Acoustic impedance
Acoustic impedance Z (characteristic impedance or sound impedance) is the ratio of sound pressure p to particle velocity v. Also it is the product of the density of air ρ (rho) and the speed of sound c. See table: acoustic impedance vs. temperature.
The acoustic impedance Z in Pa·s/m (or, in the equivalent units common before the pascal was added to SI, N·s/m3) is:
: The acoustic impedance (characteristic impedance) of air is Z = 410 Pa·s/m at the temperature 25 °C (77 °F) or 413 Pa·s/m at 20 °C (68 °F). °C = degree Celsius and °F = degree Fahrenheit. p = sound pressure in N/m2 = Pa = pascal
v = particle velocity in m/s
J = sound intensity in W/m2
F = force in N = newton
ρ (rho) = density of air in kg/m3
c = speed of sound (acoustic wave velocity) in m/s
Table - Acoustic impedance Z, Speed of sound in air c,
density of air ρ vs. temperature °C
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