Enter the density of the medium and the speed of sound through the medium into the calculator to determine the acoustic impedance.

Acoustic Impedance Formula

The following formula is used to calculate an acoustic impedance.

Z = p * v 
  • Where Z is the acoustic impedance
  • p is the density of the fluid
  • v is the speed of sound through the fluid

To calculate acoustic impedance, multiply the density of the medium by the speed of sound through the medium.

What is acoustic impedance?

Acoustic impedance is a fundamental concept in the study of acoustics that quantifies the resistance of a medium to the transmission of sound waves. It represents the combined effect of a material’s density and compressibility on sound propagation.

How to calculate acoustic impedance?

Example Problem:

The following example problem outlines how to calculate an acoustic impedance.

First, determine the speed of sound through the medium. In this example, the speed of sound is measured to be 1500 m/s.

Next, determine the density of the medium. In this case, the medium has a density of 500 kg/m^3.

Finally, calculate the acoustic impedance using the formula above:

Z = p * v

Z = 1500*500

Z = 750,000


What factors can affect the acoustic impedance of a medium?
Acoustic impedance is primarily affected by the density and speed of sound in the medium. However, factors such as temperature, pressure, and the medium’s physical state (solid, liquid, or gas) can also influence both the density and the speed of sound, thereby affecting the acoustic impedance.

How does acoustic impedance relate to sound reflection and transmission?
Acoustic impedance plays a crucial role in determining the amount of sound that is reflected or transmitted when it encounters a boundary between two different media. If the acoustic impedance of the two media is similar, most of the sound wave is transmitted. Conversely, if there is a significant mismatch in acoustic impedance, a larger portion of the sound wave is reflected. This principle is used in various applications, including medical ultrasound imaging and in the design of acoustically treated spaces.

Can acoustic impedance be used to identify materials or diagnose conditions?
Yes, acoustic impedance is a valuable parameter in fields such as material science and medical diagnostics. In material science, it can help identify materials based on their acoustic properties. In medical diagnostics, particularly in ultrasound imaging, differences in acoustic impedance allow the visualization of internal structures of the body by observing the reflections at tissue boundaries. This is because different tissues and materials have distinct acoustic impedances.