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Part 8: Acoustics

Sound pressure, intensity, power

18 entries· Edition 2020FR→ About this part

8-1logarithmic frequency range

G

o c t

d e c

·octet, decimal digit

quantity given by: where and are two frequencies (iso80000-3)

8-2static pressure

8-2.1

static pressure

p_{s}

P a

k g \cdot m^{- 1} \cdot s^{- 2}

·pascal, kilogram per metre second squared

pressure (iso80000-4) in a medium when no sound wave is present

8-2.2

sound pressure

p

P a

k g \cdot m^{- 1} \cdot s^{- 2}

·pascal, kilogram per metre second squared

difference between instantaneous total pressure and static pressure (t8-2.1)

8-3sound particle displacement

8-3

sound particle displacement

δ

m

·metre

vector (iso80000-2) quantity giving the instantaneous displacement (iso80000-3) of a particle in a medium from what would be its position…

8-4sound particle velocity

8-4

sound particle velocity

u

(ν)

m \cdot s^{- 1}

·metre per second

vector (iso80000-2) quantity given by: where is sound particle displacement (t8-3) and is time (iso80000-3)

8-5sound particle acceleration

8-5

sound particle acceleration

a

m \cdot s^{- 2}

·metre per second squared

vector (iso80000-2) quantity given by: where is sound particle velocity (t8-4) and is time

8-6volume velocity, volume flow rate

8-6

volume velocity, volume flow rate

q

q_{ν}

m^{3} \cdot s^{- 1}

·cubic metre per second

surface integral of the normal component of the sound particle velocity (t8-4) over a defined surface

8-7sound energy density

8-7

sound energy density

w

\frac{J}{m^{3}}

k g \cdot m^{- 1} \cdot s^{- 2}

·joule per cubic metre, kilogram per metre second squared

quantity given by: where is mean density (iso80000-4), is the magnitude of the sound particle velocity (t8-4), is sound pressure (t8-2.2),…

8-8sound energy

8-8

sound energy

Q

J

k g \cdot m^{2} \cdot s^{- 2}

·joule, kilogram square metre per second squared

integral of sound energy density (t8-7) over a specified volume

8-9sound power

8-9

sound power

P

W

W

k g \cdot m^{2} \cdot s^{- 3}

·watt, kilogram square metre per second cubed

integral over a surface of the product of sound pressure, (t8-2.2), and the component of the particle velocity (t8-4) in the direction…

8-10sound intensity

8-10

sound intensity

I

\frac{W}{m^{2}}

k g \cdot s^{- 3}

·watt per square metre, kilogram per second cubed

vector (iso80000-2) quantity given by: where is sound pressure (t8-2.2) and is sound particle velocity (t8-4)

8-11sound exposure

8-11

sound exposure

E

P a^{2} \cdot s

k g^{2} \cdot m^{- 2} \cdot s^{- 3}

·pascal squared second, kilogram squared per square metre second cubed

time-integrated squared sound pressure (t8-2.2)

8-12characteristic impedance of a medium for longitudinal waves

8-12

characteristic impedance of a medium for longitudinal waves

Z_{c}

P a \cdot \frac{s}{m}

k g \cdot m^{- 2} \cdot s^{- 1}

·pascal second per metre, kilogram per square metre second

quotient of sound pressure (t8-2.2) and the component of the sound particle velocity (t8-4) in the direction of the wave propagation

8-13acoustic impedance

8-13

acoustic impedance

Z_{a}

P a \cdot \frac{s}{m^{3}}

k g \cdot m^{- 4} \cdot s^{- 1}

·pascal second per cubic metre, kilogram per metre to the fourth second

at a surface, quotient of the average sound pressure (t8-2.2) over that surface and the sound volume flow rate (t8-6) through that surface

8-14sound pressure level

8-14

sound pressure level

L_{p}

dB

·decibel

quantity given by: where is the root-mean-square sound pressure in the time domain and is the reference value of sound pressure

8-15sound power level

8-15

sound power level

L_{P}

L_{W}

dB

·decibel

quantity given by: where is the magnitude of the time-averaged sound power (t8-9) and is the reference value of sound power

8-16sound exposure level

8-16

sound exposure level

L_{E}

dB

·decibel

quantity given by: where is sound exposure (t8-11) and is the reference value of sound exposure

8-17reverberation time

8-17

reverberation time

T

s

·second

time duration (iso80000-3) required for the space-averaged sound energy density (t8-7) to decrease to of its initial value (i.e. for its…

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