Think of all the different types of microphones that are in common, and uncommon, use for capturing sound traveling through air...
Do you notice one thing that is in common with all of these types of microphone? Yes, they all have a diaphragm. In every case, sound must contact and move a diaphragm before it can be turned into a signal.
The Heisenberg Uncertainty Principal
Yes, I thought that would make you sit up and take notice. A generalized form of this idea states that the process of taking a measurement disturbs the object or phenomenon being measured.
So the act of placing a diaphragm in a sound field changes the characteristics of that sound field.
This means that however accurate a microphone is, it is always limited by the fact that the presence of the diaphragm disturbs the sound field. A lighter diaphragm would obviously be better but, even so, it is impeding the motion of air molecules. Its acoustic impedance is different and therefore a barrier to the transmission of sound from air to diaphragm... there are probably a whole host of reasons why a diaphragm is in general a 'bad thing'.
Clearly the limitation here is that vibrational energy traveling in air is being transferred to vibrational energy in another medium. Surely it would be better to be able to measure the motion of air molecules without asking them to give up their energy?
Suppose for example that it were possible to color air molecules so that they were visible. Now, their motion could be tracked by light sensors - no intervention necessary. Or if air molecules could be made radioactive, perhaps a radioactivity sensor could track their motion.
Rather than leaving this as a flight of fancy, it really does seem that we have exploited the possibilities of the diaphragm to the absolute limit. To progress microphone technology further, a different approach will be necessary that is not invasive to the air molecules that are carrying the sound wave.
So how could it be done?
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