39.5 Measures of Noise Evaluation

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Basically, the A weighting networks are applied to obtain a measure of noise evaluation. As the measures

are legislated by governments, they are dependent on the legislative regulations and standards. In what

follows, the measure of noise evaluation legislated in Japan is given to show the concepts behind the

legislation [6].

In the regulations and standards for environmental noise problems, a variety of noise measures are

used. In order to improve these legislative regulations and standards in the future, the present

measures shall be reviewed considering the difference between noise emission and immission and the

difference between noise measurement and monitoring, and impact assessment and prediction. These

measures legislated in Japan are listed and classified in Table 39.1 by considering the difference

between noise characteristics.

TABLE 39.1 Assessment Methods Specified in Laws and Standards for Environmental Noises in Japan

Noise Sources Law and Standards Noise Indices Assessment Time

Roads Environmental Quality Standards

for Noise

LAeq,T

a Daytime (6:00 – 22:00);

nighttime (22:00 – 6:00)

Shinkansen

superexpress railways

Environmental Quality Standards

for Shinkansen Superexpress

Railways

LA,Smax

b Every event

Conventional railways Guideline of Noise Measures

for Conventional Railways

LAeq,T Daytime (7:00 – 22:00);

nighttime (22:00 – 7:00)

Aircrafts Environmental Quality Standards

for Aircrafts Noise

WECPNLc Time weighting

Guideline for the Preservation

of Living Environment

around Small Airfields

Lden

d

Construction works Noise Regulation Law

(specific noise sources)

According to

time variation:

LA

e; LA,Fmax

f;

LA5

g; LA,Fmax,5

h

Not specified;

Factories every event

Large-scale retail stores Law concerning the measures

by large scale retail stores

for preservation of living

environment

a LAeq,T, equivalent continuous A-weighted sound pressure level.

b LA,Smax, SLOW maximum value of A-weighted sound pressure level.

c WECPNL, weighted equivalent continuous perceived noise level(calculated from LA,Smax).

d Lden, day/evening/night equivalent continuous A-weighted sound pressure level.

e LA, FAST maximum value of A-weighted sound pressure level.

f LA,Fmax, A-weighted sound pressure level.

g LA5, upper value of the 90% range of A-weighted sound pressure level.

h LA,Fmax,5, upper value of the 90% range of the FAST maximum Aweighted sound pressure level.

Source: Tachibana, H. and Kaku, J. 2003. Acoustic measures for the environmental noise assessment in Japan,

pp. 3317 – 3322. In Proceedings of Inter-noise 2003 (N1007). With permission.

Noise Control Criteria and Regulations 39-5

© 2005 by Taylor & Francis Group, LLC

When considering the consistency between noise measurement and monitoring, and noise prediction

for impact assessment, it is most reasonable to use energy based indices such as LAeq. Of course, LAeq is

not a panacea and some secondary adjustment may be needed for the exact assessment of environmental

noise with different characteristics. Nevertheless, the possibility of unification by LAeq should be

considered in the near future in Japan. Although LAeq is now being widely used for the assessment of

aircraft noise in almost all countries, WECPNL is still being used in Japan. WECPNL is very close to

LAeq in concept and it is not difficult to change the assessment index from WECPNL to LAeq.

The aim of the laws and standards shown in Figure 39.2 is to measure and assess the environmental

noise for prevention or maintenance of the present situation. Therefore, any noise index should be

appropriately used for each of noise problems, as shown in Table 39.1, which presents assessment

methods specified in laws and standards for environmental noise in Japan. In particular, when

predicting the future noise situation in environmental impact assessments, the indices should be

suitable for theoretical calculation. The statistical noise indices such as the percentile level (LA5) and

maximum level (LA,Fmax or LA,Smax) specified in the laws and standards have to be predicted statistically.

It is difficult to predict these quantities by a simple physical calculation model, in principle. In this

respect, the energy-based noise indices such as LAeq can be easily treated in energy based calculation,

and the prediction model becomes simple and clear in physical meaning. In an environmental impact

assessment, the predicted results are to be compared with the related laws or standards. In the case of

road traffic noise, LAeq has been adopted in the new environmental quality standards, and therefore

prediction has become very simple in theory, founded on energy-based indices.

In the prediction of road traffic noise, a motor vehicle as the noise source can be treated as a

stationary sound sources of a constant sound power for a limited path. On the other hand, in the case

of predicting construction noise, there are many complicated problems because various kinds of

machines and equipment with various temporal variations of characteristics must be treated.

Therefore, in the construction noise prediction method given in the ”Acoustic Society of Japan

CN-model 2002” [7], various noise indices for describing the acoustic output of various types of

noise sources are specified as given in Table 39.2, which presents classification of noise sources and

indices for expressing their acoustic output. Finally, Table 39.3 presents definitions and indices of

measurement for acoustical output of noise sources.

TABLE 39.2 Classification of Noise Sources and Indices for Expressing Their Acoustic

Output

Temporal Variation Indices for Expressing

Acoustic Output

Terms

Sign

Stationary LWA A-weighted sound power level

LA(r0) A-weighted sound power level at the

reference distance (r0 ¼ 1 m)

Fluctuating randomly LWAeff Effective A-weighted sound power level

and widely LAeff(r0) Effective A-weighted sound pressure level

at the reference distance (r0 ¼ 1 m)

LA,Fmax,5(r0) 5% value of A-weighted sound pressure level

at the reference distance (r0 ¼ 1 m)

Intermittent LJA A-weighted sound energy level

impulsive LWAeff Effective A-weighted sound power level

LAE ðr0 Þ Single event sound exposure level at the

reference distance (r0 ¼ 1 m)

LA;Fmax ðr0 Þ FAST max. of A-weighted sound pressure level

at the reference distance (r0 ¼ 1 m)

Source: Tachibana, H. and Kaku, J. 2003. Acoustic measures for the environmental noise

assessment in Japan, pp. 3317 – 3322. In Proceedings of Inter-noise 2003 (N1007). With permission.

39-6 Vibration and Shock Handbook

© 2005 by Taylor & Francis Group, LLC

References

1. Fahy, F. 1985. Sound and Structural Vibration, Radiation, Transmission and Response, Academic

Press, New York, chap. 2.

2. Fields, J.M. and de Jong, R.G., Standardized general-purpose noise reaction questions for

community noise survey: research and a recommendation, J. Sound Vib., 242, 641 – 679, 2001.

3. Harris, C.M., Ed. 1979. Handbook of Noise Control, 2nd ed., McGraw-Hill, New York, chap. 37.

4. Irwin, J.D. and Graf, E.R. 1979. Industrial Noise and Vibration Control, Prentice Hall, New York,

chap. 5.

5. Lang, W.W. and Wolde, T.T. 2003. Progress report for TSG#5 ‘Global Noise Policy’, pp. 98 – 101.

In Proceedings of Inter-noise 2003 (N872).

TABLE 39.3 Definitions and Measurements of Indices for Acoustical Output of Noise Sources

Indices Definition Measurement Method

LWA LWA ¼ 10 log

PA

P0 ð1Þ

Here, P0 ¼ 1 pW

LWA ¼ LA ðrÞ þ 20 log

r

r0 þ 8 ð2Þ

Here, LA ðrÞ is the A-weighted sound pressure level

measured at a distance of r; r0 ¼ 1 m

LWAeff Effective A-weighted sound power level

applied to fluctuating, intermittent

and impulsive sounds

LWAeff ¼ LAeff ðrÞ þ 20 log

r

r0 þ 8 ð3Þ

Here, LAeff is the A-weighted sound pressure level

measured at a distance of r

LAeff ¼ 10 log

1

T

ð2

1

p2A

ðtÞ

p20

dt

" #

ð4Þ

Here, Tðt1 2 t2 Þ is averaging time (sec),

p0 ¼ 20 mPa

LJA LJA ¼ 10 log

EA

E0 ð5Þ

Here, E0 ¼ 1 pJ

LJA ¼ LAE ðrÞ þ 20 log

r

r0 þ 8 ð6Þ

Here, LAE is the single event sound exposure level

measured at a distance of r

LAE ¼ 10 log

1

T

ð2

1

p2A

ðtÞ

p20

dt

" #

ð7Þ

Here, T0 ¼ 1 sec; t1 2 t2 is the time including

the event (sec)

LA ðr0 Þ

LA;Fmaxðr0 Þ

A-weighted sound pressure level converted

to the value at the reference

distance ðr0Þ ¼ 1 m

LA ðr0Þ ¼ LA ðrÞ þ 20 log

r

r0 þ 8 ð8Þ

Here, LA ðrÞ is the A-weighted sound pressure level

measured at a distance of r

Source: Tachibana, H. and Kaku, J. 2003. Acoustic measures for the environmental noise assessment in Japan,

pp. 3317 – 3322. In Proceedings of Inter-noise 2003 (N1007). With permission.

Noise Control Criteria and Regulations 39-7

© 2005 by Taylor & Francis Group, LLC

6. Tachibana, H. and Kaku, J. 2003. Acoustic measures for the environmental noise assessment in

Japan, pp. 3317 – 3322. In Proceedings of Inter-noise 2003 (N1007).

7. Tachibana, H. and Yamamoto, K. 2003. Construction Noise Prediction Model, ASJ CN-Model 2002,

proposed by the Acoustical Society of Japan, EURONOISE, in Naples (2003.5).

8. Wolde, T.T. 2003. The European Union’s legislation on noise immission, pp. 4367 – 4371.

In Proceedings of Inter-noise 2003 (N832).

39-8 Vibration and Shock Handbook

© 2005 by Taylor & Francis Group, LLC

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