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The waves of a typical kitchen microwave oven have a wavelength of 12cm while the audible spectrum is between 1.7cm and 17m, so one might think that they overlap and that kitchen microwaves should be audible.

Are they, are they drowned out, or blocked by the appliance's cage?

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There's more to waves than just the wavelengths. Microwaves are a form of electromagnetic waves, which means they're oscillations of electric and magnetic fields. Sound waves, on the other hand, are compressions and decompressions of air. Our ears are sensitive to the latter, but not to the former. (With our eyes we can detect electromagnetic waves, but only over a limited range, and microwaves fall outside of this.)

While this is true in general, there actually exists a somewhat ill-understood microwave auditory effect where people perceived sounds due to electromagnetic radiation at microwave/radio frequencies. The cause is thought to lie in the radiation heating parts of the inner ear, leading to a perception of sound. You will not observe this with your kitchen microwave, though, since that was designed to not have any radiation escape.

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The frequency of a kitchen microwave is 2.45 GHz. Our ears hear frequencies between 20 Hz to 20,000 Hz. If electromagnetic radiation was turned into sound waves somehow (although they don't couple to them at all strongly), the frequency would be preserved, and not the wavelength. Thus, you cannot hear microwaves.

You can sometimes hear a 60 Hz hum from AC electricity, which can get turned into sound waves by transformers, and sometimes by other mechanisms.

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  • $\begingroup$ How do 2.45GHz translate into 12cm and 20-20000Hz into 17m-17mm? Why do the wavelengths overlap but not the frequencies? $\endgroup$ – SeanJ Jun 4 at 14:25
  • $\begingroup$ Based on your answers - thanks guys - I can probably answer that myself. Frequency can translate into different wavelengths depending on the speed of propagation with sound waves traveling slower than electromagnetic microwaves. So the same Hz count can translate into different wavelengths. Is that correct? $\endgroup$ – SeanJ Jun 4 at 14:30
  • $\begingroup$ @SeanJ: That's correct ... the reasons that these don't match up is that light travels a lot faster than sound. $\endgroup$ – Peter Shor Jun 4 at 15:12
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Microwaves are electromagnetic-waves and sound waves are pressure-waves. Our ears react to pressure changes and not electromagnetic radiation, which is what our eyes does instead. So no, unless there is some reaction in the atmosphere or air which might induce sounds (i can't remember the name of this process) you will not be able to hear microwaves.

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