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1、 Reference number ISO 4869-3:2007(E) ISO 2007 INTERNATIONAL STANDARD ISO 4869-3 First edition 2007-07-01 Acoustics Hearing protectors Part 3: Measurement of insertion loss of ear-muff type protectors using an acoustic test fixture Acoustique Protecteurs individuels contre le bruit Partie 3: Mesurage
2、 de laffaiblissement acoustique des protecteurs du type serre-tte au moyen dun montage dessai acoustique Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 07/16/2007 01:13:22 MDTNo repr
3、oduction or networking permitted without license from IHS -,-,- ISO 4869-3:2007(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed
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6、 is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2007 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
7、and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland
8、ii ISO 2007 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 07/16/2007 01:13:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 4869-
9、3:2007(E) ISO 2007 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member
10、 body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Elect
11、rotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopte
12、d by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
13、 rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 4869-3 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise. This first edition of ISO 4869-3 cancels and replaces ISO/TR 4869-3:1989, which has been technically revised. The t
14、echnical changes are as follows: a) the title has been changed and the standard has been revised; b) the content of the former subclause on “test signal” has been included in the subclause “Measuring system”; c) the subclause “Measuring system” no longer contains specific requirements concerning the
15、 measuring system; d) Annex B, dealing with uncertainty, has been added. ISO 4869 consists of the following parts, under the general title Acoustics Hearing protectors: Part 1: Subjective method for the measurement of sound attenuation Part 2: Estimation of effective A-weighted sound pressure levels
16、 when hearing protectors are worn Part 3: Measurement of insertion loss of ear-muff type protectors using an acoustic test fixture Part 4: Measurement of effective sound pressure levels for level-dependent sound-restoration ear-muffs Technical Report Part 5: Method for estimation of noise reduction
17、using fitting by inexperienced test subjects Technical Specification Part 6, Measurement of the active noise reduction of hearing protectors, is under preparation. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=
18、Wing, Bernie Not for Resale, 07/16/2007 01:13:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 4869-3:2007(E) iv ISO 2007 All rights reserved Introduction A Technical Report describing the use of an acoustic test fixture (ATF) to measure the insertion loss of ear- muf
19、f type protectors was published as ISO/TR 4869-3 in 1989. As testing laboratories around the world commonly use the ATF, it was decided that this Technical Report should be revised and changed into an International Standard. Compared to the original Technical Report, the most important aspect of thi
20、s part of ISO 4869 is the specification of the ATF. The ATF specified herein is not intended to supplant those dummy heads which include simulation of various anatomical features and which are used, for example, for development testing purposes. The method specified in this part of ISO 4869 does not
21、 provide results which are the same as those obtained by the subjective method, ISO 4869-1. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 07/16/2007 01:13:22 MDTNo reproduction or n
22、etworking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 4869-3:2007(E) ISO 2007 All rights reserved 1 Acoustics Hearing protectors Part 3: Measurement of insertion loss of ear-muff type protectors using an acoustic test fixture 1 Scope This part of ISO 4869 specifies a method f
23、or measuring the insertion loss of ear-muff type hearing protectors using an acoustic test fixture. The method is applicable to the investigation of production spreads of performance as part of type approval or certification procedures, and to the investigation of the change of performance with age.
24、 It is intended to ensure that ear-muff hearing protector samples submitted for subjective testing of attenuation according to ISO 4869-1 have performances typical of the type. The method specified in this part of ISO 4869 is not applicable as the basic test for type approval. Performance data obtai
25、ned by this method are not intended to be quoted as representing the real-ear sound attenuation of an ear-muff, nor the protection provided by the ear-muff. For the testing of certain ear-muffs (such as those attached to safety helmets, or those with contoured ear- cups or ear-cushions, or supra-aur
26、al ear-muffs), the procedure described in this part of ISO 4869 might need to be modified. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest editio
27、n of the referenced document (including any amendments) applies. ISO 48, Rubber, vulcanized or thermoplastic Determination of hardness (hardness between 10 IRHD and 100 IRHD) ISO 4869-1, Acoustics Hearing protectors Part 1: Subjective method for the measurement of sound attenuation ISO/IEC Guide 98:
28、1995, Guide to the expression of uncertainty in measurement (GUM) IEC 60263, Scales and sizes for plotting frequency characteristics and polar diagrams IEC 61260, Electroacoustics Octave-band and fractional-octave-band filters IEC 61094-4, Measurement microphones Part 4: Specifications for working s
29、tandard microphones Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 07/16/2007 01:13:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 4869-3:2007(E) 2
30、ISO 2007 All rights reserved 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 hearing protector device worn by a person to reduce unwanted auditory effects from acoustic stimuli 3.2 ear-muff hearing protector consisting of a supra-aural ear-cu
31、p to be pressed against each pinna or of a circumaural ear-cup to be pressed against the head around the pinna NOTE The ear-cups can be pressed against the head with a special headband or neck-band or by means of a device attached to a safety helmet or other equipment. 3.3 head-strap flexible strap
32、fitted to each cup, or to the headband close to the cup NOTE The strap can be adjusted to support the ear-muffs, usually for behind-the-head types, by resting on the top of the head. 3.4 acoustic test fixture ATF device that approximates certain dimensions of an average adult human head NOTE An ATF
33、is used for measuring the insertion loss of hearing protectors of the ear-muff type and includes a microphone for measuring sound pressure levels. 3.5 insertion loss algebraic difference, in decibels, between the one-third-octave-band sound pressure level measured by the microphone of the acoustic t
34、est fixture with the hearing protector absent and the sound pressure level with the hearing protector present 3.6 pink noise noise in which sound power spectral density is inversely proportional to frequency 3.7 acoustic isolation algebraic difference, in decibels, between the one-third-octave-band
35、sound pressure level measured by the microphone of the acoustic test fixture with a specially designed sound isolation test cup absent and the sound pressure level with the specially designed sound isolation test cup present 3.8 noise floor output level of the measurement system with the test signal
36、 switched off and a test cup providing sufficient acoustic isolation in position 3.9 reference point midpoint of a line connecting the centres of the two end faces of the acoustic test fixture Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IH
37、S Employees/1111111001, User=Wing, Bernie Not for Resale, 07/16/2007 01:13:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 4869-3:2007(E) ISO 2007 All rights reserved 3 4 Measurement principle The level of a test signal in a defined sound field is measured by a micro
38、phone located in an acoustic test fixture (ATF). The level is measured without and with the microphone being occluded by the ear-muff under test. The difference between the two measurement results is the insertion loss of the hearing protector. The ATF shall allow an ear-muff to be placed properly b
39、y positioning one ear-cup of the hearing protector over a measuring microphone. 5 Measurement of the insertion loss of ear-muffs 5.1 Acoustic test fixture (ATF) 5.1.1 General An example of an ATF is given in Figure 1. 5.1.2 Description The ATF shall be made of a non-magnetic material, for example al
40、uminium alloy or brass. It shall be in the shape of a cylinder with its axis horizontal and with (145 1) mm between the centres of the two end faces. The diameter of the cylinder shall be (135 5) mm. The angles of each of the two end faces shall be inclined towards the top at 4,5 0,5 to a vertical p
41、lane. The measuring microphone shall be of type WS1P or WS2P in accordance with IEC 61094-4. It shall be of the pressure-operated condenser type. The microphone shall be placed with its centre axis coinciding with the centre axis of the cylinder. The centre of the microphone diaphragm shall be in th
42、e plane of one of the end faces of the cylinder on the centre line. See Figure 2. To reduce structure-borne sound, the ATF shall be supported in the test sound field with a resilient mounting so as to achieve a sufficiently low noise floor. The vertical and horizontal diameters shall be marked at th
43、e end faces of the ATF, along with two or three concentric circles of suitable radius to help in positioning the ear-muff properly. The marking shall not produce any acoustical leakage. It may be necessary to equalize the static pressure under the ear-muff during fitting. This may be achieved by: a)
44、 a capillary tube that is placed between the cushion and the ATF surface during the fitting of the ear-muff to the fixture, and which is removed before the measurements; care shall be taken not to permanently deform the cushion; b) a fixed capillary tube connecting the cavity under the ear-muff to t
45、he external air; the tube shall be of diameter 0,5 mm, of length 25 mm, parallel with and near to the axis of the microphone of the acoustic test fixture, partly closed by a wire of diameter 0,4 mm and combined with a tube of diameter about 3 mm extending from the bottom of the cylinder perpendicula
46、r to the microphone axis. 5.1.3 Spacer A spacer shall project from the cylinder at right angles to the centre axis of the cylinder to support the headband of the ear-muff under test. The spacer shall be of length (123 1) mm from the centre axis of the cylinder. The free end of the spacer shall have
47、a cylindrical radius of (100 1) mm. A rubber pad (6 1) mm thick and of hardness within the range 30 IRHD to 85 IRHD (see ISO 48) shall be attached to the end of the spacer to provide slightly resilient seating for the ear-muff headband. The free face of the rubber pad shall be (50 1) mm wide and (77
48、 1) mm long. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 07/16/2007 01:13:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 4869-3:2007(E) 4 ISO 2007 All rights reserved 5.1.4 Acoustic isolation The acoustic isolation of the ATF shall be at least 50 dB for test bands with centre frequencies between 63 Hz and 250 Hz, at least 65 dB for centre fr