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1、Erratum to American National Stqdard S12.9-1988 (ASA 76-1988) American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound. Part 1 ERRATUM On p. 3, under paragraph 5.1.7 sound exposure level, the title “sound pressure”shou1d be “sound exposure.” t Copyr
2、ight Acoustical Society of America Provided by IHS under license with ASA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 10:53:30 MDTNo reproduction or networking permitted without license from IHS -,-,- ANSI S I 2.9-1 988 (ASA 76-1 988) AMERICAN NATIONAL STANDARD QU
3、ANTITIES AND PROCEDURES FOR DESCRIPTION AND MEASURE= MENT OF ENVIRONMENTAL SOUND. PART 1 L Standards Secretariat Acoustical Society of America 335 East 45th Street New York, New York 1001 7-3483 Copyright Acoustical Society of America Provided by IHS under license with ASA Licensee=IHS Employees/111
4、1111001, User=Wing, Bernie Not for Resale, 04/18/2007 10:53:30 MDTNo reproduction or networking permitted without license from IHS -,-,- ASA S12-9 PT*1 88 m 0181440 O002571 093 m ASA STANDARDS PUBLICATION PROGRAM The Standards Program of the Acoustical Society of America i5 the responsibility of ASA
5、s Committee on Stan- dards (ASACOS) and is executed by the ASAs Standards Secretariat, headed by its Standards Manager. The ASAs Committee on Standards, in its responsibility for the overall Standards Publishing Program of the Acous- tical Society, has appointed a Steering Committee in charge of Pub
6、lishing and Planning. The Standards Man- ager, with the advice of the Standards Director and the Steering Committee of ASACOS, is charged with execu- tion of the Standards Publishing Program. The ASACOS Steering Committee is constituted as follows: A. Brenig, Standards Manager D. L. Johnson, Chairma
7、n,SI L. A. Wilber, Chairman, 53 K. M. Eldred, Chairman, ASACOS S. I. Hayek, Chairman, S2 W. Melnick, Chairman, S12 H. E. von Gierke, Vice Chairman, ASACOS MEMBERSHIP OF THE ASA COMMITTEE ON STANDARDS Executive Committee K. M. Eldred, Chairman and Standards Director Ken Eldred Engineering P. O. Box 1
8、037 Concord, Massachusetts O1 742 H. E. von Gierke, Vice Chairman Director, Biodynamics the unit symbol is dB for the level of any quantity. NOTE: Definitions, when available, are taken from appropriate American National Standards referenced in Sec. 4. 5.1 Definitions Nomenclature is given in 5.2 an
9、d mathematical de- scriptions of quantities are given in 5.3. 5.1.1 instantaneous sound pressure level: ten times the common logarithm of the square of the ratio of the in- stantaneous sound pressure to the reference pressure of 20 micropascals. Unit: decibel (dB). . ” . instantaneous sound pressure
10、: total instantaneous pressure, in a stated frequency band, at a point in the presence of a sound wave minus the atmospheric static pressure at that point. Unit: pascal (Pa). 5.1.2 peak sound pressure level: ten times the common logarithm of the square of the ratio of the peak sound pressure to the
11、reference sound pressure of 20 micro- pascals. Unit: decibel (dB). peak sound pressure: largest absolute value of the instantaneous sound pressure in a stated frequency band during a specified time interval. Unit: pascal (Pa). 5.1.3 sound pressure level: ten times the common loga- rithm of the squar
12、e of the ratio of the sound pressure to the reference sound pressure of 20 micropascals. Unit: decibel (dB). sound pressure: root mean square of the instanta- neous sound pressures in a stated frequency band and during a specified time interval, unless another time-averaging process is indicated. Un
13、it: pascal (Pa). 5.1.4 sound level: ten times the common logarithm of the square of the ratio of the frequency-weighted (and time-averaged) sound pressure to the reference sound pressure of 20 micropascals. Unit: decibel (dB). (frequency-weighted) sound pressure: root mean square of the instantaneou
14、s sound pressure which is filtered (frequency weighted) with a standard fre- quency characteristic (e.g., A or C, etc.) and expo- nential time weighted in accordance with the stan- dardized characteristics slow (S), fast (F), impulse (I) or peak, both weightings as specified in ANSI S1.4A-1985. The
15、time weighting shall be specified. The frequency weighting should be specified; other- wise, A-weighting will be understood. Unit: pascal (Pa). 5.1.5 maximum sound level: ten times the common logarithm of the square of the ratio of the maximum sound to the reference sound pressure of 20 micropas- ca
16、ls. Unit: decibel (dB). maximum sound largest frequency-weighted and exponential-time-weighted (or otherwise time-aver- aged) sound during a specified time interval. The time weighting or time averaging shall be specified. The frequency weighting should be specified; other- wise, A-weighting will be
17、 understood. Unit: pascal (Pa). 5.1.6 time-average sound level: ten times the common logarithm of the square of the ratio of time-average (frequency-weighted) sound pressure to the reference pressure of 20 micropascals. Unit: decibel (dB). NOTE: Time-average sound level is also termed equivalent-con
18、- tinuous sound level or equivalent-continuous frequency-weighted sound pressure level. Copyright Acoustical Society of America Provided by IHS under license with ASA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 10:53:30 MDTNo reproduction or networking permitted w
19、ithout license from IHS -,-,- ASA S32-9 PT*3 88 0383440 0002579 384 W ANSI S12.9-1988 3 time-average (frequency-weighted) sound pressure: (a) square root of the quotient of the time integral of frequency-weighted squared instantaneous sound pressures divided by the time period of integration in seco
20、nds; or (b) square root of the quotient of the sound expo- sure, in pascal-squared seconds, in a specified time period, divided by the time period of integration in seconds. Unit: pascal (Pa). For either 5.1.6(a) or 5.1.6(b), the time period of integration (averaging time) shall be stated. The fre-
21、quency weighting should be specified; otherwise, A- weighting will be understood. 5.1.7 sound exposure level: ten times the common log- arithm of the ratio of sound exposure to the reference sound exposure (Eo) of 400 micropascal-squared se- conds 400 Pal2 s. Unit: decibel (dB). NOTE: In a given mea
22、surement time period of T seconds, the sound exposure level (LE,.) is related to the time-average sound (pressure) level (L, ) as follows: L,. = L, + 10 Ig( TIC,), (1) where tu is the reference duration of 1 second (“lg” is the abbrevia- tion for logarithm to the base 10). sound pressure: time integ
23、ral of squared, frequency- weighted instantaneous sound pressure. The time period of integration should be specified when the sound exposure of the background noise is a signifi- cant contributor to the total sound exposure, when the data may be useful for identifying a source, or when the time peri
24、od of integration is otherwise use- ful. The frequency weighting should be specified; otherwise, A-weighting will be understood. Unit: pascal-squared second ( Pa2 s) . NOTES: ( 1 ) One pascal-squared second is called a sound exposure unit. (2) In principle, sound exposure is independent of the time
25、peri- od of integration. However, in practice, a measurement of sound ex- posure may be limited by the square of the equivalent sound pres- sure of the background noise multiplied by the time period of integration. In such a case, the time period of integration should be specified. (3) Some instrume
26、nts for measurement of sound exposure in- clude a threshold sound level below which the instrument does not accumulate contributions to the integral. If the threshold sound lev- el is above the level of the background noise, then the time period of integration need not be stated, but the threshold s
27、hould be stated. (4) For most transient sounds such as an aircraft flyby or a vehi- cle passby, etc., the A-frequency weighting is preferred. For short- duration, high-energy impulsive sounds, the C-frequency weighting is preferred, and measurements are to be made in accordance with ANSI 512.4-1986.
28、 5.1.8 measurement time period: The duration of the time period during which the time-average sound pres- sure or sound exposure is measured. Unit: seconds. 5.1.9 cumulative frequency-weighted sound exposures: (a) (total) day-night sound exposure level: ten times the common logarithm of the ratio of
29、 the (total) day-night sound exposure to the reference sound ex- posure (Eo) of 400 micropascals-squared seconds 400 (pPaI2 SI. Unit: decibel (dB). (total) day-night sound exposure: the sound expo- sure for a 24-hour calendar day calculated by add- ing the sound exposure obtained during daytime (070
30、0-2200 hours) to ten times the sound exposure obtained during nighttime (0000-0700 and 2200- 2400 hours). The frequency weighting should be stated; otherwise, the A-weighting will be under- stood. Unit: pascal-squared second ( Pa2 s). (b) (total) day-evening-night sound exposure level: ten times the
31、 common logarithm of the ratio of the (total) day-evening-night sound exposure to the ref- erence sound exposure (Eo) of 400 micropascal- squared seconds 400 SI. Unit: decibel (dB). (total) day-evening-night sound exposure: the sound exposure for a 24-hour calendar day calculat- ed by adding the sou
32、nd exposure obtained during daytime (0700-1900 hours) to three times the sound exposure obtained during evening (1900- 2200 hours), and to ten times the sound exposure obtained during nighttime (0000-0700 and 2200- 2400 hours). The frequency weighting should be stated; otherwise, A-weighting will be
33、 understood. Unit: pascal-squared second ( Pa2 s). 5.1.10 average values of cumulative sound exposures: (a) day-night average sound level: ten times the common logarithm of the square of the.ratio of the day-night average sound pressure to the reference sound pressure of 20 micropascals. Unit: decib
34、el (dB). day-night average sound pressure: square root of the quotient of (total) day-night sound exposure di- vided by 86 400 seconds (the number of seconds in a day). Unit: pascal (Pa). (b) day-evening-night average sound level (commu- nity noise equivalent level): ten times the common logarithm o
35、f the square of the ratio of the day-even- Copyright Acoustical Society of America Provided by IHS under license with ASA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 10:53:30 MDTNo reproduction or networking permitted without license from IHS -,-,- 4 AMERICAN NATI
36、ONAL STANDARD ing-night average sound pressure to the reference sound pressure of 20 micropascals. Unit: decibel (dB). dayevening-night average sound pressure: square root of the quotient of day-evening-night total sound exposure divided by 86 400 seconds (the number of seconds in a day). Unit: pasc
37、al (Pa). NOTE A (total) day-night total sound exposure of 1 pascal- squared second is called a day-night sound exposure unit and a (to- tal) day-evening-night sound exposure of 1 pascal-squared second is called 1 day-evening-night sound exposure unit. The approximate equivalence between day-night av
38、erage sound level (DNL) and day-night sound exposure or between day-evening-night average sound level (community noise equivalent level) (DENL or CNEL and day-evening-night sound exposure is given by Day-night sound exposure DNL (Pa2 s) (dB) (day-evening-night sound exposure) (DENL) 1 10 100 loo0 45
39、 55 65 75 For a DNL or DENL of 75 dB, a more precise sound exposure is 1087.7 PaZ S . 5.1.11 percentile level: sound level or time-average sound level that is exceeded for X percent of the total measurement period. The duration of the total mea- surement period shall be stated. The frequency weight-
40、 ing should be specified; otherwise, A-weighting will be understood. If sound level is used, then the time weighting shall be specified. If time-average sound lev- el is used, then the measurement time period for each sample shall be stated. Unit: decibel (dB). NOTES: ( 1) When determining a percent
41、ile level from sound level, the sampling rate should be at least two samples per exponential time constant. For fast weighting with a nominal time constant of 125 ms, the rate should equal or exceed 16 samples per second; for slow weighting with a nominal time constant of 1O00 ms, the rate should eq
42、ual or exceed 2 samples per second. (2) When determining a percentile level from time-average sound levels, the duration of the samples should be short compared with the duration of each event of interest. Similarly, when deter- mining a percentile level from sound levels, the exponential time const
43、ant should be short compared with the duration of each event of interest. Typically, the time constant or sample duration should be shorter than one-tenth the duration of each event of interest. 5.1.12 time above: the duration that the sound level or time-average sound level exceeds a corresponding
44、specified level during a specified total measurement period. If sound level is used, then the time weighting shall be specified; if time-averaging sound level is used, then the measurement time interval for each sample shall be specified. The frequency weighting should be specified; otherwise, the A
45、-weighting will be under- stood. The unit for time in the ratio shall be stated, e.g., as second(s) or minutes per hour or day. NOTES: ( 1 ) When determining a time above from sound level, the sam- pling rate should be at least two samples per exponential time con- stant. For fast weighting with a n
46、ominal time constant of 125 ms, the rate should equal or exceed 16 samples per second; for slow weighting with a nominal time constant of IO00 ms, the rate should equal or exceed 2 samples per second. (2) When determining a time above from time-average sound levels, the duration of the samples shoul
47、d be short compared with the duration of each event of interest. Similarly, when determining a time above from sound levels, the exponential time constant should be short compared with the duration of each event of interest. Typi- cally, the sample duration or time constant should be shorter than on
48、e-tenth the duration of each event of interest. 5.1.13 ambient sound: at a specified time, the all en- compassing sound associated with a given environ- ment, being usually a composite of sound from many sources at many directions, near and far, including the specific sound source(s) of interest. 5.
49、1.14 residual sound at a specified time, the all-en- compassing sound, being usually a composite of sound from many sources at many directions, near and far, remaining at a given position in a given situation when all uniquely identifiable discrete sound sources are eli- minated, rendered insignificant, or otherwise not in- cluded. NOTE: Residual sound may be approximated by the percentile sound level exce