Mic Jammer Relies On Ultrasound

July 23, 2026 by Zoe Skyforest 15 Comments

Today’s phone microphones are perfectly adept at picking up sound in all sorts of conditions, and they’re backed by all kinds of processing techniques to filter out noise and capture clean audio. [mcore1976] has been working on a device to jam phone microphones that might be listening in, however, countering fancy processing techniques in turn.

The build uses a microcontroller brain to control an array of ultrasonic transducers. [mcore1976] has created many revisions of the project, each time improving its ability to jam microphones in modern hardware. The latest revision uses an RP2040 microcontroller and a MOSFET drive stage to control 20-80 ultrasonic transducers. They’re driven with a PWM signal generated from the RP2040 itself. The signal output is specifically modulated to try and confuse the automatic gain control systems used in many modern phones in order to make it difficult for them to record clear audio when the jammer is running. As [mcore1976] demonstrates with an iPhone 17, his voice is completely lost amidst unintelligible garbled noise while the jammer is switched on.

It’s a niche idea, and perhaps most interesting because it affects phone microphones while being largely inaudible to the human ear. We’ve featured other interesting jamming devices of late, too. Video after the break.

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Speak Silently With An Ultrasound Probe

July 12, 2026 by Donald Papp 14 Comments

Speaking is much faster than typing, and while it’s an increasingly convenient way to interact with computers, it’s hardly private. Providing speech privacy in a way we haven’t seen before is this prototype tongue-reading system that uses machine learning and ultrasound to read tongue movements and turn them into decoded speech. Not only can a user speak without emitting a sound, since it doesn’t read sound waves it’s completely immune to noisy environments.

Tongues are a far richer source of speech data than reading lip and mouth movements.

It turns out that tongue movements are a very rich source of information about speech, and an ultrasound probe under the chin takes very clear video of a tongue. With a dataset consisting of only around 50 hours of training data, the system has a 15.6% error rate and generalizes across different speakers (as long as they speak with similar accents).

That error rate may seem high at first glance, but keep in mind this is for a prototype system built in a month around a relatively small training dataset. All indications are that better results are just a matter of better training.

Probably the biggest drawback at the moment is the size of the ultrasound probe and the way it must be held under one’s chin like a contact microphone, but at the moment the probe is an off-the-shelf model that is hardly optimized for either size, weight, or wearability. If the system seems promising enough, a probe resembling an adhesive patch might even be possible.

It’s certainly a different approach from others we’ve seen in the past, including whispering while inhaling and reading lip and mouth movements.

Pico-Driven Ultrasound Enables Scaled Acoustic Model Of Home Stereo

June 8, 2026 by Tyler August 2 Comments

There are plenty of ways to get sound into your house: good old fashioned headphones, the Dolby surround setup we all lusted after back in the day, or the 21st century’s ubiquitous soundbar, with its ‘spatial audio’ magic. Which will work in your space? If you were an audio engineer, you’d set up listening area and use a microphone to map the space– but that would be thousands of points and sounds like tedium. [PlasmatronX] had a better idea: use Schlieren imaging to see the sound waves as the travel through the space. Schlieren imaging has trouble with audio frequencies, though, and imaging the entire living room was going to be difficult. So he scaled it all down– including the sound waves, by shifting to ultrasonic frequencies.

He’s using the usual mirror-and-razor Schlieren setup with an 8″ telescope mirror– and if you don’t know what that is, we did a deep dive on this kind of optical flow visualizer a while back. Inside the circular imaging area where that lets him see density changes, he’s set up what he calls a CAT– Computer Acoustic Tomography– array. It’s a rig on a turntable he can set up ultrasonic transducers on, to match the various speaker setups he wants to test, and turn so he can see from all angles what the scaled-down waves are doing. To capture those waves, which aren’t going to be standing still, he adds a stroboscope. All the ultrasound signals are being generated by a Pi Pico, and are scaled 4:1 in the frequency domain– that is, a high 10kHz whine becomes inaudible 40kHz. Those signals are fed through a DIY 8-channel amp into both ultrasonic transducers and larger ‘cat-repellent speakers’ from AliExpress.

The microcontroller is actually a Pico 2W, which is using its “W” to communicate via Bluetooth with a Pi 4. That SBC is running the camera, the stepper for the turntable, and image processing, along with the timing for the audio signals. After that it’s a matter of setting up a scaled down 7.1 surround setup and itty-bity soundbar, and test it on a (stuffed) guinea pig. Obviously you can see a big difference between the steered beams from the tiny soundbar and the true surround, but how that translates to listening pleasure will be at least somewhat subjective.

What’s less subjective is the obvious effect soft furnishings add to the simulation. Now he doesn’t take the time to find a material that will scale the frequency response of a set of curtains, but we’re not sure how much that matters. At 5kHz or 20kHz, they’re going to deaden sound, and you can see that here, and you can see it’s a much bigger deal for the shaped beams of the soundbar than it is for surround sound. In the end, [PlasmatronX] decides to stick to headphones, but the whole video is very much worth watching, so we’ve embeddded it below. If you want to try it yourself he’s put his code on GitHub.

Thanks to [PlasmatronX] for the tip!

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Smelly Ultrasound

November 24, 2025 by Al Williams 26 Comments

We aren’t sure why, but [Lev Chizhov] and some other researchers have found a way to make you smell things by hitting your head with ultrasound. Apparently, your sense of smell lives in your olfactory bulb, and no one, until now, has thought to try zapping it with ultrasound to see what happens.

The bulb is somewhere behind your nose, as you might expect. This is sub-optimal for ultrasound because your nose isn’t flat, and it is full of air. Packing a subject’s nose with gel wasn’t going to win many fans. The answer was to place the transducer on the person’s forehead and shoot down at the bulb. They made a custom headset that let them precisely target areas of the subject’s bulb guided by an MRI.

So far, they have a sample size of two, but they’ve managed to induce the smell of fresh air, garbage, ozone, and burning wood. What would you do with this? Smell-o-vision? A garbage truck VR game? Let us know in the comments. We don’t think this is exactly how the last VR smell gadget we saw worked, but — honestly — we aren’t completely sure.

Break The Air Gap With Ultrasound

June 29, 2025 by Jenny List 15 Comments

In the world of information security, much thought goes into ensuring that no information can leave computer networks without expressly being permitted to do so. Conversely, a lot of effort is expended on the part of would-be attackers to break through whatever layers are present. [Halcy] has a way to share data between computers, whether they are networked or not, and it uses ultrasound.

To be fair, this is more of a fun toy than an elite exploit, because it involves a web interface that encodes text as ultrasonic frequency shift keying. Your computer speakers and microphone can handle it, but it’s way above the human hearing range. Testing it here, we were able to send text mostly without errors over a short distance, but at least on this laptop, we wouldn’t call it reliable.

We doubt that many sensitive servers have a sound card and speakers installed where you can overhear them, but by contrast, there are doubtless many laptops containing valuable information, so we could imagine it as a possible attack vector. The code is on the linked page, should you be interested, and if you want more ultrasonic goodness, this definitely isn’t the first time we have touched upon it. While a sound card might be exotic on a server, a hard drive LED isn’t.

High Frequency Food: Better Cutting With Ultrasonics

March 21, 2025 by Zoe Skyforest 36 Comments

You’re cutting yourself a single slice of cake. You grab a butter knife out of the drawer, hack off a moist wedge, and munch away to your mouth’s delight. The next day, you’re cutting forty slices of cake for the whole office. You grab a large chef’s knife, warm it with hot water, and cube out the sheet cake without causing too much trauma to the icing. Next week, you’re starting at your cousin’s bakery. You’re supposed to cut a few thousand slices of cake, week in, week out. You suspect your haggardly knifework won’t do.

In the home kitchen, any old knife will do the job when it comes to slicing cakes, pies, and pastries. When it comes to commercial kitchens, though, presentation is everything and perfection is the bare minimum. Thankfully, there’s a better grade of cutting tool out there—and it’s more high tech than you might think.

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Hearing What The Bats Hear

February 11, 2025 by Elliot Williams 9 Comments

[Iftah] has been exploring the sounds beyond what we can hear, recording ultrasound and pitching it down. He made a short video on the practice, and it’s like a whole new world of sounds exists just outside of our hearing.

For instance, a dropped toothpick sounds like you’ve just dropped a piece of lumber, a broken lightbulb sounds like a shattered window, and a blackbird sounds like a blue whale. Besides simply sounding super, [Iftah] speculates that there’s some regularity here: that as you slow down the sound it sounds like it came from sources that are physically bigger. He follows this up in a second video, but if you just think about the basic physics, it makes sense.

If you’re interested in recording your own ultrasound, there are a bunch of options on the market. With modern audio processors running up to 192 kHz or even 384 kHz out of the box, all that’s missing is the high-frequency-capable microphone. Those aren’t unobtainable anymore either with many MEMS mics performing well above their rated frequency response specs. Recording ultrasound sounds like a fun and not-too-expensive project to us!

Of course, most of the ultrasound recording we’ve seen has been about the bats. Check out the Pipistrelle or this pair of DIY bat detectors for some good background. But after watching [Iftah]’s video, we’re no longer convinced that the cute little insectivores are the coolest thing going on in the ultrasound.

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