ISO 3747:2010 音響学 — 音圧を使用した騒音源の音響パワーレベルと音響エネルギーレベルの決定 — 残響環境でその場で使用するための工学/調査方法 | ページ 6

3.1

sound pressure

p

difference between instantaneous pressure and static pressure

Note 1 to entry: Adapted from ISO 80000-8:2007 ^[22] , 8-9.2.

Note 2 to entry: Sound pressure is expressed in pascals.

3.2

sound pressure level

L_p

[SOURCE: ISO/TR 25417:2007 ^[21] , 2.2]

Note 1 to entry: If specific frequency and time weightings as specified in IEC 61672-1 and/or specific frequency bands are applied, this is indicated by appropriate subscripts; e.g. L_{p A} denotes the A-weighted sound pressure level.

Note 2 to entry: This definition is technically in accordance with ISO 80000-8:2007 ^[22] , 8-22.

3.3

time-averaged sound pressure level

L_{p , T}

Note 1 to entry: In general, the subscript “ T ” is omitted since time-averaged sound pressure levels are necessarily determined over a certain measurement time interval.

Note 2 to entry: Time-averaged sound pressure levels are often A-weighted, in which case they are denoted by L_{p A, T} , which is usually abbreviated to L_{p A}.

Note 3 to entry: Adapted from ISO/TR 25417:2007 ^[21] , 2.3.

3.4

single event time-integrated sound pressure level

L_E

Note 1 to entry: This quantity can be obtained by L_{p , T} + 10 lg( T/ T₀) dB, where T₀ = 1 s.

Note 2 to entry: When used to measure sound immission, this quantity is usually called “sound exposure level” (see ISO/TR 25417:2007 ^[21] ).

3.5

measurement time interval

T

portion or a multiple of an operational period or operational cycle of the noise source under test for which the time-averaged sound pressure level is determined

Note 1 to entry: Measurement time interval is expressed in seconds.

3.6

comparison method

method by which the sound power level or sound energy level of a noise source under test is determined from a comparison of the sound pressure levels produced by the source under test with those of a reference sound source of known sound power output, when both sources are operated in the same environment

3.7

reverberant sound field

that portion of the sound field in the test room over which the influence of sound received directly from the source is negligible

3.8

reference sound source

sound source meeting specified requirements

Note 1 to entry: For the purposes of this International Standard, the requirements are those specified in ISO 6926:1999, Clause 5.

3.9

calibration position

position, well-defined relative to reflecting surfaces, in which the reference sound source has been calibrated

3.10

excess of sound pressure level at a given distance

Δ L_f

difference, at a given distance, between the sound pressure level of a sound source in a given room and the sound pressure level that would be expected in a free sound field, expressed in decibels

Note 1 to entry: This term and its definition differ from that given in ISO 14257:2001 ^[20] , 3.6, which relates to an average difference over a given distance range.

3.11

frequency range of interest

for general purposes, the frequency range of octave bands with nominal mid-band frequencies from 125 Hz to 8 000 Hz

Note 1 to entry: For special purposes, the frequency range can be extended or reduced, provided that the test environment, reference sound source, and instrument specifications are satisfactory for use over the modified frequency range. Any change to the frequency range of interest is clearly indicated in the test report. Measurements are not valid if the A-weighted levels are predominantly determined by high or low frequencies outside the frequency range of interest.

3.12

reference box

hypothetical right parallelepiped terminating on the floor of the test environment on which the noise source under test is located, that just encloses the source including all the significant sound-radiating components and any test table on which the source is mounted

3.13

measurement distance

d_m

distance from the nearest point of the reference box to a microphone position

Note 1 to entry: Measurement distance is expressed in metres.

3.14

background noise

noise from all sources other than the noise source under test

Note 1 to entry: Background noise includes contributions from airborne sound, noise from structure-borne vibration, and electrical noise in the instrumentation.

3.15

background noise correction

K₁

correction applied to the measured octave-band sound pressure levels at each microphone position to account for the influence of background noise

Note 1 to entry: Background noise correction is expressed in decibels.

Note 2 to entry: The background noise correction is frequency dependent; the correction in the case of a frequency band is denoted K_{1 f} , where f denotes the relevant mid-band frequency.

3.16

sound power

P

through a surface, product of the sound pressure, p , and the component of the particle velocity, u_n , at a point on the surface in the direction normal to the surface, integrated over that surface

[SOURCE: ISO 80000-8:2007 ^[22] , 8-16]

Note 1 to entry: Sound power is expressed in watts.

Note 2 to entry: The quantity relates to the rate per time at which airborne sound energy is radiated by a source.

3.17

sound power level

L_W

Note 1 to entry: If a specific frequency weighting as specified in IEC 61672-1 and/or specific frequency bands are applied, this should be indicated by appropriate subscripts; e.g. L_{W A} denotes the A-weighted sound power level.

Note 2 to entry: This definition is technically in accordance with ISO 80000-8:2007 ^[22] , 8-23.

[SOURCE: ISO/TR 25417:2007 ^[21] , 2.9]

3.18

sound energy

J

Note 1 to entry: Sound energy is expressed in joules.

Note 2 to entry: The quantity is particularly relevant for non-stationary, intermittent sound events.

[SOURCE: ISO/TR 25417:2007 ^[21] , 2.10]

3.19

sound energy level

L_J

Note 1 to entry: If a specific frequency weighting as specified in IEC 61672-1 and/or specific frequency bands are applied, this should be indicated by appropriate subscripts; e.g. L_{J A} denotes the A-weighted sound energy level.

[SOURCE: ISO/TR 25417:2007 ^[21] , 2.11]