1、 ANSI/ASA S1.26-2014 (Revision of ANSI S1.26-1995 R2009) AMERICAN NATIONAL STANDARD Methods for Calculation of the Absorption of Sound by the Atmosphere Accredited Standards Committee S1, Acoustics Standards Secretariat Acoustical Society of America 1305 Walt Whitman Road, Suite 300 Melville, NY 117
2、47ANSI/ASAS1.26-2014 AMERICAN NATIONAL STANDARDS ON ACOUSTICS The Acoustical Society of America (ASA) provides the Secretariat for Accredited Standards Committees S1 on Acoustics, S2 on Mechanical Vibration and Shock, S3 on Bioacoustics, S3/SC 1 on Animal Bioacoustics, and S12 on Noise. These commit
3、tees have wide representation from the technical community (manufacturers, consumers, trade associations, organizations with a general interest, and government representatives). The standards are published by the Acoustical Society of America as American National Standards after approval by their re
4、spective Standards Committees and the American National Standards Institute (ANSI). These standards are developed and published as a public service to provide standards useful to the public, industry, and consumers, and to Federal, State, and local governments. Each of the Accredited Standards Commi
5、ttees (operating in accordance with procedures approved by ANSI) is responsible for developing, voting upon, and maintaining or revising its own Standards. The ASA Standards Secretariat administers Committee organization and activity and provides liaison between the Accredited Standards Committees a
6、nd ANSI. After the Standards have been produced and adopted by the Accredited Standards Committees, and approved as American National Standards by ANSI, the ASA Standards Secretariat arranges for their publication and distribution. An American National Standard implies a consensus of those substanti
7、ally concerned with its scope and provisions. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily
8、unanimity. Consensus requires that all views and objections be considered and that a concerted effort be made towards their resolution. The use of an American National Standard is completely voluntary. Their existence does not in any respect preclude anyone, whether he or she has approved the Standa
9、rds or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the Standards. NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be take
10、n periodically to reaffirm, revise, or withdraw this Standard. Acoustical Society of America ASA Secretariat 1305 Walt Whitman Road, Suite 300 Melville, New York 11747 Telephone: +1 (631) 390-0215 Fax: +1 (631) 923-2875 E-mail: asastdsacousticalsociety.org 2014 by Acoustical Society of America. This
11、 standard may not be reproduced in whole or in part in any form for sale, promotion, or any commercial purpose, or any purpose not falling within the provisions of the U.S. Copyright Act of 1976, without prior written permission of the publisher. For permission, address a request to the Standards Se
12、cretariat of the Acoustical Society of America. 2014 Acoustical Society of America All rights reserved i Contents 1 Scope 1 2 Normative references 1 3 Reference atmospheric conditions .2 3.1 Composition 2 3.2 Atmospheric pressure and temperature .2 4 Attenuation coefficients owing to atmospheric abs
13、orption for pure-tone sounds .2 4.1 Basic expression for attenuation 2 4.2 Attenuation of sound pressure levels .2 5 Calculation procedure for pure-tone attenuation coefficients .3 5.1 The variables 3 5.2 The formulae 3 5.3 Computation of attenuation coefficients .4 5.4 Tabular values of attenuation
14、 coefficients 4 6 Accuracy of calculated pure-tone attenuation coefficients for various ranges of the variables 4 6.1 Accuracy of 5 percent .4 6.2 Accuracy of 10 percent .5 6.3 Accuracy of 20 percent .5 6.4 Accuracy of 50 percent .5 7 Calculation of attenuation by atmospheric absorption for wideband
15、 sounds analyzed by fractional-octave-band filters .21 7.1 Description of the general problem and calculation methods 21 7.2 Pure-tone method to approximate band-level attenuation .22 7.3 Combined wideband and pure-tone sounds .23 8 Application to room acoustics .23 (informative) Physical mechanisms
16、 for atmospheric absorption 25 Annex AA.1 Absorption mechanisms and frequency dependence 25 A.2 Pressure dependence 26 (informative) Conversion of humidity data to molar concentration of water vapor .29 Annex BB.1 Introduction .29 B.2 Relative humidity 29 B.3 Saturation vapor pressure 29 B.4 Dewpoin
17、t .30 ii 2014 Acoustical Society of America All rights reserved (informative) Effect of inhomogeneous, real atmospheres 31 Annex CC.1 Introduction . 31 C.2 Variation with altitude . 31 C.3 Local variation 32 (informative) General spectrum-integration method for calculating the attenuation by Annex D
18、atmospheric absorption of wideband sounds analyzed by fractional-octave-band filters 35 D.1 Introduction . 35 D.2 Case 1: Band sound pressure levels known at the source 35 D.3 Case 2: Band sound pressure levels known at a receiver location 38 D.4 Case 3: Adjusting measured sound pressure levels at a
19、 receiver location for differences in attenuation by atmospheric absorption resulting from different meteorological conditions along a sound-propagation path 39 (informative) Approximate method for calculating the attenuation by atmospheric Annex Eabsorption of wideband sounds analyzed by fractional
20、-octave-band filters . 40 E.1 Introduction . 40 E.2 General approach . 40 E.3 The variables 41 E.4 The formula 41 E.5 General calculation procedure . 42 E.6 Application to stratified atmosphere . 42 E.7 Application to room acoustics . 43 Tables Table 1 Pure-tone atmospheric-absorption attenuation co
21、efficients at an air pressure of one standard atmosphere (101.325 kPa) . 6 Table C.1 Dependence of temperature Tm, pressure pm, molar concentration of water vapor hm, and pure-tone attenuation coefficient am, at mid-latitudes, on geopotential altitude H above mean sea level . 33 2014 Acoustical Soci
22、ety of America All rights reserved iii Foreword This Foreword is for information only and is not a part of the American National Standard ANSI/ASA S1.26-2014 American National Standard Methods for Calculation of the Absorption of Sound by the Atmosphere. As such, this Foreword may contain material t
23、hat has not been subjected to public review or a consensus process. In addition, it does not contain requirements necessary for conformance to the standard. This standard comprises a part of a group of definitions, standards, and specifications for use in acoustics. It was developed and approved by
24、Accredited Standards Committee S1 Acoustics, under its approved operating procedures. Those procedures have been accredited by the American National Standards Institute (ANSI). The Scope of Accredited Standards Committee S1 is as follows: Standards, specifications, methods of measurement and test, a
25、nd terminology in the field of physical acoustics, including architectural acoustics, electroacoustics, sonics and ultrasonics, and underwater sound, but excluding those aspects which pertain to biological safety, tolerances, and comfort. This standard is a revision of ANSI S1.26-1995, which has bee
26、n technically revised. The revision consists of the inclusion of wording explaining that the methods discussed will not necessarily provide similar results and updating of the normative references. This standard is the American National Standard counterpart of International Standard ISO 9613-1:1993
27、AcousticsPart 1: Calculation of the absorption of sound by the atmosphere. The technical requirements in this American National Standard are identical to those in ISO 9613-1. This standard has some additional clauses dealing with an approximate method, and includes propagation in large rooms. This s
28、tandard contains five informative annexes. Annex E in this American National Standard is not contained in ISO 9613-1. This annex describes an approximate, non-analytical method to provide a practical method to compute the atmospheric attenuation applicable to fractional-octave-band sound pressure le
29、vels measured at a large distance from a sound source or under highly absorptive conditions, or a combination of distance and absorptive conditions. Also, the scope of this American National Standard is not limited to sound propagation outdoors as is ISO 9613-1, but also includes propagation in room
30、s. At the time this Standard was submitted to Accredited Standards Committee S1, Acoustics, for approval, the membership was as follows: R.J. Peppin, Chair A. Scharine, Vice-Chair S.B. Blaeser, Secretary 3M Personal Safety Division, Detection Solutions . P.J. Battenberg M. Wurm (Alt.) Acoustical Soc
31、iety of America. R.J. Peppin . R.D. Hellweg (Alt.) Air-Conditioning, Heating and Refrigeration Institute S.J. Lind D. Abbate (Alt.) American Industrial Hygiene Association D. Driscoll D. Sandfort (Alt.) Campanella Associates . A.J. Campanella Casella USA R. Brauch iv 2014 Acoustical Society of Ameri
32、ca All rights reserved ETS-Lindgren Acoustic Systems D. Winker M. Black (Alt.) G.R.A.S. Sound FAX: +1 (631) 923-2875; E-mail: asastdsacousticalsociety.org. AMERICAN NATIONAL STANDARD ANSI/ASA S1.26-2014 Acoustical Society of America 2014 All rights reserved 1 American National Standard Methods for C
33、alculation of the Absorption of Sound by the Atmosphere 1 Scope 1.1 This Standard specifies an analytical method to calculate the attenuation of sound as a result of atmospheric absorption for a variety of meteorological conditions when the sound from any moderate-amplitude source propagates through
34、 the atmosphere. The calculation method of the Standard applies for molar concentrations of water vapor in the atmosphere from less than 0.005 percent to greater than 5 percent and for ratios of the frequency of the sound to the atmospheric pressure from as low as 4 10-4Hz/Pa (40 Hz per atmosphere)
35、to as great as 10 Hz/Pa (1 MHz per atmosphere). 1.2 For pure-tone sounds, attenuation, using descriptor “decibels,” owing to atmospheric absorption is specified by formulae in terms of an attenuation coefficient, in decibels per unit sound-propagation distance, as an analytical function of four vari
36、ables: the frequency of the sound, and the temperature, humidity, and pressure of the atmosphere. Computed attenuation coefficients are provided in tabular form for ranges of the variables commonly encountered in prediction of outdoor sound propagation. 1.3 For wideband sounds analyzed by fractional
37、-octave band filters (e.g., one-third octave band filters), an approximate method is provided for calculating the attenuation owing to atmospheric absorption from that specified for pure-tone sounds at the midband frequencies. The spectrum of the sound can be wideband with no significant discrete-fr
38、equency components or it may be a combination of wideband and discrete frequency sounds. NOTE The approximate method will not necessarily give the same results as the primary analytical method. 1.4 This Standard applies to an atmosphere with uniform meteorological conditions and to a stratified atmo
39、sphere in which the meteorological conditions may be considered to be uniform within layers. The procedures described in the Standard may be used to determine adjustments to be applied to measured sound pressure levels to account for differences between atmospheric absorption losses under different
40、meteorological conditions. The calculation method may also be applied to assess the contribution of atmospheric absorption to the decay of sound pressure level in a reverberant sound field often found in rooms. 1.5 This Standard accounts for the principal absorption mechanisms present in an atmosphe
41、re devoid of significant fog or atmospheric pollutants. It does not cover sound attenuation by mechanisms other than atmospheric absorption such as wave divergence, refraction, scattering by turbulence, ground reflection, or non-linear propagation effects. 2 Normative references The following refere
42、nced documents are indispensable for the application of this standard. For dated references, only the edition cited applies. ANSI/ASA S1.11-2014/Part 1 / IEC 61260-1:2014, American National Standard Electroacoustics - Octave-band and Fractional-octave-band Filters - Part 1: Specifications ISO 2533:1
43、975, Standard atmosphere ANSI/ASA S1.26-2014 2 2014 Acoustical Society of America All rights reserved ISO 2533:1975/Add 1:1985, Hypsometrical tables ISO 2533:1975/Add 2:1997 Extension to -5000 m and standard atmosphere as a function of altitude in feet 3 Reference atmospheric conditions 3.1 Composit
44、ion Atmospheric absorption is sensitive to the composition of the air, particularly to the varying concentration of water vapor. For clean dry air at sea level, for the purposes of this Standard, the molar concentrations, or fractional volumes, of nitrogen, oxygen, and carbon dioxide, rounded to thr
45、ee significant figures, are 0.781, 0.209, and 0.000314, respectively. For dry air, other minor trace constituents, which have no significant influence on atmospheric absorption, make up the remaining fraction. For atmospheric-absorption calculations, the standard molar concentrations of the principa
46、l constituents of dry air can be assumed to hold for altitudes to at least 50 km above mean sea level. On the other hand, the molar concentration of water vapor, which has a major influence on atmospheric absorption, varies widely near the ground and by nearly three orders of magnitude from sea leve
47、l to an altitude of 20 km. 3.2 Atmospheric pressure and temperature For purposes of this Standard, the reference atmospheric pressure, pr, is that of the International Standard Atmosphere at mean sea level, namely 101.325 kPa; see ISO 2533. The reference air temperature, Tr, is 293.15 K (i.e., +20C)
48、the temperature at which the most reliable data supporting this Standard were obtained. 4 Attenuation coefficients owing to atmospheric absorption for pure-tone sounds 4.1 Basic expression for attenuation 4.1.1 As a pure-tone sound propagates through the atmosphere over a distance s, the pressure am
49、plitude ptdecreases exponentially, as a result of the atmospheric-absorption effects described in this Standard, from its initial value piin accordance with the decay formula for plane sound waves in free space t iexp 0.1151pp s (1) where sound pressures ptand piare in pascals, distance s is in meters, a is the pure-tone sound-attenuation coefficient for atmospheric absorption in decibels per meter. From here on, for convenience, the shortened term, attenuation coefficient, will be used for in place of the full description just given. In Equati
