 : Part 2 : 1
9、997 BSI 1997 i Contents Page Foreword ii Specification 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Periodicity of verification 1 5 Verification procedure 1 6 Information to be provided 4 List of references Inside back coverii BSI 04-1999 BS 7580 : Part 2 : 1997 Issue 2, April 1999 | | | | |
10、 | Foreword This British Standard has been prepared by Technical Committee EPL/29. The tests in this Part of BS 7580 are based largely upon those in BS 7580 : Part 1 : 1997 (BS 7580 : 1992 together with Amendment No. 1 : 1997). BS 7580 Part 1 : 1997 specifies a range of tests, based on BS EN 60651 :
11、 1994 (which replaced BS 5969 : 1981) and BS EN 60804 : 1994 (formerly BS 6698 : 1986) to verify the accuracy of all types of sound level meters at regular intervals. Type 2 sound level meters are suitable for general field applications and it is considered appropriate that this type of meter be sub
12、jected to a shortened test procedure, as specified in this Part of BS 7580. The draft international standard IEC 61672 Sound level meters, when published as a BS EN standard, will replace BS EN 60651 : 1994 and BS EN 60804 : 1994. IEC 61672 specifies wider tolerances to include measurement uncertain
13、ties which were not included in BS EN 60651 and BS EN 60804. A British standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from
14、 legal obligations. BSI 04-1999 1 Issue 2, April 1999 BS 7580 : Part 2 : 1997 Specification 1 Scope This Part of BS 7580 specifies a procedure for a limited periodic verification test of Type 2 sound level meters, and includes test methods and the information to be shown on the certificate. This pro
15、cedure is intended to verify the correct operation of a limited range of features of the sound level meter. This Part of BS 7580 specifies requirements for both the calibration laboratory and the user. This Part of BS 7580 is applicable to Type 2 sound level meters originally manufactured in accorda
16、nce with BS EN 60651 and BS EN 60804, and is based largely on the tests in Part 1. It is applicable to models of sound level meter that have successfully undergone a full pattern evaluation test to BS EN 60651 : 1994 and/or BS EN 60804 : 1994 as appropriate, or to individual sound level meters that
17、have successfully undergone a full verification in accordance with BS 7580 : Part 1. The sound level meter is supplied for test together with a sound calibrator. 2 Normative references This Part of BS 7580 incorporates, by dated or undated reference, provisions from other publications. These normati
18、ve references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this Part of BS 7580 only when incorporated i
19、n the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 3 Definitions For the purposes of this standard the definitions given in BS 7580 : Part 1 : 1997 apply. 4 Periodicity of verification 4.1 General Inter
20、vals between verification to this Part of BS 7580 shall be determined by the particular application(s) of the sound level meter. NOTE. The appropriate standards or guidelines should be consulted for information on the periodicity of testing required. 4.2 Verification after repair Verification shall
21、be performed on a sound level meter after repair and before further use, if it has undergone a repair which is likely to have affected its performance. NOTE. Repairs necessitated by the failure of electronic components or transducers are likely to affect the performance of the sound level meter, whe
22、reas replacement of switches or battery leads is unlikely to have an effect. | | | | | | | | | | | | | | | 5 Verification procedure 5.1 General The calibrations of the equipment used for the verification of the sound level meter and the calibration of the sound calibrator shall be traceable to natio
23、nal standards. NOTE 1. In the UK acoustical calibration laboratories are NAMAS (National Accreditation of Measurement and Sampling) accredited through the United Kingdom Accreditation Service (UKAS); the relevant national metrology institute is the National Physical Laboratory (NPL). Where the user
24、requires testing of additional facilities covered in BS 7580 : Part 1, the test methods from BS 7580 : Part 1 shall be used. This shall be noted on the certificate. The tolerances given in this standard and in BS EN 60651 : 1994, BS EN 60804 : 1994 and BS EN 60942 : 1998 (which superseded BS 7189 :
25、1989) do not take into account any measurement uncertainty of the laboratory performing the verification. The measured values obtained during a verification shall not be extended by any measurement uncertainty when assessing whether an instrument conforms to this standard. Conformity is demonstrated
26、 when all measured values are within the specified tolerances. NOTE 2. It is recommended that the calibration certificate states, if appropriate, that verification does not accommodate measurement uncertainty. 5.2 Submission for verification The sound level meter shall be submitted for verification
27、together with its instruction manual, if required by the calibration laboratory, and the associated sound calibrator. The instruction manual shall contain all the information required by 5.2 of BS 7580 : Part 1 : 1997. In addition, information shall be supplied on the pressure to free-field correcti
28、on at the frequency of the sound calibrator for the combination of microphone/sound level meter and sound calibrator submitted. The user shall specify the span of sound levels and range settings over which the sound level meter is to be tested and whether verification is required for sound level L e
29、q or both. The level span shall be at least 40 dB, unless this is greater than the range of the sound level meter in which case it shall cover the full range of sound levels available. The level span shall include the sound pressure level of the sound calibrator submitted with the sound level meter.
30、 The specified level span shall not include any sound levels outside the manufacturers specifications given in the instruction manual. The sound level meter shall meet the pattern evaluation or verification criteria given in clause 1. NOTE. The tolerances in this Part of BS 7580 are applied followin
31、g the initial adjustment of the sound level meter using the sound calibrator supplied, and hence refer to the particular combination of sound level meter and sound calibrator. It is possible that in some cases this may mean that the meter fails to comply with the specifications, for example if the s
32、ound calibrator generates a different level to the reference level specified by the manufacturer and/or the reference range of the sound level meter is not within the user specified level span.2 BSI 04-1999 BS 7580 : Part 2 : 1997 Issue 2, April 1999 5.3 Preliminary inspection Prior to any measureme
33、nts, the sound level meter, microphone, and sound calibrator shall be visually inspected, including direct viewing of the microphone diaphragm where possible, and all controls operated to ensure that they are in working order. It shall be established that the power supply is within the operating lim
34、its specified by the manufacturer. 5.4 Sound calibrator measurements The sound calibrator supplied shall have been calibrated within the previous year, using equipment whose calibrations are traceable to national standards, and shall be supplied with a certificate. The certificate shall state the so
35、und pressure level and frequency generated by the sound calibrator when it is coupled to an appropriate model of microphone, such that manufacturers corrections are available to convert this level for free-field use with the model of microphone fitted to the sound level meter. 5.5 Setting-up The sen
36、sitivity of the sound level meter shall be checked using the sound calibrator specified in 5.2 and, if necessary, adjusted according to the sound level meter manufacturers instructions and the sound pressure level data for the sound calibrator obtained in 5.4. 5.6 Test procedure 5.6.1 General Tests
37、in 5.6 shall be performed either acoustically or by application of an electrical signal, in which case the manufacturers stated method of applying an electrical signal to the sound level meter shall be followed. NOTE 1. 4.7 of BS EN 60651 : 1994 and 4.8 of BS EN 60804 : 1994 require the manufacturer
38、 to provide the means to substitute an electrical signal for the microphone for the purpose of performing tests on the sound level meter without the microphone. The actual method of substitution will vary depending on the construction and component parts of the sound level meter. The three most impo
39、rtant situations are as follows. a) Where the sound level meter is fitted with a detachable condenser or piezoelectric microphone, the microphone should be replaced by an equivalent capacitance within a tolerance of 20 %, unless a closer tolerance is specified by the manufacturer, in series with a l
40、ow-impedance electrical signal source. b) Where the preamplifier is an integral part of the microphone, the method of substitution specified by the manufacturer should be used, and corrections used to take account of preamplifier performance. c) Where access to the point of application of the electr
41、ical signal is restricted, for example when it is inside the case of the sound level meter, the manufacturers instructions should be followed on how to gain access to this point. NOTE 2. These tests should, if possible, be performed with the sound level meter set to frequency-weighting A. 5.6.2 Line
42、arity The linearity of the sound level meter shall be tested using a continuous sinusoidal signal at a frequency in the range 1000 Hz to 4000 Hz. If available, integrating meters shall be set to indicate sound pressure level for this test. Where possible, the reference point for the test shall be a
43、measurement made at the level of the sound calibrator supplied, on the level range used for the initial adjustment of the sound level meter described in 5.5; otherwise the reference point shall be within 0.5 dB of the level generated by the sound calibrator. Measurements shall be made over the user
44、specified level span at intervals of not greater than 10 dB starting from the reference point, and shall include a measurement within 5 dB of the upper limit and 5 dB of the lower limit of the user specified level span, with the range settings specified by the user. In addition, for all the specifie
45、d range settings where the indicator range is fully contained within the user specified level span, a measurement shall be made within 5 dB of the upper limit and 5 dB of the lower limit of the indicator range. At least one measurement shall be made on each measurement range setting specified by the
46、 user. The level span over which the linearity is tested, together with the measurement range(s) used shall be stated on the certificate. All deviations shall be calculated relative to the reference point and shall be within 1.0 dB within the primary indicator range and within 1.5 dB outside the pri
47、mary indicator range. For L eq indication the tolerance is 1.0 dB over the entire range. NOTE 1. For integrating sound level meters sufficient time should be allowed for the indication to settle. NOTE 2. For sound level meters where range changing is accomplished other than by switching attenuators,
48、 for example where the microphone polarizing voltage is changed, manufacturers information may be required in addition to these tests to establish conformance of the sound level meter to these linearity requirements. 5.6.3 Frequency weighting Frequency weighting A shall be tested at frequencies of 1
49、25 Hz, 1000 Hz and 4000 Hz, using an appropriate measurement range of the sound level meter and the 1000 Hz signal as reference. Any corrections necessary for the frequency response of the microphone and, where appropriate, of the sound level meter case and the windshield shall be made to the meter indications. The response of the weighting network shall be as specified in tables IV and V of BS EN 60651 : 1994. NOTE. It is recommended that tests are performed at a constant A-weighted sound pressure level in the range 73 dB to 125 dB. In addition, a measurement at 1000
