α
αE
A
AG
b
b(θ, ϕ)
B
BL
ℬ
ℬT
c
cg
cp
C
C‚Ñò
c‚Ñò
Cv
cV
CNEL
d
d’
D
DI
DNL
DT
e
E
Ek
Ep
EL
ℰ
ℰi
f
fr
fu, fi
F
Fe
g
G
h
H(θ, ϕ)
H(Tk)
I
Iref
I(t)
IIC
IL
ISL
‚Ñê
k
kB
kc ,km
‚Ñì
L
LA
LC
Ld
Ldn
Le
Leq
Lex
LEPN
Lh
Li
LN
Ln
LTPN
Lx
LNP
m
mr
M
ℳ
ℳℒ
ℳref
N
NCB
NEF
NL
NR
NSL
p
P
Pe
Pref
PR
Pr
PSL
PTS
q
Q
r
rt
rs
R
Re
·πò
Rm
Rr
RI
RII
RL
ROC
‚Ñõ
s
sL
S
SA, SB
SENEL
SIL
SL
SPL
SS
SSL
STC
Sv
SWR
T
TI
Tk
Tem, Tme
T‚àè
TL
TNI
TS
TSR
TTS
u
U
Ue
V
VL
Vref
w
W
x
X
Xm
Xr
y
Y
z
Z
Zm
Zr
α
β
γ
δ
η
ηB
ηe
θ
Θ
κ
λ
Γ
ξ
Ξ
Π
Πi
ρ
ρ0
ρL
ρS
σ
σS
τ
ϕ
Φ
ω
ω0
ωd
ωu, ωl
Ω
Ωeff
δ(υ)
δnm
1(υ)
acceleration; absorption coefficient (dB per distance); Sabine absorptivity
random-incidence energy absorption coefficient
sound absorption
array gain
loss per bounce; decay parameter
beam pattern
magnetic field; susceptance
bottom loss
adiabatic bulk modulus
isothermal bulk modulus
speed of sound
group speed
phase speed
electrical capacitance; acoustic compliance; heat capacity
heat capacity at constant pressure
specific heat at constant pressure
heat capacity at constant volume
specific heat at constant volume
community noise equivalent level (dBA)
detection index
detectability index
directivity; dipole strength
directivity index
detected noise level
detection threshold
specific energy
total energy
kinetic energy
potential energy
echo level
time-averaged energy density
instantaneous energy density
instantaneous force; frequency (Hz)
resonance frequency
upper, lower half-power frequencies
peak force amplitude; frequency (kHz)
effective force amplitude
spectral density of a transient function; sound-speed gradient; acceleration of gravity
conductance
specific enthalpy
directional factor
population function
time-averaged acoustic intensity; current, effective current amplitude
reference acoustic intensity
instantaneous acoustic intensity
impact isolation class
intensity level
intensity spectrum level
impulse
wave number
Boltzmann’s constant
coupling coefficients
discontinuity distance
inductance
A-weighted sound level (dBA)
C-weighted sound level (dBC)
daytime average sound level (dBA)
day-night averaged sound level (dBA)
evening average sound level (dBA)
equivalent continuous sound level (dBA)
noise exposure level (dBA)
effective perceived noise level
hourly average sound level (dBA)
intensity level re 10 ‾¹² W/m²
loudness level (phon)
night average sound level (dBA)
tone-corrected perceived noise level
x-percentile-exceeded sound level (dBA, fast)
noise pollution level (dBA)
mass
radiation mass
acoustic inertance; bending moment; molecular weight; acoustic Mach number
microphone sensitivity
microphone sensitivity level
reference microphone sensitivity
loudness (sone)
balanced noise criterion curves
noise exposure forecast
noise level
noise reduction
noise spectrum level
acoustic pressure
peak acoustic pressure amplitude
effective acoustic pressure amplitude
reference effective acoustic pressure amplitude
privacy rating
Prandtl number
pressure spectrum level
permanent threshold shift
charge; source strength density; thermal energy; scaled acoustic pressure (p/p0c²)
quality factor; source strength (amplitude of volume velocity)
specific gas constant; characteristic acoustic impedance; specific acoustic resistance
transition range
skip distance
resistance (acoustic, electrical, mechanical); reflection coefficient; radius of curvature
Reynolds number
range rate
mechanical resistance
radiation resistance
intensity reflection coefficient
power reflection coefficient
reverberation level
receiver operating characteristic
universal gas constant spring constant; condensation
spring constant; condensation
apparent source level
cross-sectional area; surface area; salinity
scattering strengths per unit area
single event noise exposure level Lex (dBA)
speech interference level
source level
sound pressure level
sea state
source spectrum level
sound transmission class
scattering strength per unit volume
standing wave ratio
period of motion; temperature; tension; transmission coefficient; reverberation time
intensity transmission coefficient
temperature in kelvin
transduction coefficients
power transmission coefficient
transmission loss
traffic noise index (dBA)
target strength
target strength for reverberation
temporary threshold shift
particle speed
peak particle velocity amplitude; volume velocity
effective particle velocity amplitude
volume; voltage; effective voltage amplitude; volume displacement
voltage level; voice level (dBA)
reference effective voltage amplitude
angular frequency; bandwidth
explosive yield
specific acoustic reactance
electrical reactance
mechanical reactance
radiation reactance
transverse displacement
admittance; Young’s modulus
specific acoustic impedance
impedance (acoustic, electrical, mechanical)
mechanical impedance
radiation impedance
spatial absorption coefficient
temporal absorption coefficient; one-half the flair constant; a nonlinearity coefficient
ratio of heat capacities; attenuation coefficient; a nonlinearity coefficient
boundary layer thickness; skin depth
coefficient of shear viscosity; efficiency
coefficient of bulk viscosity
effective coefficient of viscosity
incidence angle; phase angle; grazing angle; horizontal beam width; elevation angle
phase angle of impedance
thermal conductivity; radius of gyration; transverse component of the propagation vector
wavelength
co times the eikonal; Goldberg number
longitudinal particle displacement
amplitude of ξ
time-averaged power
instantaneous power
instantaneous density (kg/m³); probability density function
equilibrium density
linear density (kg/m)
surface density (kg/m²)
Poisson’s ratio; standard deviation; extinction cross section
scattering cross section
relaxation time; pulse duration; processing time
transformation factor; phase angle; torsion angle; turns ratio; inverse turns ratio
velocity potential
angular frequency (rad/s)
natural angular frequency
damped angular frequency
upper, lower half-power angular frequencies
solid angle
effective solid angle
Dirac delta function of argument υ
Kronecker delta
Heaviside unit function of argument υ (unit step function)
