Nomenclature1
c |
|
|
wave speed, the speed of sound |
ex, ey, ez |
base vectors of Cartesian coordinates |
||
e |
, e |
, e |
base vectors of spherical coordinates |
bf r |
bθ |
bϕ |
circular frequency |
bfo |
b |
b |
center frequency |
flower |
|
lower limit frequency |
|
fupper |
|
upper limit frequency |
|
I |
|
|
acoustic intensity |
Ia |
|
|
moment of inertia of one particle |
IL |
|
insertion loss |
|
Ka |
|
kinetic energy of one particle |
|
kexperimentally determined coefficient of air for excess absorption coefficient
k |
wave number |
kx, ky, kz |
components of wave number vector |
Lp |
pressure level |
Lw |
pressure level from direct source |
Lx, Ly, Lz |
dimensions of a rectangular cavity |
ma |
mass of one particle |
NR |
noise reduction |
nx, ny, nz |
components of a unit vector in wave propagation direction |
PSIL |
preferred speech interference level |
Po |
averaged air pressure |
P |
absolute air pressure |
p |
pressure difference (P Po) |
p(x, t) |
one-dimensional pressure function |
p(x, y, z, t) |
three-dimensional pressure function |
1 Capital letter for amplitude and Bold facing for complex number. |
|
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 |
355 |
H. Lin et al., Lecture Notes on Acoustics and Noise Control, |
|
https://doi.org/10.1007/978-3-030-88213-6 |
|
356 |
Nomenclature |
p+() |
forward traveling pressure wave |
p () |
backward traveling pressure wave |
ps() |
standing pressure wave |
Q |
directivity of a source |
Qs |
source strength |
Qρ |
mass flow rate |
R |
room constant |
R |
reflection coefficient; radius |
Rm |
mechanical resistance |
RMS |
root mean square |
r, θ, φ |
spherical coordinates |
S |
cross-section area |
S |
surface area of a room |
SPL |
sound pressure level |
T |
period |
T(t) |
time function |
TL |
transmission loss |
T60 |
reverberation time (decay to 60 dB) |
U |
flow rate amplitude (VS) |
u |
flow rate (vS) |
V |
velocity amplitude; volume of a room |
Va |
volume occupied by one particle |
v |
flow velocity |
vca |
colliding speed of a particle |
vf(x, t) |
one-dimensional flow velocity in x-direction |
! |
flow velocity |
v f ðx, y, z, tÞ |
sound power |
w |
|
X(x) |
space function |
x, y, z |
Cartesian coordinates |
Z, Za |
acoustic impedance (p/u¼p/(vS)¼z/S) |
Zm |
mechanical impedance (pS/u¼ zS) |
z |
specific acoustic impedance (p/v) |
αsound absorption coefficient
αaverage sound absorption coefficient
α0, αtot |
total average absorption coefficient include excess absorption |
|
coefficient |
αex |
excess absorption coefficient |
γratio of specific heat
δtotal energy density
δd |
direct energy density |
δr |
reverberant energy density |
θphase angle
θca |
rotation speed of a particle |
λwave length
Nomenclature |
357 |
ξlocation along the wave number vector
ρinstantaneous mass density of the air
ρ0 |
averaged mass density of the air |
τtransmission coefficient
ϕphase angle
ωangular frequency