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_speedVariables
| Variable | Description | Default |
|---|---|---|
density | Medium Density(kg/m³) | 1.225 |
sound_speed | Speed 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).
- 01Z = rho * v
- 02Z = 1.225 * 343
- 03Z = 420.2 Pa·s/m (or rayl)
Frequently Asked Questions
What is acoustic impedance used for?
It predicts how much sound reflects at boundaries between media. This is essential in ultrasound imaging, architectural acoustics, and speaker design.
What is the acoustic impedance of water?
About 1.48 x 10^6 Pa·s/m, much higher than air. This mismatch is why underwater sounds are mostly reflected at the water surface.
Why is impedance matching important in ultrasound?
Coupling gel is used between the transducer and skin to minimize the impedance mismatch and maximize sound transmission into the body.
Ready to run the numbers?
Open Acoustic Impedance Calculator