Properties of noise, sound entities

P = sound capacity in Watt (W)
p = soundpressure (N/m²)
p = 2 x 10-5 N/m² = hearing treshold
p = 10² N/m² = pain treshold
λ = wavelength in [m]
Lp = Soundpressurelevel in dB
I = Soundintensity in [W/m²]
f = Frequency in Hz
T= period, time needed for 1 wave
E = Elasticity modules in [N/m³ ] for steel 19,5 [N/m² ]
ρ = density in [kg/m³], for air at 20º = 1.21 [kg/m³] at 0º = 1,293 [kg/m³]
c = speed of sound in [m/s] at 20º c = 344 [m/s] and at 0º = 332 [m/s]
R = fixed value for gas in [j/mol . K] = 8,3 [j/mol . K]
γ = coefficient for air 1.4 (adiabatic compression/mass-volume)
t = temperature in º celcius
A = Amplitudo
v= particle speed in [m/s]
W = Energy compactness of sound in [J/m³]
ρ*c = characteristic impedance for air at 20º 415 Rayl and for water of 20º 1.48 x 10-6 Rayl

Some basic formulas:

Geonoise Thailand Co. Ltd., independent acoustical engineers Thailand.