any speaker can be tapped into as a microphone by a motivated government.

Workaccount2 6 hours ago | parent | next [-]

No, because the drive circuit for a speaker is the opposite of the circuit for a microphone. The output stage of a speaker amplifier is just that, an output. The only way to record audio from a speaker, which is totally possible, is to have also purposely built an input stage also attached to the speaker. Which at that point you might as well just use a microphone...

Audio input and output are not reversible.

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Y_Y 5 hours ago | parent | next [-]

I don't know what you mean here, I can plug a speaker into my mic slot and use that to record, just as plugging a mic into the speaker slot gives a (crappy) speaker.

	▲	cdaringe 5 hours ago \| parent \| next [-]
		> purposely built input stage You moved your device to the purposely built input stage. Not an expert, but your remark doesn’t compute with the parent comment
	▲	15155 2 hours ago \| parent \| prev \| next [-]
		A DAC and amplifier circuit is electrically incapable of processing input (on its own.) Physically unplugging and moving a speaker to a mic input works, sure, but very few devices can do this switching electronically.
	▲	Workaccount2 4 hours ago \| parent \| prev [-]
		Because on your computer the engineers purposely put a switch that can direct the signal to either the input hardware or the output hardware. It's not a mic slot, it's a general analog I/O port with a 3.5mm form factor.

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stragies 5 hours ago | parent | prev [-]

on many cards they are, check out the tool `hdajackretask` from package `alsa-gui-tools`.

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Aachen 6 hours ago | parent | prev [-]

From a hardware point of view I've also noticed that speakers work like poor microphones (and LEDs like poor solar panels / light sensors), but is there any way to actually make this work on most devices without physically changing wiring? If the circuits aren't made to take measurements (or the software can't get at the readings) but only set a voltage on the wires, there wouldn't be a way to (ab)use this. I don't know enough about electronics to know whether this is commonly the case

Not that it's not a good thing to be aware of, but do you have any sort of source for what kinds of devices can have their speakers turned into microphones? Then I'll believe you about the government part

	▲	withinboredom 5 hours ago \| parent \| next [-]
		I don’t think they meant literally “any” but more like a device with a speaker could be delivered to you that has a speaker/microphone. Like a Bluetooth speaker you order of the internet. It seems it would probably have to be personally targeted to you, but in that case, there are probably simpler ways.
	▲	stragies 5 hours ago \| parent \| prev [-]
		Many a soundcard supports changing jack "direction". Here's a StackExchange answer from 2012, on how to do it with the GUI tool `hdajackretask` : https://askubuntu.com/a/911961