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Are absorption and attenuation different words for the same thing? Wikipedia separate has articles on Absorption (Acoustics) and Accoustic Attenuation. I don't see a clear physical distinction between these two concepts, but I also don't know much about acoustics. Both seems to measure how much energy is dissipated from a wave passing through a material. Are they genuinely different, or is this a case of different areas having their own terminology?

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Attenuation is the reduction of power in a signal/wave/whatever-suits-your-field, and absorption is one process of attenuation. However, there are other sources of attenuation as well, such as scattering/reflection of acoustic waves off of surfaces for example.

Attenuation and absorption are both terms used in a variety of different fields. In my own for example, photonics we experience attenuation through absorption, scattering and reflections as well. These three are different processes with results in attenuation of a signal. You can view maybe attenuation as the opposite of gain/amplification.

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    $\begingroup$ Yes, this answer fits my understanding as well. Absorption is one process within the broader set of processes that cause attenuation. $\endgroup$ – D. Betchkal Nov 3 at 17:30
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In the acoustic nomenclature, attenuation and absorption describe two different things, both related to loss of the sound wave energy.

Attenuation is the continuous dissipation of energy in an acoustic wave as it is propagating through a medium. If you have a sound wave in air travelling from A to B, it will be weaker when it arrives at B. The reason is that energy has continually been dissipated on the way by the medium's viscosity, thermal conduction, and (in air) molecular relaxation.

Absorption is when the sound wave suddenly loses a lot of energy after encountering an object. For example, when a sound wave hits the wall of a room, it will be reflected back, but the reflected wave will be weaker because the wall absorbs part of the energy. Different materials absorb energy to different amounts. Concrete absorbs very little, wood absorbs more, and the walls in an anechoic chamber absorb almost all of the energy in the impinging sound wave, so that the reflected sound is extremely weak.

Thus, in short, attenuation is a continuous energy loss as the sound wave is propagating, while absorption is a sudden energy loss when the sound wave encounters an absorbing object.

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  • $\begingroup$ I'd rather say that at the interface of air/wall part of the signal is transmitted rather than absorbed as this is not always the case. Walls can propagate a pressure signal as well. $\endgroup$ – DakkVader Oct 25 at 6:01
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    $\begingroup$ Fair point; the description I gave is simplified, and you're right that the sound wave energy is transmitted into the wall. Depending on the wall, it might be quickly converted into heat (as with very porous materials like anechoic chamber walls or fresh snow) or even reflected on the other side of the wall and partly transmitted back into the room. But from the perspective of the sound field in the room, sound energy disappears at the walls by absorption. $\endgroup$ – Erlend Magnus Viggen Oct 25 at 7:42

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