Acoustics and Vibration Animations

Daniel A. Russell, Graduate Program in Acoustics, The Pennsylvania State University

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The content of this page was originally posted on December 2, 2013. The interactive plot was updated on March 22, 2016.

Absorption and Attenuation of Sound in Air

Overview of Absorption

I intend to write some text explaining the general process of absorption of sound in air (viscous effects, thermal conduction effects, and molecular relaxation processes). But, in the mean time, the interactive plot below works and allows for calculation of the absorption coefficient for sound in air.

As sound waves travel through the air, the amplitude of the sound wave decreases (attenuates) as some of the energy carried by the wave is lost to friction and relaxation processes in the gas (air). There are two main processes by which sound energy is absorbed by air:

NOTE: This plot is a Computable Document Format (CDF) object created by Mathematica and you will need to install the free Wolfram CDF Player to be able to see it and interact with it. Unfortunately, the CDF player is only available for Safari and Firefox on Mac OSX and Firefox and Internet Explorer for Windows. And the CDF player is not yet available for mobile devices.

Here is a link to a standalone version of the absorption calculator (you'll still need to download the Wolfram CDF Player to interact with it, but you won't have to use a web browser. [NOTE: for some reason the slider for pressure starts out at 0.5 atm].

How to Use this Interactive Plot

By moving the three sliders you can adjust the values of:

If you click on one of the [+] buttons at the right of each slider, you can see the actual numerical value for that variable. You can then use the "-" and "+" buttons to decrease or increase the value in discrete steps. You should be able to type in a number into the text box (and hit the [return] key) though this may not work well on some web-browsers. The "play" button will animate the plot as a movie. Note: there are a few calculations going on behind the scenes, so it may take a second before the plot updates in response to moving a slider.

The colored curves on the plot represent the following:


  1. H.E. Bass, L.C. Sutherland, A.J. Zuckerwar, D.T. Blackstock, and D.M. Hester, "Atmospheric absorption of sound: Further developments," J. Acoust. Soc. Am., 97(1), 680-683 (1995).
  2. ANSI Standard S1-26:1995, "Calculation of the Absorption of Sound by the Atmosphere" (ISO 9613-1:1996).