HOME
        TheInfoList






Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit of sound pressure is the pascal (Pa).[1]

Mathematical definition

Sound pressure diagram:
  1. silence;
  2. audible sound;
  3. atmospheric pressure;
  4. sound pressure

A sound wave in a transmission medium causes a deviation (sound pressure, a dynamic pressure) in the local ambient pressure, a static pressure.

Sound pressure, denoted p, is defined by

where

ptotal is the total pressure,
pstat is the static pressure.

Sound measurements

Sound intensity

In a sound wave, the complementary variable to sound pressure is the particle velocity. Together, they determine the sound intensity of the wave.

Sound intensity, denoted I and measured in W·m−2 in SI units, is defined by

where

p is the sound pressure,
v is the particle velocity.

Acoustic impedance

Acoustic impedance, denoted Z and measured in Pa·m−3·s in SI units, is defined by[2]

where

transmission medium causes a deviation (sound pressure, a dynamic pressure) in the local ambient pressure, a static pressure.

Sound pressure, denoted p, is defined by

where

ptotal is the total pressure,
pstat is the static pressure.

Sound measurements

Sound intensity

In a sound wave, the complementary variable to sound pressure is the particle velocity. Together, they determine the sound intensity of the wave.

Sound intensity, denoted I and measured in W·m−2 in SI units, is defined by

where

p is the sound pressure,
v is the particle velocity.

Acoustic impedance