ISO 17201-1:2018 音響—撮影範囲からのノイズ—パート1：測定による銃口爆風の決定 | ページ 6

3.1

sound pressure

p

difference between instantaneous total pressure and static pressure

Note 1 to entry: The sound pressure is expressed in pascals (Pa).

Note 2 to entry: Static pressure is the pressure that exists in the absence of sound waves.

Note 3 to entry: This definition applies to a medium allowing a non-zero mean flow in the atmosphere.

Note 4 to entry: This definition is technically in accordance with ISO 80000-8:— ¹ , item 8-2.2.

Note 5 to entry: For the definition of"static pressure" see ISO 80000-8:—, item 8-2.1, with the difference of allowing non-zero mean flow.

3.2

sound pressure level

L_p

ten times the logarithm to the base 10 of the ratio of the square of the root-mean-squared sound pressure, p_rms, to the square of a reference value, p₀

(1)

Note 1 to entry: The sound pressure level is expressed in decibels (dB).

Note 2 to entry: The sound pressure is expressed in pascals (Pa).

Note 3 to entry: For sound in air and other gases, the reference sound pressure is given by p₀ = 20 μPa.

Note 4 to entry: The sound pressure level can be frequency weighted and time weighted.

Note 5 to entry: This definition is technically in accordance with ISO 80000-8:—, item 8-15.

[SOURCE:ISO/TR 25417:2007, 2.2, modified — “the sound pressure, p” has been replaced with “the root-mean-squared sound pressure, p_rms”; the wording “where the reference value, p₀, is 20 μPa” has been removed; the original NOTE 1 and 2 have been removed; Note 1, 2, 3, 4 and 5 to entry have been added.]

3.3

peak sound pressure

p_peak

maximum absolute sound pressure (3.1) during a stated time interval

Note 1 to entry: The peak sound pressure is expressed in pascals (Pa).

[SOURCE:ISO/TR 25417:2007, 2.4, modified — The word “greatest” has been replaced with “maximum”; the word “certain” has been replaced with “stated”; NOTE 2 has been removed.]

3.4

peak sound pressure level

L_p,peak

ten times the logarithm to the base of 10 of the ratio of the square of the peak sound pressure, p_peak (3.3) to the square of the reference value, p₀

(2)

Note 1 to entry: The reference value is given by p₀ = 20 μPa.

Note 2 to entry: The peak sound pressure level is expressed in decibels (dB).

Note 3 to entry: Peak sound pressure should be determined with a detector as defined in IEC 61672-1; IEC 61672-2 only specifies the accuracy of a detector using C-weighting.

[SOURCE:ISO/TR 25417:2007, 2.5, modified — The wording “where the reference value, p₀, is 20 μPa” has been removed; the original NOTE has been removed; Note 1, 2 and 3 to entry have been added.]

3.5

event duration

T

stated time interval, long enough to encompass all significant sound of a stated event

Note 1 to entry: The event duration is expressed in seconds (s).

3.6

sound exposure

E_T

integral of the square of the sound pressure, p (3.1) , over a stated time interval or event duration, T (3.5) , starting at t₁ and ending at t₂

(3)

Note 1 to entry: The sound exposure is expressed in pascal-squared seconds (Pa²s).

[SOURCE:ISO/TR 25417:2007, 2.6, modified — The original NOTE 1 to 4 have been removed; Note 1 to entry has been added.]

3.7

sound exposure level

L_E,T

ten times the logarithm to the base 10 of the ratio of the sound exposure, E_T(3.6) , to a reference value, E₀

(4)

Note 1 to entry: The sound exposure level is expressed in decibels (dB).

Note 2 to entry: For sound in air and other gases, the reference value is given by E₀ = 400 μPa²s.

Note 3 to entry: This definition is technically in accordance with ISO 80000-8:—, item 8-17.

[SOURCE:ISO/TR 25417:2007, 2.7, modified — The original NOTE 1 to 3 have been removed; Note 1, 2 and 3 to entry have been added.]

3.8

source energy

Q

total sound source energy of the event

Note 1 to entry: The source energy is expressed in joules (J).

3.9

source energy level

L_Q

ten times the logarithm to the base 10 of the ratio of source energy, Q (3.8) , to the reference source energy, Q₀

(5)

Note 1 to entry: The source energy level is expressed in decibels (dB).

Note 2 to entry: The reference value is given by Q₀ = 10⁻¹² J.

3.10

angular source energy distribution

S_q (α)

acoustic energy radiated from the muzzle blast into the far field, per unit solid angle

Note 1 to entry: The acoustic energy radiated by the muzzle blast within a narrow cone centred on the direction α (3.14) is:

(6)

where

	Q	is the sound energy (3.8) ;
	Ω	is the solid angle expressed in steradians.

Note 2 to entry: The angular source energy distribution, S_q (α), is expressed in joules per steradians (J sr⁻¹).

Note 3 to entry: Rotational symmetry is assumed around the line with α = 0.

3.11

interpolated angular source energy distribution

continuous function in α of the source energy distribution (3.10) derived by using a defined interpolation method

Note 1 to entry: The interpolated angular source energy distribution, , is expressed in joules per steradian (J sr⁻¹).

3.12

angular source energy distribution level

L_q (α)

angular source energy distribution (3.10) , given by ten times the logarithm to base 10 of the ratio of angular source energy distribution,

(7)

Note 1 to entry: The angular source energy distribution level, L_q (α), is expressed in decibels (dB).

Note 2 to entry: The reference value is given by = 10⁻¹² J sr⁻¹.

3.13

interpolated angular source energy distribution level

continuous function in α of the angular source energy distribution level,L_q (α) (3.12), derived by using a defined interpolation method

Note 1 to entry: The interpolated angular source energy distribution level is expressed in decibels (dB).

3.14

angle alpha

α

angle between the line of fire and the line from the muzzle to the receiver

Note 1 to entry: The angle alpha is expressed in radians in all formulae.

3.15

angle beta

β

angle describing the rotation around the line of fire, anticlockwise from the view of the shooter

Note 1 to entry: The angle beta is expressed in radians in all formulae.

3.16

angle gamma

γ

angle describing the inclination of the line of fire from the horizontal plane

Note 1 to entry: The angle gamma is expressed in radians in all formulae.

Note 2 to entry: See Figure 3.

3.17

angle delta

δ

angle constituted by the projection of angle α on the horizontal plane

Note 1 to entry: The angle delta is expressed in radians in all formulae.

Note 2 to entry: See Figure 3.

3.18

directivity

D(α)

difference between the angular source energy distribution level (3.12) of the source under test and the source energy distribution level of a monopole source with the same acoustic source energy

Note 1 to entry: The directivity is expressed in decibels (dB).

3.19

muzzle distance

r_m

distance measured from the muzzle to the microphone point

Note 1 to entry: The muzzle distance is expressed in metres (m).

Note 2 to entry: See Figure 3.