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Why when I have music on in earphones and I have them resting on a desk, the music sounds different, like in a different tonality/pitch to when I am actually using them?

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Ron is not far off the mark but I have always thouught it was the difference between inductive and radiative coupling. A free-standing speaker must couple all energy into the air, where the field attenutates as 1/r. In the near field zone, however, inside this wavelength, there is also the inductive field, which attenutates as 1/r-squared. If you are far from the speaker this component becomes negligible, but in the near zone, it is still effective. That's why you can transmit from the earphone to the eardrum. It still goes through the air, it's just takes advantage of the near-field effect.

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  • $\begingroup$ I don't know if this is entirely true--- it might be true for foam padded speakers. I always thought that it was contact effects, but the range of the transmission is certainly less than a wavelength, so near field effects will be important. $\endgroup$
    – Ron Maimon
    May 1, 2012 at 3:53
  • $\begingroup$ +1: this is the correct explanation. I deleted my answer. $\endgroup$
    – Ron Maimon
    May 1, 2012 at 12:49

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