alt Hacker NewsThis has some very interesting privacy and security risks. If the tech can do more complex frequency analysis, then couldn't it essentially be used as a microphone for a device that doesn't need permission.
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It's a pretty well-known exploit that the CIA is capable of turning a lot of electronics with speakers into microphones. I imagine there is an entire classified backlog of things they can turn into microphones without the target's knowledge.
I don't think that's realistic. If you're looking at the acceleration sound waves cause against a phone's accelerometer, that's likely far below the sensitivity of the sensor- phones are too massive relative to the force of sound waves from speaking. F=ma, so the acceleration you're looking at is the force of the soundwave (tiny) divided by the phone's mass (relatively large). The only reason this kind of works is because you're putting the phone on an object that's mechanically vibrating. I suppose it would work in certain situations like putting the phone on top of a large speaker, but you'd never get the resolution to decipher audio from sound waves alone for a phone sitting on a desk or in a pocket
I doubt the sampling rate is anywhere near what you would need to make out dialog in a sound recording. You might be able to tell who is speaking though if you had a voice profile.
Sounds like you've got a great idea for a proof of concept for DefCon next year...
I thought this has been done to capture keystrokes of a keyboard next to the phone already
2011 https://www.researchgate.net/publication/221609349_spiPhone_...