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Wearable Microphone Jamming (uchicago.edu)
360 points by graderjs 7 months ago | hide | past | favorite | 123 comments

Interesting to note that someone opened an issue in the linked GitHub repo mentioning that the system doesn't work with iPhone 8 and above:


edit: Looks like (from the reply) it's the waterproofing membrane over mic that's rendering the jammer useless.

So, if you're recording a cop in the next few years, make sure to use a waterproof phone.

You may find a small bit of capstan tape over the mic will, whilst reduce the mic's sensitivity a little - equally achieve the same results against this.

*Kapton tape, presumably. A capstan is an interesting thing though: https://en.m.wikipedia.org/wiki/Capstan_(nautical)

Slightly more recent reference to capstan use is in the context of cassette players/recorders. Same idea, a driven ridged head pulling the tape [1].

[1]: https://en.m.wikipedia.org/wiki/Tape_transport#Capstan

yes, thank you for clarifying and dispelling the confusion my spelling opps did there.

Police wont't generally use something like this as it would interfere with bodycam which includes a microphone.

"Police officers in Beverly Hills have been playing music while being filmed, seemingly in an effort to trigger Instagram’s copyright filters."


What I find ironic, is the police are doing a copyright infringement (unauthorized public performance of these songs) in order to infringe on citizens' rights. Why are record companies not more pissed about this?

Because they don't lose money over it the way they do over other types of unauthorized public performances.

I think I'd phrase that a bit differently.

Extracting cash by threatening mom and pop restaurants for playing the radio is old hat, nobody cares.

Threatening cops over it is going to attract attention.

Because it doesn’t have any impact on sales, and the executives of those companies don’t want to pick a fight with the local police (who could practically, if not legally, retaliate though various means)

It's not performance as there's the lack of intent to have others hear it and few will. You can play music for yourself in public even if others overhear.

Doesn't playing a song with the explicit intention of having it be recorded count as having intent to perform?

It's really curious in this case though, the intent is for the music to trigger automated software that prevents performance. Hard to classify that as 'intent to perform' especially with USA's Fair Use.

My understanding is in UK causing a recording to be made (whether viewed or not) would be infringing. We have Fair Dealing but it's extremely restrictive compared to Fair Use.

Just my personal, private opinion.

Does it suggest that system of IP is genuinely designed and deployed to protect art? Or capricious exercise of state power?

I will double down with, no, the system of IP is not intended to protect art. The whole concept of IP is antithetical to the intent of copyright.

“Article I, Section 8, Clause 8, of the United States Constitution grants Congress the enumerated power "To promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries."”


The cops are not trying to post their footage to the socials. They want you to not be able to do it. If they need their footage, it's to prove you were being an asshat and deserved whatever happened to you. If you need their footage, it'll mysteriously not be available for some technical or clerical error.

Why depend on their footage? We need to record them ourselves. Counter their surveillance with our own sousveillance.

It's almost like you missed the point. The cops are playing music because someone else is recording them. That is the counter surveillance.

Copyrighted music won't prevent video of cops breaking the law from being used in court, so don't let that tactic dissuade you from recording the police.

Right, but it does help them keep videos from being spread as easily if they get taken down. It sure does seem like the only reason cops ever get punished is public pressure, which relies on people seeing the video.

Its to provide a PoV from the police officer, yes. Because the PoV of the other side (whatever it might be) may omit details, or could've been tampered with. You're right that it is in the interest of the police (in general, not necessarily the police officer), but if details like sound are not available that only hurts their case.

> if details like sound are not available that only hurts their case.

Unless the cop is saying things they shouldn't be saying. I think you are missing the point of the comment you are replying to. They are saying that cops only use that footage when it benefits them (that's assuming the footage exists and they didn't "forget to turn on their camera") and when it doesn't benefit them then they won't release it or the footage might get "lost". Also the police have been known to edit or post misleading footage to their own gain.

'Their own gain', the police work for the public interest. If that isn't the case, something is wrong with your police force.

I get such point is popular with people who are cynical to authorities, and I get that in the context of racism in USA.

Here in The Netherlands they are always recording, and when the cop pushes it on, it saves the last minute before the cop pushed the button as well, for context.

The police are not allowed to tamper with evidence in a court of law. Nowhere in the world is this allowed.

> 'Their own gain', the police work for the public interest. If that isn't the case, something is wrong with your police force.

I agree. Something is very wrong with our police force. Also, it might not be allowed anywhere in the world but it absolutely happens in most of not all places (police getting away with tampering with evidence).

If we cannot keep people who are supposed to protect us accountable (even via a trusted third party like internal affairs [1]) we as society have a problem. And we do have a problem: a problem of trust, at the very least.

I'd like to think they do get caught, and I'd also like to think most cops in society can be trusted. There's dirty (and I use that word liberally) cops everywhere in the world, yes, also in The Netherlands, but the rotten apples are in a minority.

Mind you, my original quote was: "Police wont't generally use something like this as it would interfere with bodycam which includes a microphone." I said generally; I was already aware -in a world-wide context- some dirty cops might do such, or that I could think of exceptional situations where such might be warranted.

[1] https://en.wikipedia.org/wiki/Internal_affairs_(law_enforcem...

the fundamental problem is that the majority of good cops dont rat out the minority of bad cops, either out of a sense of brotherhood or because theyll will face retaliation if they do. The "rotten apples" saying, of course, is that a few rotten apples spoiles the whole bunch. Good cops don't just suddenly snap one day and commit corrupt acts out of nowhere, the people they work with know what they are like and what they do.

In many countries this is unauthorised broadcasting.

Why can’t instagram distinguish between a public performance vs a cop playing music. Should be pretty easy to do.

Doubt it. Copyright violation detected is fully automated for the most part, and very good at detection regardless of background noise.

You would need a human viewing footage and listening for every single post to determine this.

The challenge is determining between music playing in the background of a real-life arrest, vs the same for a fictional arrest where they would want to claim copyright usage fees.

That's a hard job for most people, nevermind an automated system where the copyright holder doesn't care about false positives.

That is exactly why they would use something like this.

> it would interfere with bodycam which includes a microphone.

That's the point. Many cops do not like the fact that the bodycam also records them to a degree. At least the ones getting caught planting drugs in stopped cars or mistreating people because they forgot about the cam.

That is unless they use waterproof body cam.

That would likely be seen as a feature

How sweet!

Maybe just don't commit street crimes.

That may well be fixable, case of what is the resonant frequency of the water protection an tuning this to induce resonance to overload the sensor - may well work. Though inducing resonance in the glass screen may well achieve the results.

I'd also be interested in testing this with contact mics as from my experiences - this may not work upon those at all.

Cool research. Given that you are also jamming hearing aids and other microphones, don't think it's practical to be used in real life.

Off topic: check out Pedro's other work http://plopes.org/

Definitely thought provoking research :)

Depends of what real life scenario is.

A cafe, maybe not. A meeting room, likely yes. There at least you can declare that a hearing aid is used. The very point of the device is to jam other microphones.

Not going to last very long, though; ultrasound filters will soon appear on all relevant gear, including mobile phones.

The microphone's worst enemy is the pencil.

((Just wait until some scrappy thesis describes how to determine character being written by pencil based on the vibrations of sound being made from the friction between a carbon based utensil and a paper pulp based medium such that the intended letters can be derived based on the length, count and direction of the audio signals derived from the sounds of the writing utensil against the medium.

You know, that sounds like language from a patent application.

I actually AM licensed as a patent agent, but I'm not practicing so I can't get you that patent.

Also that's now prior disclosure and could be cited against the patent application.

Careful, Mordechai Guri can hear you!

If that meeting room also has remote attendee's then that may well prove the issue.

However with ultrasonic filters - you could cone of using this.

Then such approaches have often been used like vibrating windows to curtail laser microphones and yes the trick of taping a vibrator to the window does work - though not in keeping with your boardroom aesthetics unless your Anne Summers or the like.

> Not going to last very long, though; ultrasound filters will soon appear on all relevant gear, including mobile phones.

Only if this technique actually gains widespread use. Even then, it will most likely only appear on gear that must still record, such as body cams. For consumer tech, this would just be additional costs, which the manufacturers are not going to bother with.

I think the parent refers to if a hearing impaired person with hearing aid is present in the meeting room ...

yeah, then the ad tech is just moving onto the next best thing. SDR.

If I have a relationship that gets me into a conference room with some people, I'm not going to run a fucking microphone jammer there.

If I had someone in my conference room do that I would be extremely sketched out.

It's not about the people they see in the room, it's about the people they don't see in the room.

Cool studies. He sure came a way from his earlier "human component motion platform" (AKA "have your buddies lift and shake you while in VR")

To test the hearing aid, just walk into your local cafeteria at around 2pm (aka dinner rush), and see how many people start reaching for their ears.

This is the research inspiring Naomi "Sexy Cyborg" Wu's wearable microphone jammer (a choker), see https://youtu.be/H1rozZ7ebxQ?t=111 and later on at https://youtu.be/H1rozZ7ebxQ?t=1319 for live testing out in public.

I wonder how portable these could be made to use when visiting someone who owns an Amazon Alexa device?

It's harmful to constantly hear sound, I wonder if it's our perception that makes it harmful even if we don't realize that we hear something? Is it harmful to hear sound threats outside of our range? Is it harmful to constantly use active noise cancelling?

> It's harmful to constantly hear sound, [...]

Hmm I'm not so sure about that; do you have any source for that? My intuition says that it's nigh impossible to find completely quiet places in daily life; there's always some noise, though it could be imperceptably quiet.

If constant sound is harmful, I'd imagine we'd all have lost our hearing by now. I reckon any harm woulc come from volume, not just simple presence.

> If constant sound is harmful, I'd imagine we'd all have lost our hearing by now. I reckon any harm woulc come from volume, not just simple presence.

That's assuming it's physically harmful (to the ears). If it were instead mentally harmful, what you would expect is for the incidence of mental illness to increase as life got noisier and noisier (with a lag, of course, assuming this effect takes an appreciable amount of time).

> It's harmful to constantly hear sound

Are we saying our brain is not processing sound while we sleep? Ain't we hearing sound 24/7?

I am curious about ANC as well. I used to wear headphones with ANC 8h+ a day and started to hear noise in my ear.

I don't see why that would happen. ANC plays an inverted signal to counter noises. It's not just perception that it makes sound quieter. When the original sound wave and counter sound wave collide they physically cancel out.

If im understanding GP correctly, I think what's happening for them is that the extended quiet daily makes their hearing a bit more sensitive (as their brain and ears work in tandem to amplify the sound and be more receptive to it, respectively). Now when they take off the headphones, since their hearing is more sensitive, they pick up more of the actual background noise that exists around them.

Right, that's the ideal case. What might happen is that you get incomplete cancellation that varies with frequency; so you might get higher sound pressure at certain frequencies.

Fascinating and I like how cheap it can be made - those ultrasonic emitters are right of a HC-SR04 by looks of it and those are cheap as (got half dozen for £1 each few months back).

I did start a project to jam gopro's (audio and visual recording) - was combination of IRDA emitters and resonance inducing the housing - but this is less niche and focused. My design was to use a hat with sensor emitters attached. Though canned progress after friend asked if it could disable a police body-cam, of which I said no and yet it probably would and morally weighed up the pro's and con's and canned that.

This is surprisingly simple tech!

Those signal emitters look very similar to ultrasonic distance measuring modules you can get at component/DIY shops.

I wonder how sensitive dogs would be to such a jamming system.

At a guess, they wouldn't notice the sound after identifying it as not requiring their attention. They have very pronounced adaptive habituation to our noises.

Can confirm. Building a large metal qwanzit-hut and pounding and drilling etc, and the dogs were unphased.

Dogs can perhaps hear up to 45,000hz. This emits tones within that range.

Article says at 1 meter the sound is mostly less than 70dB and less than 80dB in hot spots.

So probably not too bad unless I'm missing something.

70-80dB is really very audible. I'd imagine much worse for dogs given how sensitive their hearing is.

edit: Must confess I'd not thought of the potential effect of the device on animals.

> 70-80dB is really very audible.

Not at ultrasonic frequencies it isn't (eg at 45KHz)

Plus unless it's dbm (or similar) the statement is meaningless.

So this system would serve two purposes and not just one.

It's more that the jammer could easily be detected by a change of pet behaviour.

As a long-time hearing aid wearer, I too notice the absence of background noise whenever I flipped on my ultrasonic transducers … back in 1976.

How about camera jamming with UV (for example, on your car's license plate)?

I imagine this has been discussed on HN before (if so, just send me the link),

that could be defeated with a simple UV filter over the camera lens, likely already in place

ir camera jamming is doable and well-known enough to appear in media like crime dramas

none of it is very practical because you're still extremely identifiable as "that one with all the lights" and presumably still visible in the visible spectrum

when police jam cameras at protests they just use bright visible strobes

Glass and plastic typically used in camera lenses already blocks UV. Enough UV to upset a camera would be enough to give you cataracts.

Infrared is a different story but most cameras have IR filters. Security cameras sometimes have one that only drops in during the day to enable daytime color and nighttime IR.

> when police jam cameras at protests they just use bright visible strobes

Ironically then the story just goes from "here police are brutalizing the people protesting brutality" to "and also being childish with their flashlights." Bright lights aren't nearly as blinding to large-sensor cameras with good lenses as they are to cheap cell phone cameras.

Or buy the super dark glass like plate cover just like the ghetto Los Angeles people use.

Why not active countermeasures? Camera detection device coupled with lasers.

Are they not able to just use phase shifts and beamforming on the transducer array instead of the odd keep-moving-your-bracelet design?

The case would be if someone is recording you with a microphone placed somewhere unknown in the room. With the bracelet, and humans' tendency to move their arms while speaking, microphones around the room will be jammed at least part of the time.

But you could surely just randomly vary the beamforming to get the same effect, right?

Beam still has to be in the direction of the mic, which wouldn't help if your body is blocking most of the direct waves. You get some scattering, sure, but I think ultrasonic is pretty absorbable, right?

But the same is also true for rotating the bracelet isn't it?

The bracelet does not have directional speakers, so the ultrasonic waves will kind of spread everywhere, bouncing off hard surfaces, and ultimately reaches the eavesdropping device.

Say goodbye to your cat...nevertheless, it could be a useful device under certain circumstances.

Previous HN discussion for this (2020 Feb) (236 points): https://news.ycombinator.com/item?id=22367733

Interesting trial. But I'm sure there will be techniques to clean the noise out.

I'm wondering too. I had a glimpse at a paper and it seems it works because even though ultrasound is "inaudible to humans, still leaks into the recorded speech due to non-linear amplification of the microphone’s circuit". The chart thought shows the leakage has small dB (-20) in audible spectrum.

Too bad researches didn't leave any samples of recording in the repo. Curious how it would be effective after: 1) filtering frequencies to 0-16kHz 2) getting 1-2sec sample duration of noise profile while nobody speaks and using noise reduction filter from audacity

The idea is that the analogue components are saturated already so there's no available margin for the lower frequencies to further actuate the diaphragm or amplifier.

lots of circuits will fold higher frequencies down into lower frequencies (but at lower energy).

If you can generate enough energy, you can push enough energy into other circuits that they saturate (reach the end of their working range) and will output noise.

Non-linear circuits l̶o̶t̶s̶ ̶o̶f̶ ̶c̶i̶r̶c̶u̶i̶t̶s will fold higher frequencies down into lower frequencies

Pretty much most circuits are non-linear, for real-world circuits "linear" just means "linear within normal operating range"

Download the audio from the YouTube video at the top of the page - it has a sample in it

I can see the next paper being extracting jammed audio signals using deep learning.

It's a great idea and I would be interested in something like this for myself. Except they would need to figure out how to reduce the size of that device. It's technically wearable but still quite huge.

It's illegal for movie theaters to jam cell phones. If this actually works and becomes popular, I don't imagine it would take too long before this became illegal too.

It is illegal to jam a cell phone's EM signals, and it isn't because of the jamming's effects on the specific phones, but because of the jammer's unauthorized transmissions in regulated radio frequencies. The FCC takes their job fairly seriously, especially when someone makes a product that is designed to break their regulations. But, the FCC has no jurisdiction over sound.

>the FCC has no jurisdiction over sound.

Until they need to.

It is Illegal to jam the phone signal in case of emergencies AFAIK. Not aware of it being illegal to jam recording devices in such an environment in which they do outline (somewhere) no recording allowed in the theatre.

Audio is an odd thing in law - in the UK I can record many things audio more than you would legaly be allowed to video.

But privacy laws are the ones that curtail video recordings mostly and with that - this kinda sits on the other side of the fence.

However - public nuisance may prove an area and pets may well dislike this, so if anything it may be classed as an assault upon an animal. Depending upon the impact upon animals like dogs.

So my main concern would be public area's with people using guide dogs - will this cause the dog distress and what would be the impact.

So I'd imagine already laws that may see this fall foul of - but like many things it will be how it is used and not ownership.

jamming recording devices will make phones useless for emergencies, no one can hear you

Sound levels in movie complex's - you would struggle anyhow and why people leave to the foyer or toilets to make calls when movie playing.

Wouldn't it be easy to build a microphone that was immune to this? Up to now, there was little need to do so.

I wonder if a de-jammer ML model could be built to restore the original audio?

Now we know a possible cause of the Havana Syndrome...microphone jamming.

How quickly are they going to go commercial with this?

I've seen such devices openly sold years ago, and heard of them probably a decade ago (meaning you could buy them well before that if you had the right contacts, but unless either spying or preventing it is your job, you wouldn't have those).

No one is going to buy this. It doesn't jam your voice at all. It introduces enough distortion and noise so that computer speech recognition software gets 4/5 words wrong.

Let me make a comparison. Claim: Those capchas with "type in the word you see" have an error rate of 4/5 letters when read by a computer. Yet here we are, humans, reading them just fine.

Now, if you're a conspiracy theory fake elected moon landing virus hoax person who is afraid of the government having microphones everywhere, running a keyword search on microphones placed around the park.... Still not a jammer - I'm sure whatever voice recognition software this thing confuses, the government has much better ones. Simply from the fact that most of the people they're interested in have accents so thick it's worse than some added "jammer" noise.

But to answer your question, "sounds" like they're trying to go commercial soon, because their announcement of this dirt simple product sounds like a cheap advertisement for some dick enlarging pills. meanwhile, your phone speaker can make sonic sounds since they support a sample rate of over 44khz. So can your computer.

here you go. you can google and download some files to play too. https://mynoise.net/NoiseMachines/audioJammerNoiseGenerator....

I’m not worried about the government spying on my individually, the resources to fight that would be impossible

I am worried about large companies spying on me en mass (and selling or leaking that information). That requires automation (voice/face recognition), it’s also reality, not a conspiracy theory, alas I do see it as inevitable and there only so much you can do to fight it.

> Yet here we are, humans, reading them just fine.

I've met a lot of captchas that I couldn't reliably solve. I guess that proves I'm a robot.

Same here. My guess is that they constantly AB test/explore captchas to push the envelope of genuine humans users in order to make it as hard as possible for the bots.

This is great for meetings. Don't have to ask everyone to put their smartphone off. Just be in a private room without cameras (against lipsync and other private details leaking such as notes).

Re: Your computer/phone can make noise. They use an Arduino to power this thing, and it manages to block with natural body movement.

I'm pretty sure this is going to ruin ANC headsets too though.

So what is the effect in the first part of the video on the website then? Are you saying they‘ve faked it?

It just relies on cheap microphones being fairly non-linear.

A quality microphone, with a decent low-pass-filter would be immune to this kind of hack.

Think about it, why aren't our ears affected?

> why aren't our ears affected

they're affected listening to the raw microphone capture. that's because the noise generated is much louder than the speech. so listening to raw microphone capture with this thing on, you can't make out words at all - just a few syllables here and there. the key is that the full voice signal is still captured by the microphone. you then filter out the additional noise (your conference software and laptop microphone does that at a shitty level, rtx voice is the top consumer product for this). once the noise is gone, you have only the original voice. due to the filtering, the original voice is very lightly garbled, which is enough to confuse voice recognition software, not your ears.

notice how they're using voice recognition to measure success? that's misleading and on purpose. if they used a person to see if this product is effective, the result would be - the product is literally nothing but a loud noisemaker which in zero ways does what it says it does.

now, I don't have an rtx. if you want to screw around, here's a very shitty two megabyte software version of what rtx voice does, it's open source and just a couple of meg. https://antlionaudio.com/blogs/news/free-active-noise-suppre...

a low pass filter, or a nice microphone would not help you at all here - the white noise is in the vocal range and no simple frequency filter is going to remove it. their product makes ultrasonic noise, which (probably due to microphone resonance) makes the mic vibrate in the audible range. again, not affecting the original voice signal, so it's loud white noise overlaid on top of the voice.

it does seem putting something in front of the mic that absorbs ultrasonic frequency but not lower voice frequencies works well to block this. which is why the thin plastic waterproofing film over the phone microphone completely blocks this product - no noise removal filter needed.

So literally any smartphone with water resistance bypasses this thing and records fine. for the rest, just run a noise removal filter on the recording and listen to it. for governments, I'm sure their spy mics are waterproof and immune, and if not, their voice recognition is better than whatever consumer tech these guys tested it on.

> they're affected listening to the raw microphone capture.

Well, of course.

But I was talking about listening directly, not via a microphone.

The whole point of the device that the white noise is not evident to listeners in the vicinity. If it was, people would not be able to speak to each other.

Which means that it's caused by intermodulation in the crappy microphone. Therefore a better quality mike (and a LPF) would remove it.

No, I'm saying that does literally nothing but add noise. It does not block or change the original signal in any significant way for human ears - only for consumer-level voice recognition software. Which is extremely crappy even without noise for anything more complex than "hey google play some ads in the middle of this song."

Once you take the noise out, the voice recognition software has problems recognizing the words. People do not. You can take the noise out at home with lots of different software or hardware. Skype/teams/zoom do this on a very basic level by default - as do most microphone audio drivers in windows. Once it's taken out, distortion from the noise is just enough to make the voice recognition miss a bunch of words. Human ears do just fine though.


There is a short sample of audio in the YouTube link. Your video is not even remotely similar in sound. If you could take the audio from the original and extract easy (for humans) to understand speaking, your confidence that this won’t work would be obviously justified. But so far you don’t appear to have even understood how the device works.

>It prevents [...] our camera from eavesdropping on the conversation

How does it prevent the camera from filming speakers' lip movements?

> * denotes equal contribution

Wow, this otherwise typical four-student team was that equity-stuffed to maintain some level of equal outcome.

But... they completely forgot what emitting loud noise is illegal.

That is awesome e

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