**Jamming Devices: A Review of AliExpress Audio Interference Solutions**

As a podcaster and YouTuber, I've always been on the lookout for ways to improve my recording quality and reduce interference. Recently, I came across some audio jamming devices on AliExpress that caught my attention. In this article, I'll share my experience with these devices and provide you with an honest review of their effectiveness.

**The Test: A Head-On Approach**

My first test was to point the microphone directly at the device, essentially having it "head-on" with the mic. I chose a few different microphones to try, including some MEMS mics and small condensers. To my surprise, most of them were defeated by the jammer's interference, producing no sound or a heavily distorted output. Even my trusty shotgun microphone, which I normally use, was not immune to the device's effects.

One notable exception was the Sanken Koss 11-D, a lav microphone that I often wear. Its diaphragm is rotated 90 degrees inside its tiny cylindrical housing, which significantly reduces the jamming effect of the device. Even with head-on testing, I noticed significant zigzagging lines on the spectrogram, indicating the presence of interference.

**Testing Other Microphones: The "45 and 90 Degree" Approach**

To further test the effectiveness of the device, I decided to try it at different angles. I placed the mic at 45 degrees and 90 degrees off from the source of the interference, essentially using them as shields between me and the jammer. To my surprise, this approach significantly reduced the impact of the device on my recording quality.

The Zoom H1N recorder, which uses two small microphones in an XY configuration, was also tested at these angles. While both mics experienced significant jamming, the one that wasn't pointed directly at the jammer picked up the voice quite well. This led me to test all of my mics using this approach, and I found that some were more resistant to interference than others.

**The Standout: The MKH416 Shotgun**

After conducting these tests, the MKH416 shotgun from Sennheiser stood out as a top performer. Not only did it handle the 45 and 90 degree tests with ease, but even when jammed half a meter away, blasting down the barrel, it was still able to pick up the voice clearly. As I pulled back to a meter, the jammer's effect on my recording quality disappeared altogether.

Looking at the spectrogram, I could see that the MKH416 was picking up what the jammer was throwing down, but not being significantly affected by it. There are likely several factors contributing to this effectiveness, including its relatively light diaphragm and the fact that the element is tucked away deep inside the mic behind an interference tube.

**A Silver Bullet? Not Quite**

While these devices are surprisingly effective against casual attempts at recording a conversation, they're no silver bullet. In reality, a determined individual could easily hide a heavy diaphragm mic up in the ceiling over the conference table and catch me off guard that way. The device's effectiveness is largely dependent on its size and proximity to the source of interference.

**Conclusion: UPDF and Productivity**

As with any device that claims to solve a problem, there are pros and cons to consider. In this case, I've found that these audio jamming devices can be surprisingly effective against casual attempts at recording interference. However, they're not foolproof, and it's essential to test them thoroughly before relying on them for critical recordings.

If you're looking for a reliable PDF solution with a clean UI, UPDF is definitely worth checking out. With its ability to handle PDFs across multiple platforms, edit elements quickly, and even merge or split PDFs, it's an excellent tool for productivity. Plus, its AI features offer advanced functionalities like summary, translation, and explanation. As a bonus, you get up to 100GB of cloud storage across all devices, making UPDF an excellent companion for anyone looking to improve their workflow.

And if you enjoyed this video, be sure to check out my next project – building custom AliExpress headphones for Dankpods! It's been a fun and rewarding challenge.

"WEBVTTKind: captionsLanguage: enYou know what society is like these days.If I just come out and say,and that sound bite hits the internet, boom, can't.And with the number of people working here,that would be a pretty rough dayfor a lot of hardworking families.But guys, I gotta be me.And if I can't loudly proclaim that...then how could I even drag myselfto the office every morning?That is where this little guy comes in.It discreetly prevents your conversationsfrom being recorded on someone else's phone,hidden microphone, or voice recorder.And as you can tell when I say, I don't know...It even works against the professional lavalier microphonethat I'm wearing.It's not perfect though,and it comes with some serious downsides.So before you trust your most intimate secretsto one of these bad boys,you should probably watch past this super edgy segueto our mother F*** sponsor.Ugreen, their Nasync DXP480T+comes with a 12th gen Intel processor,eight gigs of expandable DDR5 memory,and dual Thunderbolt 4 ports.Plus, its onboard AI assistant makes file management a breeze.Check it out at the link down below.The marketing images for the F11 anti-voice recording,bug wiretapping, audio 37,emission hole of ultrasound,interference anti-eavesdropping spy deviceare a gold mine of dubious claims.The recording terminator, 37 launch heads,anti-voice recorder recording.It even claims to have anti-video recording.Ah, here, let's try it.Can you guys see me when I flick the button?Okay, well, that last one seems to be nonsense,but how does it disrupt the sound recordingthe way that it does?Is it just blasting out white noiseso loud that you can't hear me?No, because believe it or not,when you guys are hearing thatmess from the jammer,none of us in the studio are picking that up.We can all hear each other just fine.I can hear it.Okay, but you have headphones on. Let me explain. Many of you willalready know howmicrophones work. Here's a microphone shaped like a cookie. Goodjob. But foreveryone else, the TLDR is that they typically contain a thinmembrane calleda diaphragm that gets vibrated by incoming sound waves. Thatvibration isturned into an electrical signal, amplified, and the rest of thedetailsdon't really matter for now.What does matter is that a microphone's response to differentfrequencies of vibration is non-linear,meaning that it varies from high-pitched noises to low-pitchednoises.This weakness is what jammers like this one can take advantage of.By blasting out sound waves at frequencies that are higher than thetypical human can hear, they canshake the mic's diaphragm around like crazy in the frequencies thatwe can hear and make it impossible for a hidden mic to pick up mysecret confessions.We're gonna link a couple of papers in the description if you wantto get into the math for how it works.But for now, let's look at this clip that we recorded earlier witha calibrated measurement microphone. Wow!Just from looking at the waveformit's pretty obvious where the jammer turns on and where the jammerturns off.But what's happening at the different frequencies?This right here is a spectrogram and it visually representsthe intensity of sound waves in each frequencyfrom zero Hertz at the bottom,all the way up to 90 plus kilohertz up top.The brighter the display,the more intense the sound waves are at that frequency.Let's blow this up though and take a closer look.We mere humans can typically only hear sounds inabout this range right here,from zero to 20 kilohertz or 20,000 hertz.Of course, that's when we're youngand it tends to narrow as we age,especially at the high end.But as you can see over here,that's not really that big of a dealgiven how much of human speechtakes place within that range.Of course, once the jammer kicks in,you wouldn't have any chance of making out any soundswith this level of intensity with all of this noise.This still doesn't tell us the whole story though.And hence,let's zoom in on just a second or twoof our jam section here.You can see right here is where our jammer turns on.All of the high intensity sounds are being generatedabove that range of human hearing.But by choosing specific intervals,they're able to induce vibrationsthat spread to cover the entire spectrum.Andyou can see that once you've got this much noise, it's basicallyimpossible to make out regular human speech.And it's not just our crappy meat ears that are defeated by this.Check this out.I've got a speech-to-text app on this phone and with the jammerturned off, the app does a pretty respectable job of transcribing what I'msaying.But as soon as we turn the jammer on...And the AI would have no ideathat I just confessed one of my deepest, darkest secrets.So that's it then.Video over, everyone go buy one of these.See you later.No, not quite.You see, the advertising heavily featurescorporate boardroom type use cases for it.So to validate that, we set up our jammerin our meeting room and ran a few experiments.Starting with probably the least realistic scenario,where our recorder here isn't trying to hidewhat he's doing, the jammer works admirably.But that's not a huge surprise.Even AliExpress specials like this onerarely completely don't work at all.What was a surprise though,was that we almost exploded Elijah's headthe first time that we turned it onand he didn't have any hearing protection.Ok. Its really agressive.As it turns out, just because most mere mortals can't hear what'scoming out of the jammer,some can, and some especially can. For this reason, while deviceslike this are legal here,as far as we can tell, we have no data whatsoever on the long-termhealth and safety effects ofusing a device like this, and their use could be either dangerous,or restricted by your local government. So your mileage may vary.On that note,let's turn our attention to a more realistic scenario where atleast one of us,Colin, at least one of us is trying to hide what we're doing.Our spy now has his device on his lap under the table. And since wedon't trust each other,I probably don't want him to know that I have this jammer. So I'vehidden it next to thispotted plant.What, it's a common plant, the cactuar.I just activate all three switches,so we're blasting out in all directions,and then I can say.Regardless of the hiding spot,the result ended up being about the same.There's enough noise bouncing around in the roomto mess up the recording.However, if our target is sensitive to high-pitched noises,like the whine of an old tube TV,they're likely to know that something is amiss,andif our spy tries to get even a little bit sneakier by tucking theirrecording device under their clothing, especially under a couple of layers ofclothing,well, watch this, guys. I'm about to reveal that Nate killsDumbledore!And there's nothing anyone can do to prevent me from being ana**hole.Any questions, Colin?Sure.The point is, it turns out that, again,regardless of the relative positionsof our recording device and our jammer,a couple layers of cloth are so effectiveat blocking these super high frequency noisesthat they do a remarkable job of reducing its effectiveness.Which got us thinking, up until this point,all the mics we've tried have been tiny,either literally tiny.Like these MEMS, or Micro Electro Mechanical Systems Microphones,like you would find in a phone, a voice recorder, or a smart home hub.Or figuratively tiny, like the small diaphragm condenser that youwould find in the measurement mic, or my lavalier.These two types work a little bit differently from each other, butwhat they both have in common is tiny, thin diaphragms that are easily bouncedabout in the ultrasonic storm that's created by the jammer.But of course, there's a lot of other types of microphones.So we rounded up a bunch of examples,laid them out and managed the cableswith our new magnetic cable management from lttstore.com.Each mic was tested at the same distancewith the mic pointing straightat the business end of the jammer.And what we found was that it was quite effectiveagainst most of the MEMS mics and small condensers,even including our shotgun microphone, not.Every mic was defeated, however, and our first surprise was theSanken Koss 11-D,which is actually the lav mic that I normally wear.As it turns out, its diaphragm is rotated 90 degrees inside itstiny cylindrical housing.So even head-on, the sound waves from the jammer weren't actuallyhitting the diaphragm in adirect path, which significantly reduces the jamming effect. If wecheck out the spectrogram,there's none of those zigzaggy linesthat we saw before at all.Another one that was interesting was the Zoom H1N recorderthat uses two small microphones in an XY configuration.And we found that while both did experiencesignificant jamming, the one that wasn't pointed directlyat the jammer picked up the voice quite well,which prompted us then to test all of our mics,either 45 or 90 degrees off of the sourceof the interference.In addition to our head-on tests.So our final standout then after those tests ended up beingthe MKH416 shotgun from Sennheiser.Not only did it handle the 45 and 90 degree testslike a champ, but with the jammer half a meter away,blasting down the barrel, it was jammed.And then as soon as we pulled back to a meter,it was like the jammer wasn't even there.Looking at the spectrogram, we can see it is picking upwhat the jammer is throwing down.But it's not having a significant effect on the diaphragm at otherfrequencies.We think there's a combination of factors that are likelycontributing to this.While the shotgun still has a relatively light diaphragm, if I wereto compare it toa dynamic stage mic, for example, it's still larger and heavierthan the other small condensersthat we tried, making it a little harder for the jammer to abuse,especially as the mic getsfarther from the source. Also, the element is tucked awaydeep inside the mic behind this section called the interferencetube, which basically makes themic more directional, especially as the frequency gets higher. Theresult is that less of thosesuper high frequency waves from the jammer are going to bounce allthe way down the tubeand mix together to mess with our recording. But as good as it is,it was no match forlarger diaphragm condensers or dynamic microphones like thevenerable Shure SM58or our broadcast quality RE20s from The WAN Show.So in conclusion, yeah, it works,but it's not the silver bulletthat the advertising would have you believe.Pretty typical AliExpress.Against a casual attempt to record a conversation,it's surprisingly effective,but it should be noted that it makesa pretty unsettling noisethat kind of feels like pressure on more sensitive earsand also realistically.A ne'er-do-well could easily hide a heavy diaphragm mic up in theceiling over the conference table and catch me off guard that way.Then again, if they've got that kind of access to the building,they could probably just take me out directly instead of waitingfor the pitchfork-wielding mob.So, I guess I'll just have to keep my controversial opinions aboutwhether Quebec should just leave the country already.Oh, damn, it was off.To myself, for a little while longer.But I'll happily tell you about our sponsor:UPDF!UPDF is a simple PDF solution with a clean UI for all your PDFneeds.It can handle PDFs across the most popular platforms, from Windowsto Mac to iOS to Android,all with one UPDF account. 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