Acoustic Impedance Calculator Formula

Understand the math behind the acoustic impedance calculator. Each variable explained with a worked example.

Formulas Used

Acoustic Impedance

impedance = density * sound_speed

Variables

VariableDescriptionDefault
densityMedium Density(kg/m³)1.225
sound_speedSpeed of Sound in Medium(m/s)343

How It Works

Acoustic Impedance

Acoustic impedance characterizes how much resistance a medium offers to the passage of sound waves.

Formula

Z = rho * v

where rho is the density of the medium and v is the speed of sound in it. When a wave crosses a boundary between media with different impedances, some energy is reflected and some is transmitted.

Worked Example

Acoustic impedance of air at sea level (rho = 1.225 kg/m³, v = 343 m/s).

density = 1.225sound_speed = 343
  1. 01Z = rho * v
  2. 02Z = 1.225 * 343
  3. 03Z = 420.2 Pa·s/m (or rayl)

Ready to run the numbers?

Open Acoustic Impedance Calculator