ISO 11819-2:2017 音響学 — 交通騒音に対する路面の影響の測定 — Part 2: 近接法 | ページ 6

3.1.1

道路区間

テスト対象の車線の総延長

3.1.2

道路区間

長さ 20 m の道路区間の一部で、その区間の実際の速度から特定の基準速度までの音圧レベルを正規化することを目的としています。

3.2.1

statistical pass-by method

SPB method

measurement procedure designed to evaluate vehicle and traffic noise generated on different sections of road surface under specific traffic conditions

Note 1 to entry: The measurements are taken from a great number of vehicles operating normally on the road. Results obtained using this procedure are normalized to standard speeds according to the category or type of road being considered. The method is specified in ISO 11819-1.

3.2.2

reference tyres

test tyres specified for the purpose of representing certain features in tyre/road sound emission, designed and constructed for use in this method with specified and reproducible standard properties

Note 1 to entry: The reference tyres are specified in ISO/TS 11819-3.

3.3.1

close-proximity level

CPX level

L_CPX

time-averaged A-weighted sound pressure level (SPL) of the tyre/road noise as determined by the CPX method, either broadband or spectral bands, as required

Note 1 to entry: The CPX level is expressed in decibels. In order to provide more information, additional suffixes are used; see Table 1.

3.3.2

CPX level for passenger cars and other light vehicles

A-weighted sound pressure level characterizing the road surface under test, which is based on the tyre/road sound pressure levels of one or more tyres representative of passenger car tyres

Note 1 to entry: The is expressed in decibels. Passenger car tyres are denoted P1, P2 … .

3.3.3

CPX level for heavy vehicles

A-weighted sound pressure level characterizing the road surface under test, which is based on the tyre/road sound pressure levels of one or more tyres representative of heavy vehicle tyres

Note 1 to entry: The is expressed in decibels. Heavy vehicle tyres are denoted H1, H2 … .

3.3.4

CPX index

index composed of the weighted average of the CPX level for passenger cars and other light vehicles ( )

Note 1 to entry: The is expressed in decibels. The method is intended to describe performance of road surfaces for a certain traffic composition in a similar way to the SPB method in ISO 11819-1, although the numerical values for a given speed are higher. More information on the calculation of CPX indices is given in Annex M.

3.3.5

acoustic variability due to road surface inhomogeneities

s_t

standard deviation of the A-weighted sound pressure levels over all segments, when using reference tyre t

Note 1 to entry: The acoustic variability is expressed in decibels. This variability is normally dominated by road surface variations, although random uncertainties could add a little. Measurement speed and wheel tracks normally do not influence this value significantly. This measure is, therefore, considered to be an indication of road surface homogeneity as far as noise properties are concerned.

3.4.1

measured speed

ν

actual speed during a measurement

Note 1 to entry: The measured speed is expressed in kilometres per hour.

3.4.2

reference speed

v_ref

preferred speed for measurement

Note 1 to entry: The reference speed is expressed in kilometres per hour. Most commonly used reference speeds are 50 km/h, 80 km/h and 110 km/h, but alternative speeds may be used if required for technical, safety or legislative reasons.

3.4.3

speed coefficient

B

coefficient determining the speed dependence of the sound pressure levels, normally used for correction of the sound pressure level to a certain reference speed

Note 1 to entry: The correction for deviations from the reference speed is given by the expression B⋅lg(v/v_ref), expressed in decibels ここで, B is dimensionless. Values of B for specific pavements are given in 11.1 d).

3.4.4

temperature coefficient

γ_t

coefficient used for correcting CPX level for the effect of temperature for tyre t

Note 1 to entry: The temperature coefficient is expressed in decibels per degree Celcius.

3.4.5

rubber hardness coefficient

β_t

coefficient used for correcting CPX level for the effect of tread rubber hardness of tyre t

Note 1 to entry: The rubber hardness coefficient is expressed in decibels per Shore A. Refer to 11.1 f) for application.

3.4.6

device-dependent correction for sound reflections

C_d,f

correction for individual measuring devices in one-third-octave bands from 315 Hz to 5 000 Hz with the centre frequency f, to account for deviations from acoustic hemi-free-field conditions

Note 1 to entry: The device correction for sound reflections is expressed in decibels. Information on the determination of C_d,f is given in A.2.