1、BRITISH STANDARD BS EN ISO 10534-2:2001 Incorporating Amendment No. 1 to BS ISO 10534-2:1998 (renumbers the BS ISO as BS EN ISO 10534-2:2001) Acoustics Determination of sound absorption coefficient and impedance in impedance tubes Part 2: Transfer-function method The European Standard EN ISO 10534-2
2、:2001 has the status of a British Standard ICS 17.140.01 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS EN ISO 10534-2:2001 This British Standard, having been prepared under the direction of the Health and Environment Sector Committee, was published under the authority of t
3、he Standards Committee and comes into effect on 15 May 1999 BSI 11 April 2002 ISBN 0 580 32462 1 National foreword This British Standard is the official English language version of EN ISO 10534-2:2001. It is identical with ISO 10534-2:1998. The UK participation in its preparation was entrusted by Te
4、chnical Committee EH/1, Acoustics, to Subcommittee EH/1/6, Building acoustics, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publi
5、cations referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary prov
6、isions 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 legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquirie
7、s on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN ISO title page, the EN ISO foreword page,
8、 the ISO title page, pages ii to iv, pages 1 to 23 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments 13701 11 April 2002 Implementation of the European StandardEUROPEAN STANDAR
9、D NORME EUROPENNE EUROPISCHE NORM EN ISO 10534-2 June 2001 ICS 17.140.01 English version Acoustics Determination of sound absorption coefficient and impedance in impedances tubes Part 2: Transfer-function method (ISO 10534-2:1998) Acoustique Dtermination du facteur dabsorption acoustique et de limpd
10、ance des tubes dimpdance Partie 2: Mthode de la fonction de transfert (ISO 10534-2:1998) Bauakustik Bestimmung des Schallabsorptionsgrades und der Impedanz in Impedanzrohren Teil 2: Verfahren mit bertragungsfunktion (ISO 10534-2:1998) This European Standard was approved by CEN on 13 May 2001. CEN me
11、mbers are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on applica
12、tion to the Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the sam
13、e status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee f
14、or Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Management Centre: rue de Stassart, 36 B-1050 Brussels 2001 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 10534-2:2001 EEN ISO 10534-2:2001 BSI
15、11 April 2002 Foreword The text of the International Standard from Technical Committee ISO/TC 43, Acoustics, of the International Organization for Standardization (ISO) has been taken over as an European Standard by Technical Committee CEN/TC 126, Acoustic properties of building products and of buil
16、dings, the Secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 2001, and conflicting national standards shall be withdrawn at the latest by December 200
17、1. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway,
18、Portugal, Spain, Sweden, Switzerland and the United Kingdom.EN ISO 10534-2:2001 ii BSI 11 April 2002 Contents Page Foreword iii 1S c o p e 1 2 Definitions and symbols 1 3 Principle 3 4 Test equipment 3 5 Preliminary test and measurements 7 6 Test specimen mounting 8 7 Test procedure 8 8 Precision 13
19、 9 Test report 13 Annex A (normative) Preliminary measurements 14 Annex B (normative) Procedure for the one-microphone technique 19 Annex C (normative) Pressure-release termination of test sample 19 Annex D (informative) Theoretical background 20 Annex E (informative) Error sources 21 Annex F (infor
20、mative) Determination of diffuse sound absorption coefficient stof locally reacting absorbers from the results of this part of ISO 10534 23 Annex G (informative) Bibliography 23 Figure 1 Examples of typical microphone mounting 5 Figure 2 Microphone positions and distances 5 Figure 3 Example of layou
21、t for test equipment 7 Figure 4 Standard configuration (configuration I) 10 Figure 5 Configuration with microphones interchanged (configuration II) 10 Figure A.1 Tube attenuation correction 17 Figure A.2 Determination of the acoustic centre of a probe microphone 18 Descriptors: Acoustics, acoustic a
22、bsorption, sound absorbers, tests, acoustic tests, determination, sound absorption coefficient, acoustic measurements.EN ISO 10534-2:2001 BSI 11 April 2002 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies)
23、. The work of preparing International Standards is normally carried out through ISO technical committees. Each member 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
24、-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies
25、for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 10534-2 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 2, Building acoustics. ISO 10534 consists of the following parts,
26、under the general title Acoustics Determination of sound absorption coefficient and impedance in impedance tubes: Part 1: Method using standing wave ratio; Part 2: Transfer-function method. Annex A, Annex B and Annex C form an integral part of this part of ISO 10534. Annex D, Annex E, Annex F and An
27、nex G are for information only.iv blankEN ISO 10534-2:2001 BSI 11 April 2002 1 1 Scope This test method covers the use of an impedance tube, two microphone locations and a digital frequency analysis system for the determination of the sound absorption coefficient of sound absorbers for normal sound
28、incidence. It can also be applied for the determination of the acoustical surface impedance or surface admittance of sound absorbing materials. Since the impedance ratios of a sound absorptive material are related to its physical properties, such as airflow resistance, porosity, elasticity and densi
29、ty, measurements described in this test method are useful in basic research and product development. The test method is similar to the test method specified in ISO 10534-1 in that it uses an impedance tube with a sound source connected to one end and the test sample mounted in the tube at the other
30、end. However, the measurement technique is different. In this test method, plane waves are generated in a tube by a noise source, and the decomposition of the interference field is achieved by the measurement of acoustic pressures at two fixed locations using wall-mounted microphones or an in-tube t
31、raversing microphone, and subsequent calculation of the complex acoustic transfer function, the normal incidence absorption and the impedance ratios of the acoustic material. The test method is intended to provide an alternative, and generally much faster, measurement technique than that of ISO 1053
32、4-1. Compared with the measurement of the sound absorption in a reverberation room according to the method specified in ISO 354, there are some characteristic differences. The reverberation room method will (under ideal conditions) determine the sound absorption coefficient for diffuse sound inciden
33、ce, and the method can be used for testing of materials with pronounced structures in the lateral and normal directions. However, the reverberation room method requires test specimens which are rather large, so it is not convenient for research and development work, where only small samples of the a
34、bsorber are available. The impedance tube method is limited to parametric studies at normal incidence but requires samples of the test object which are of the same size as the cross-section of the impedance tube. For materials that are locally reacting, diffuse incidence sound absorption coefficient
35、s can be estimated from measurement results obtained by the impedance tube method. For transformation of the test results from the impedance tube method (normal incidence) to diffuse sound incidence, see Annex F. 2 Definitions and symbols For the purposes of this part of ISO 10534 the following defi
36、nitions apply. 2.1 sound absorption coefficient at normal incidence ratio of sound power entering the surface of the test object (without return) to the incident sound power for a plane wave at normal incidence 2.2 sound pressure reflection factor at normal incidence r complex ratio of the amplitude
37、 of the reflected wave to that of the incident wave in the reference plane for a plane wave at normal incidence 2.3 reference plane cross-section of the impedance tube for which the reflection factor r or the impedance Z or the admittance G are determined and which is usually the surface of the test
38、 object, if flat NOTE The reference plane is assumed to be at x =0 . 2.4 normal surface impedance Z ratio of the complex sound pressure p(0) to the normal component of the complex sound particle velocity v(0) at an individual frequency in the reference planeEN ISO 10534-2:2001 2 BSI 11 April 2002 2.
39、5 normal surface admittance G inverse of the normal surface impedance Z 2.6 wave number k 0 variable defined by k 0= /c 0= 2 f/c 0 NOTE In general the wave number is complex, so k 0= k 0 jk 0 2.7 complex sound pressure p Fourier transform of the temporal acoustic pressure 2.8 cross spectrum S 12 pro
40、duct p 2 p 1 *, determined from the complex sound pressures p 1and p 2at two microphone positions NOTE * means the complex conjugate. 2.9 auto spectrum S 11 product p 1 p 1 *, determined from the complex sound pressure p 1at microphone position one NOTE * means the complex conjugate. 2.10 transfer f
41、unction H 12 transfer function from microphone position one to two, defined by the complex ratio p 2 /p 1= S 12 /S 11or S 22 /S 21 , or (S 12 /S 11 )(S 22 /S 21 ) 1/2 2.11 calibration factor H c factor used to correct for amplitude and phase mismatches between the microphones NOTE See 7.5.2. where i
42、s the angular frequency; f is the frequency; c 0 is the speed of sound. where k 0 is the real component (k 0 =2 / 0 ); 0 is the wavelength; k 0 is the imaginary component which is the attenuation constant, in nepers per metre.EN ISO 10534-2:2001 BSI 11 April 2002 3 3 Principle The test sample is mou
43、nted at one end of a straight, rigid, smooth and airtight impedance tube. Plane waves are generated in the tube by a sound source (random, pseudo-random sequence, or chirp), and the sound pressures are measured at two locations near to the sample. The complex acoustic transfer function of the two mi
44、crophone signals is determined and used to compute the normal-incidence complex reflection factor (see Annex C), the normal-incidence absorption coefficient, and the impedance ratio of the test material. The quantities are determined as functions of the frequency with a frequency resolution which is
45、 determined from the sampling frequency and the record length of the digital frequency analysis system used for the measurements. The usable frequency range depends on the width of the tube and the spacing between the microphone positions. An extended frequency range may be obtained from the combina
46、tion of measurements with different widths and spacings. The measurements may be performed by employing one of two techniques: 4 Test equipment 4.1 Construction of the impedance tube The apparatus is essentially a tube with a test sample holder at one end and a sound source at the other. Microphone
47、ports are usually located at two or three locations along the wall of the tube, but variations involving a centre mounted microphone or probe microphone are possible. The impedance tube shall be straight with a uniform cross-section (diameter or cross dimension within 0,2 %) and with rigid, smooth,
48、non-porous walls without holes or slits (except for the microphone positions) in the test section. The walls shall be heavy and thick enough so that they are not excited to vibrations by the sound signal and show no vibration resonances in the working frequency range of the tube. For metal walls, a
49、thickness of about 5 % of the diameter is recommended for circular tubes. For rectangular tubes the corners shall be made rigid enough to prevent distortion of the side wall plates. It is recommended that the side wall thickness be about 10 % of the cross dimension of the tube. Tube walls made of concrete shall be sealed by a smooth adhesive finish to ensure air tightness. The same holds for tube walls made of wood; these should be reinforced and damped by an external coating of steel or le
