1、DEUTSCHE NORM March 1997 I I Measurement and evaluation of low-frequency environmental noise DIN 45680 - ICs 17.140.01 Messung und Bewertung tieffrequenter Geruschimmissionen in der Nachbarschaft In keeping with current practice in standards published by the International Organization for Standardiz
2、ation (ISO), a comma has been used throughout as the decimal marker. Contents Page Page Foreword 1 5 Evaluation 4 5.1 Preliminary investigations 4 Introduction . 1 5.2 Evaluating the third-octave band 1 Scope 2 pressure level measurement 4 2 Normative references 2 3 Concepts . 3 6 Test report 5 Appe
3、ndix A Example of an investigation of 4 Measurement . 4 4.1 Measurands . 4 low-frequency noise . 6 4.2 Instrumentation . 4 l notes 7 4.3 Location of measurement 4 4.4 Measurement time interval . 4 Bibliography . 8 Foreword This standard has been prepared by Technical Committee Grundlagen der Schallm
4、essung/-bewertung of the Normenausschuss Akustik, Lrmminderung und Schwingungstechnik (Acoustics, Noise Control and Vibration Engineering Standards Committee) of DIN and VDI. Introduction Low-frequency noise often leads to complaints in community environments, even when criteria specified in the rel
5、evant technical rules are met l. Investigations have shown that the perception and impact of such noise deviate considerably from those of other types of noise (medium- or high-frequency, narrow-band or wide-band noise) 2. At frequencies under 20 Hz (infrasound), there is no pronounced auditory sens
6、ation because pitch is no longer perceived. Nevertheless, infrasound is not completely inaudible, contrary to popular belief. Indeed, the hearing threshold has been established as lying at frequencies as low as 1 Hz 3, 4. Noise above the hearing threshold is normally perceived as pulsation or vibrat
7、ion. Subjects report the sensation of pressure in their ears 5 and often express feelings of uneasiness or anxiety. A particular known effect of infrasound is the lowering of breathing frequency 6. Secondary effects (such as those caused by the rattling of windows, doors or glassware, or the discern
8、ible vibration of objects or parts of the building) often lead to severe discomfort. Continued on pages 2 to 8 Translation by DIN-Sprachendienst. In case of doubt, the German-language original should be consulted as the authoritative text. No pari of this translation may be reproduced without the pr
9、ior permission of hl Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany, s the exclusive right of sale for German Standards (DIN-Normen). Ref. No. DIN 45680 : 1997-0 English price group 07 Sales No. 0107 08.00 Page 2 DIN 45680 : 1997-03 Noise with frequencies rangi
10、ng from 20 Hz to about 60 Hz is audible, although pitch perception is very weak. Often fluctuations (beats) are perceived. Subjects often complain of sensations of booming, vibration or pres- sure in the head; these sensations are only slightly dependent on loudness and lead to severe discomfort in
11、the case of steady noise. As with noise in the infrasound range, noise in this range may produce secondary effects which lead to discomfort. At frequencies above 60 Hz, pitch and noise perception is normal. Noise is considered to be especially discom- forting if it has tonal components. Here, second
12、ary effects are not significant. In dwellings, low-frequency noise can lead to considerable discomfort, especially at times when there is not much other noise. Special methods are required when investigating low-frequency noise, especially as regards the location of measurement and frequency weighti
13、ng. Location of measurement Technical rules and regulations specify that measurements be performed outside the building of interest when evaluating airborne noise from sources in the immediate area. Results obtained in this manner are not influenced by sound insulation or room acoustics (cf. VDI-Ric
14、htlinie (VDI Code of practice) 2058-1). Meeting specified noise limits normally ensures sufficient protection in dwellings. For noise with a typical spectral composition and where there are closed windows of sound insulating class 1 (SSK) as in VDI-Richt- linie 2719, the exposure to noise within the
15、 building is even below the maximum values specified in this Richtlinie for sleeping and living areas (this does not apply to commercial and industrial areas). However, if the noise contains prominent components in the low-frequency range, it is not possible to reliably assess its effects inside the
16、 building when measurements are only taken outside. For one thing, there is little information as to the effect of frequencies below 1 O0 Hz on the sound insulation of external building compo- nents (acoustical requirements for buildings are not specified for frequencies lower than 1 O0 Hz). Also, r
17、eso- nance can cause increases in the sound pressure level within rooms. For this reason, indoor measurements must also be carried out when evaluating the effects of low-frequency noise l, 2. Frequency weighting Normally, noise measurements are performed using sound level meters with an A-weighting,
18、 and the compo- nents in various frequency bands are added together; in this case, the intensity of the noise is described by the A-weighted sound pressure level, LA. However, in the case of low-frequency noise, especially where there are tonal components, discomfort can be perceived even when the h
19、earing threshold is only slightly exceeded, depending on the location and time of day of the exposure. Owing to the varying dependency on frequency of the A-weighting curve and hearing thresh- olds, LA values do not indicate whether and to what extent the hearing threshold has been exceeded. Thus, a
20、lthough a pitch with a frequency of 20 Hz and a sound pressure level of 70,5 dB lies below the threshold, while a pitch with afrequency of 80 Hz and level of 42,5 dB lies significantly above it, both pitches have the same LA value of 20 dB. Therefore, to accurately describe the effects of low-freque
21、ncy noise on hearing, the one-third octave band levels must be determined and evaluated. 1 Scope This standard specifies a method for measuring and evaluating the exposure to low-frequency noise, airborne or structure-borne, in buildings. It is intended to supplement other existing standards on the
22、same subject and serves to assess low-frequency noise for the purposes of noise control. Supplement 1 to this standard covers the evaluation of noise in industrial environments. 2 Normative references This standard incorporates, by dated or undated reference, provisions from other publications. Thes
23、e norma- tive references are cited at the appropriate places in the text, and the titles of the publications are listed below. For dated references, subsequent amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision. For un
24、dated references, the latest edition of the publication referred to applies. DIN 45630-2 Normal equal-loudness contours DIN 45641 Averaging sound levels DIN 45645-1 Supplement 1 to DIN 45680 Determining noise rating levels from measured data - Part 1 : Environmental noise Measurement and evaluation
25、of low-frequency environmental noise - Guidelines for evalua- tions in industrial environments Page 3 DIN 45680 : 1997-03 DIN 45681 Determining the tonal components of noise and tone adjustments for use in noise impact evaluations*) IEC 651 : 1979 Sound level meters (including Amendment Al : 1993) I
26、EC 260 : 1995 Electroacoustics - Octave-band and fractional-octave-band filters IS0 1996-1 : 1982 Acoustics - Description and measurement of environmental noise - Part 1 : Basic quan- tities and procedures VDI-Richtlinie 271 9 Schalldmmung von Fenstern und deren Zusatzeinrichtungen (Sound insulation
27、 of windows and their components) VDI-Richtlinie 2058-1 Beurteilung von Arbeitslrm in der Nachbarschaft (Assessment of the impact of indus- trial noise on the environment) Technische Anleitung zum Schutz gegen Lrm (TA Lrm) (German Code of practice on noise control), as of 16 July 1968, BGBI. I, 1968
28、, No. 137, Supplement, pp.1-16 I) 3 Concepts 3.1 Low-frequency range For the purposes of this standard, the low-frequency range encompasses the third-octave bands which have a centre frequency from 1 O Hz to 80 Hz. In cases where the noise components within this frequency range are extremely close t
29、ogether, the range may be extended above or below by one-third octave (cf. Explanatory notes). 3.2 Low-frequency noise For the purposes of this standard, noise in which the acoustic energy is concentrated below a frequency of 90 Hz. This is normally the case if the difference between the sound press
30、ure levels L, and LA, is greater than 20 dB (cf. subclauses 4.1 and 5.1). 3.3 Sound pressure levels LAF(t) and LCF(t) The A-weighted and C-weighted sound pressure levels, respectively, for the F time weighting as in IEC 651, expressed in dB. 3.4 Third-octave band pressure level The sound pressure le
31、vel (with an F time weighting) of noise measured using third-octave band filters having centre frequencies as in DIN EN 61 260. Designated by LTerzF(t). *) 3.5 Maximum sound pressure levels LAFmax, LCFmax and LTerzFmax The maximum A-weighted, C-weighted or third-octave band pressure level determined
32、 over the measurement time interval and which can be attributed to a single event. 3.6 Equivalent continuous sound pressure levels LAeq, LCeq and LTerz,eq The equivalent continuous sound pressure levels, as in DIN 45641, for LAF(t), LCF(t) and LTerzF(t), respectively (cf. Explanatory notes). 3.7 Thi
33、rd-octave band rating level The equivalent continuous sound level as in DIN 45641 for LTerzF(t) over the rating time interval, T,. Designated by LTerz.r. 3.8 Hearing threshold level The sound pressure level for each of the values given in table 1 describing the hearing threshold curve. Des- ignated
34、by LHs. 3.9 Residual noise Ambient noise (e.g. noise emitted by traffic, machinery, wind or human activity) remaining when the noise to be rated is suppressed (as defined in IS0 1996-1). I) Obtainable from Deutsches Informationszentrum fr technische Regeln (DIT!?) of DIN, Burggrafenstr. 6, 10787 Ber
35、lin, Germany. *) Currently at draft stage. *) Translators note. In this standard, the subscript Terz refers to the one-third octave band. Page 4 DIN 45680 : 1997-03 4 Measurement 4.1 Measurands The measurand shall either be the sound pressure level LCF(t) or LAF(t). To check whether the noise to be
36、investigated is a low-frequency noise, determine LCeq and LAeq, or, for short-term noise exposure, LCFmax and LAFmax, simultaneously wherever possible. To evaluate low-frequency noise, determine LTerz,eq and LTerzFmax for third-octave bands with centre frequen- cies between 1 O Hz to 80 Hz. Where th
37、ere site conditions are sufficiently known, the lower frequency bands need not be investigated. 4.2 Instrumentation Measurements shall be performed using type 1 sound level meters as in IEC 651, with A and C frequency weightings and the F time weighting. In addition to the requirements specified in
38、IEC 651, the limits of error for the frequency weighting curves in the frequency range 1 O Hz to 20 Hz shall not exceed I3 dB. Furthermore, the frequency weighting LIN is required for measurements using third-octave band filters. Its lower cut-off frequency shall be lower than that of the third-octa
39、ve band having the lowest centre frequency. 4.3 Location of measurement The low-frequency noise under investigation shall be measured in a room intended for human occupation and which has the greatest exposure to this noise, whether airborne or structure-borne. Measurements are to be performed with
40、closed windows and doors, and the room shall have the usual furnish- ings. The characteristic location of the noise exposure shall be that at which the disturbance due to the noise is greatest and at which humans are regularly present (cf. Explanatory notes). The microphone location shall be noted i
41、n the test report. For measurement locations near walls (e.g. on couches, beds), the microphone shall be placed about 0,5 m away from the wall. 4.4 Measurement time interval The measurement time interval depends on the extent to which the noise level fluctuates at the location of measurement. Where
42、the noise is periodic, this time interval shall cover one or more representative cycles. Generally, residual noise is to be measured only if its equivalent continuous sound pressure level is expected to be at least 6 dB below that of the noise being investigated. For intermittent residual noise, the
43、 noise being investigated may be measured during the resulting pauses. 5 Evaluation 5.1 Preliminary investigations To determine whether the noise to be investigated is low-frequency noise as defined in this standard, take the difference between the LCeqand LAeq values, or that between the LCFmax and
44、 LAFmax values, measured during the measurement time interval. If this difference is greater than 20 dB, perform measurements using third- octave band filters (cf. subclause 5.2). 5.2 Evaluating the third-octave band pressure level measurement 5.2.1 Determining LTerz,r Calculate LTerz,r, expressed i
45、n dB, using the LTerz,e values determined over the measurement time interval, taking account of the relationship between the tota7 period of exposure to the noise, Te, and the rating time interval, T, as shown in equation (1). The rating time interval shall be as specified in the relevant documents
46、(e.g. DIN 45645-1, VDI-Richt- linie 2058-1, TA Lrm, etc.). 5.2.2 Checking for tonal components To check whether the noise being investigated contains a discrete tone, compare the LTerz,eq values of adjacent third-octave bands (cf. Explanatory notes). A discrete tone is deemed to be present if the di
47、fference between the level for a band and those for its adjacent bands is greater than 5 dB. A tone whose frequency lies within the transition band between two third-octave bands cannot be identified in this manner. Such tones may be present if the difference between the energetic sum of the values
48、for LTerz,eq in two adjacent third-octave bands and the corresponding level of each of the bands neighbouring these two is greater than 5 dB. However, because this condition is not a reliable indication of the presence of a discrete tone, it may only be used as a criterion if the tone is audible. Pa
49、ge 5 DIN 45680 : 1997-03 50 63 80 5.2.3 Evaluation of low-frequency noise Compare the values in table 1 for L, with the measured values for LTerz,r and LTerzFmax. Report all third-octave bands in which LTerz,r or LTerzFmax exceeds the given L, values. 40,5 33,5 28 Table 1: Hearing threshold level as a function of centre frequency Centre frequency of I Hearing threshold hird-octave band, in Hz level, Lu, in dB 10 I 95 12,5 I 87 16 I 79 20 I 71 25 I 63 31,5 I 55,5 40 I 48 NOTE 1 : The values given for frequencies of 20 Hz and higher corre
