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Loudness of sound in air, liquid and solid

  1. Dec 27, 2009 #1

    It is common knowledge that the speed of sound is greatest in solids, then liquids and finally gases. But just thinking, if all things remain equal, how will the loudness of sound compare in the 3 states?

    My GUESS is that sound in gases could be the loudest. Loudness is defined as the amplitude of sound waves induced in the eardrums. In gases, the inter particle bonds is very weak, thus the gas particles can progress and strike the eardrums with maximal force, causing large amplitude. However, in solids, inter particle bonds is strong, thus these strong bonds will hold back the solid particles and the solid particles will not strike the ear drums with maximal force.

    Why do fellow forummers think of my reasoning? Will be very glad to hear from you guys and gals!
  2. jcsd
  3. Dec 27, 2009 #2


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    No, that depends upon the elasticity of the gas, liquid or solid- how strongly the material recovers from the distortion of the sound wave and so how little energy is lost to the material itself.
  4. Dec 27, 2009 #3
    Loudness is a subjective term. Measurement of "loudness' in air is the sound pressure level or SPL. See
    It is also defined in water, but with a different reference pressure:
    "Commonly used reference sound pressures, defined in the standard ANSI S1.1-1994, are 20 µPa in air and 1 µPa in water. "
    Bob S
  5. Dec 28, 2009 #4
    Hi HallsofIvy,

    Thanks for your reply.

    I understand the idea of elasticity (well, more or less). But i am not sure how the strength of elasticity relates to energy loss. According to your reasoning, does it then gather that the less strong the material recovers from the distortion of the sound wave, more energy is lost to the material itself? If so, what is the energy lost as? I mean, other than recovering from the distortion of the sound wave, what other outcomes are possible. (e.g. atoms moving about more randomly in other directions, other than in the direction back to the original?)

    My last query is : when we talk about a elastic material, does the word "elastic" mean the same way as "elastic" when 2 particles collide, resulting in no energy loss (i.e. in the context of elastic collisions)?

    Thanks everyone for your wonderful replies.
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