Would this hurt people with cochlear implants?

The interesting parts are those 25KHz transducers which seem identical to the 40KHz used since likely forever in ultrasound remotes and more recently in collision avoidance sensors for robotics. I did a small search and found mostly high powered ones at that frequency, probably ultrasound cleaners spares, or smaller but a lot more expensive transducers compared to 40 KHz ones. Does anyone know of a source for these transducers?

I also wonder if a simpler approach could be used since the purpose appears to be (can't understand the math) generating noise by driving randomly a number of oscillators around the transducers resonance frequency then induce subharmonic vibrations into the MEMS mics through etherodyne operations between these sounds. If that's how it works, then the DDS chips, the Arduino and the code might be swapped with a less random but likely equally functional set of dissonating oscillators modulated by LFOs (all doable with plain old logic gates); not unlike the old school way of generating cymbals metallic sound in analog drum machines. Here's the Boss DR110 relevant schematic as an example.

http://www.sdiy.org/richardc64/new_drums/dr110/dr110a1.html

the original paper on jamming microphones and/or using them for covert data transmission: https://synrg.csl.illinois.edu/papers/backdoor_mobisys17.pdf

it seems to me that this is largely an attack on common preamplifier circuitry. would it be sufficient to ensure that the preamps implement low pass filtering? or is the issue more in the microphone element?

This is really neat work. I'm curious to see if smaller and more portable versions of this can be made - obviously a prototype is always going to be bigger and be relatively limited. Now that the research has been surfaced, this appears easy enough to follow so it'd be neat to see how electronics enthusiasts run with it.

I think this is a neat idea, but I suspect it would be more useful as a standalone device than as a wearable. Devices like this could be installed in secure rooms or deployed on the fly in discreet locations with a high rate of success, I'd guess. Arrays of them could work together for better coverage.

Still, this may be the only real option in public spaces (i.e. outdoors). If you're okay with people knowing that you're trying to avoid being recorded, then this would probably be fine.

Sure it's "wearable" if your definition of "wearable" is incredibly loose.

I can see this being useful for blocking your smartphones and Alexas, but it seems like devices specifically designed for surveillance could start being designed to fix this exploit.

How will this impact calls? If somebody is wearing this in a public space then any callers in surrounding area will have problems, no?

It would be interesting to evaluate this device’s impact on telephonic conversation!

I hope there is a switch to turn the device on/off. Otherwise you won’t be able to talk on the phone :-)

What could go wrong with blasting out ultrasonic noise in every direction? (Besides a lot of confused dogs...)

Another discussion of this: https://news.ycombinator.com/item?id=22339548

A similar effect occurs when using infra-red LEDs near the face to prevent video recording. The problem is that many phone cameras now have a UV/IR filter - I can see microphones having a similar setup to improve sound quality in the future.

This might result in jammed audio for human listeners, but recovering the original audio seems like a fairly mundane signals extraction problem subject to the standard signal/noise ratio issue.

Is sound of that frequency naturally directional? Wonder if an omnidirectional driver / sound source could be used to prevent the "dead spots"

Can someone please explain what is stopping these recording devices (Alexa/phone/etc) to filter out ultrasound?

> The leakage is caused by an inherent, nonlinear property of microphone’s hardware.

Interesting, what are related theories I can learn about it deeply?

Won't somebody please think about the dogs

The world is in a sad state of affairs when smart people feel the need to create wearable jamming devices.

And this is also likely very illegal...

It seems a little irresponsible for an academic publication to make a claim like

> always listening, recording, and possibly saving sensitive personal information

without any evidence to support it. I get that they're just setting up context for their device, but they're also making some pretty serious (and widely disproven) accusations.

I would think this would function better as a hat than a bracelet.

Stylish!

fuck dogs amirite