Seen this viral tweet about a portable audio jammer? Looks cool, right? It also looks quite similar to 100s products sold on Alibaba & in spy shops for years. Or as DIY kits for $50 in parts. They use ultrasonic noise to overwhelm very close-by microphones. I'm skeptical about the price tag & way it's being marketed, and I'd like to share why: it seems to me that what differentiates this, aside from the privacy-aligned language, are claims that sound to me like they've developed "novel physics" & use AI to detect microphones. This would be extraordinary and would require equally extraordinary proof if true. I suspect that the reality may be more like using WiFi etc to scan for devices. This is not novel physics. The problem: many of the microphones that people are most worried about don't emit wifi or bluetooth etc. Or could be a phone in airplane mode. Etc. Additional issues around ultrasonic jamming? Complex range limitations, issues with room reflections, fabric absorbing emissions from your jammer, obstructions etc.. A phone in a fabric pocket might not be defeated by this device reliably, for example. Critically also: the range of this kind of tech is the distance between the emitter and the microphone. Not between you and the unwanted microphone. So if you are in a normal size room and the microphone is, say, 3 meters from you in the ceiling, or on the other side of the couch, it might well still hear you clearly. Consider asking your friendly local expert in audio, physics, or security before purchasing or investing in this product. I'm not one of those. Source of my understanding: I spent some time a few years ago planning to assemble such a device and read a lot of papers. I may be wrong in my understanding (or missing something!) and would happily correct if I've misunderstood what they are offering. To learn more about this popular and well-known category of object, watch @LinusTech from a year ago

3/ I'm especially concerned because the product @aidaxbaradari is promoting uses the kind of language that (if it ships & people use it) may lead them to think they are fully safe from eavesdropping. When they may not be at all. I urge very strong caution unless the more exceptional claims are substantiated with clear technical evidence.

4/ Founder replying to someone else about microphone detection with a troubling answer. Reason: Microphone circuits typically generate NO significant RF emissions.* You can't passively detect even a basic resistor circuit on a board from a distance by RF scanning the way @aidaxbaradari is describing * I would love to hear any microelectronics engineer weigh in here. *For you fellow obsessives: a technology for identifying circuits exists, but it is very different than RF scanning. It's called a Non-Linear Junction Detector. The NLJD first emits out a powerful, very local, high frequency RF signal and then watches for harmonics produced by the interaction of the RF with semiconductors. The working distance for this is very, very limited.

6/ The founder again responded but is not addressing what I see as the core question around identifying microphones. Founder promises a video explaining technical details. I promise to update if I've misunderstood something here, but I remain concerned & I think you should be too. I want to be clear at this point: ✅using ultrasonic energy to mess with the membrane of microphones does work with many limitations and is known (see below) But what really concerns me: ❌claims about identifying microphone circuits with RF, for example, that do not match what I believe to be consensus knowledge of electronics or RF. There are many reasons it that the tech is not more widely used in classified & secure spaces. Like potential harm to your eardrums that you can't perceive when the device is running at a volume necessary to achieve the messing-with-microphones (ouch!) but pets might (ouch!).

6/ The founder again responded but is not addressing what I see as the core question around identifying microphones. Promises video explaining technical details. I want to be clear at this point: ✅using ultrasonic energy to mess with the membrane of microphones does work with many limitations and is known (see below) Key limitation: There are many reasons it that the tech is not widely used in classified & secure spaces. One example: potential harm to your eardrums that you can't perceive when the device is running at a volume necessary to achieve the messing-with-microphones (ouch!) but pets might (ouch!). But what really concerns me: ❌the claims about identifying microphone circuits with RF, for example, that do not match what I believe to be consensus knowledge of electronics or RF. I promise to update if I've misunderstood something here, but I remain concerned & I think you should be too.

7/ Lets highlight some concrete stuff about why ultrasonic jamming isn't already a popular thing even though you can buy them everywhere online: -Either they are safe but likely useless beyond 1m. -Or, they are useful but likely harmful to you. PLAIN LANGUAGE: First, think about how loud the background noise needs to be before you *cannot understand* someone talking to you at 2m away. Very loud, right? Think about what kind of noise a device would need to make before you can't hear someone talking to you up close. Like fire-alarm / ambulance siren levels and above, right? A device trying to use sound to overwhelm a microphone is likely going to be absolutely screaming to achieve a desirable sound pressure level, even if that sound is happening in a range you can't hear. PHYSICS REALITY: From some past papers on this, I think you you need 110-120 decibels of ultrasonic pressure arriving at the unwanted microphone to trigger the disruptive nonlinearity in microphones you need to make speech unintelligible. But since sound decays via inverse-square law every time the *distance between your jammer & the microphone doubles,* you lose 6 decibels. The reason the distances are small is because to jam at 3 meters for example would require your jammer to emit almost impossibly high levels of sound waves. To make that kind of sound continuously you need powerful amplifiers. And you'd zip through a battery pack pretty quickly. Oh, and is the microphone recording you behind some fabric like a pocket? Again, huge power loss shown in the literature. Maybe requiring you to 10-100x your sound output. There is already research about the biological effects of loud noises that you can't hear. And the signs are not good for your health or for pets, which have much lower thresholds for damage. WHAT ABOUT NEW TRICKS THO? I want to be humble: I'm not an electrical engineer or a physicist working on sound. There is some active research going on in this area and I'm not one of those researchers. So please ask one before making any big decisions around this tech. Still, even if novel modulation tricks exist (like using multiple frequencies, trying to create specific messy harmonics, trying to mess with noise cancellation algos etc) they CANNOT GET AROUND around inverse-square decay, fabric & obstacles. There is also substantial variability in microphones & signal processing across devices (noise cancellation, beam forming etc) that would seem to make it hard to be absolutely sure you could guarantee a product would reliably jam a broad spectrum of devices it can't identify. This is why I've been asking the founder questions about microphone identification & why it matters. If the the claims are that this device does something fundamentally different, reliably, then it would need to provably do so for an impossibly large set of potential microphones, phone configurations, noise cancelling algos, multi-microphone arrays on phones etc. Thanks for following along. I hope you found this useful. I promise to add corrections etc if there's something I'm not picking up here about the product or the claims.