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Comment by bscphil | Hacker News Reader

> A large, somewhat ungainly white cuff with spiky transducers, the bracelet has 24 speakers that emit ultrasonic signals when the wearer turns it on. The sound is imperceptible to most ears, with the possible exception of young people and dogs, but nearby microphones will detect the high-frequency sound instead of other noises.

This is surely not actually effective against a wide range of well designed, real world microphones, and definitely not against something designed to surreptitiously record you. Strikes me as more of a gimmick than anything else.

Full disclosure: I don't have any always-on microphones in my house, and probably never will, so I probably qualify as some kind of techno-skeptic.

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> I don't have any always-on microphones in my house, and probably never will, so I probably qualify as some kind of techno-skeptic.

That you know of. Every smartphone has a microphone, as do most laptops and desktops.

any visitor to our house has to put their phone into a key box next to the entrence which is shielded. it is both annoying and confusing for them the first time they visit. but I guess for them it is also a bit exciting ("what kind of a looney place did we agree to come to") ... but it makes for great conversation ... the purpose for us is less security/privacy but a way to teach my environment about these problems. It also makes for interesting conversations around screen addiction, anxiety and spending time in the moment.

We still use wireless/laptop ofc and when we are among ourselves we have a rule that the phone goes in the box from 18:00 - 06:00. but for visitors there is no cell-phone in my house (this is perfect for us because we can pretty much rule out microphones/cameras being used).

I understand this might sound very strange for most people here, and it is strange. But how would you feel if say in the 80ies and 90ies you invite somebody for dinner and they show up with a big camera/flash around their neck and a microphone and tape recorder.

bienvenue chez moi!

also my partner does use a mobile phone for work, or on the go. I don't own one.

I think you should go one step further and after they reluctantly agree to put it in "the box", it proceeds to smash it with a hydraulic press clearly visible through a pane of glass on the front. Of course, you don't actually smash their phone, but a dummy you substitute with sleight of hand. Oh, but the look on their faces!

Ha that is really mad. Going to save this comment as an example of how atypical HN readers are!

You put off your coat and shoes when you enter my house, but not your spycraft? Not that I follow the same rule, but when I think about it, I find it entirely reasonably. It is the rest of us who, including myself, who are mad.

Most people consider the likelihood of things actually happening. It is not likely that MI6 are listening to my phone or any of my friend's phones, and even if they were the worst that happens is they hear my boring conversations. So for 99.999% of people the benefit is essentially zero, and the cost is moderately high (having to put your phone in a box all the time).

Consider other things that have a similar cost/benefit ratio that are more obviously mad:

* I could install a 3 metre high wall with razor wire around my house in case the police try to attack me for some reason.

* I could walk everywhere wearing a bicycle helmet in case I fall over.

* I could never use stairs. Only use lifts - they're much safer!

Hopefully it's obvious why those are mad.

I hope you never witness a government official breaking the law and start thinking about blowing the whistle.

It isn't the local secret service we should be wary of (they can already easily get access anyway); it is commercial companies who profit of data, and hostile secret services.

Sounds incredibly inconvenient. What if your guest is expecting/gets a phone call that day? Or they want to show you some holiday pictures? What about smart watches?

I'm really conflicted, as your approach is privacy focused but I just can't imagine following it in real life. Perhaps I'm part of the problem...

Wonder what is your opinion about hearing aids. Many modern ones broadcast everything via radio because of stereo processing. It's strictly proprietary and impossible to get any further information from the manufacturer.

If you ask their wearer to put them away before entering, then you can't have conversation with him/her.

This behaviour is not only unhealthy, it's also unnecessary. What precisely do you hope to gain from this? Do you truly think that you're really depriving any observing agents of knowledge that they desperately hoped to gain? I could understand protocall like this for mental health reasons, or for the desire to be "free" from technology for a time, but you can't justify this behaviour purely with privacy concerns. They already have more than enough information on you from the remainder of the time that you spend with your device(s).

> This behaviour is not only unhealthy

you misunderstood. privacy is the conversation opener but discussions around mental health are the goal. when you say it is unhealthy are you implying "devices on the dinner table are healthy?" or putting toddlers on a screen/ipad is healthy? or showing your kids that it's ok to be only half present when interacting with them is healthy? sorry I utterly missed your point.

Why unhealthy? Having rules for guests which make you more comfortable in your own home makes sense to me.

Parent stated ‘the purpose for us is less security/privacy but a way to teach my environment about these problems.’

Seems more like daily Sabbath.

Sure they can justify that behaviour. It is their house after all, and they set the rules. Period.

That you know of also ;)

Many privacy-concious people opt for software that allows them to verifiably control their hardware, be it desktop/laptop or smartphone.

Some will go the extra step to physically remove or disable microphones and speakers.

> Many privacy-concious people opt for software that allows them to verifiably control their hardware, be it desktop/laptop or smartphone.

I know a fair number of privacy-concious people, and not one of them have any sort of verifiable control of their hardware. It's surprisingly hard to do this, it turns out…

> I know a fair number of privacy-concious people, and not one of them have any sort of verifiable control of their hardware.

I have a reasonable level of confidence that my use of wirecutters and/or soldering iron gives me enough control over this kind of thing. It's impractical on a smartphone, but I solve that by not owning one.

verifiably?

A synonym for "open source".

Open source would only be the start: you still need to build or forensically audit each component (hardware or software) or you’re fooling yourself.

Reproducible builds.

I know more than a couple of older people who can still hear very high pitched whines from electrical equipment. The “only children and dogs” is some bad statistics.

Also houses have dogs or kids. Or both. It’s a thing.

I used to be able to hear monitors whine and I'd have to unplug them completely. Can't anymore; I thought it was because I was getting older and my hearing at the higher frequencies was dropping off. Still got one of the monitors I used to be able to hear whine and I can't hear it anymore.

Seems odd that there are older people who can hear the high-pitches when younger people can't. Maybe the kids are tuning it out.

I’m a bit older than average and these types of things and noises drive me crazy. I can’t even be near some old CRT screens due to the pitch they emit (especially bad with old CCTV monitors).

I may have lost a little at the high end or electronics have gotten better filters, but I used to grumpily stomp into the next room to turn off the tv or the VCR because it was bugging me.

There was a story a few years back about stores getting rid of young loiterers by playing these tones, then later on kids setting ringtones or alerts on their phones so that the teacher wouldn’t get mad that their phones were on. Guess what? A lot of surprised 15 year olds had their phones confiscated by disgruntled 40 year old teachers who could damn well hear the ringtones.

The TV noise you used to hear is gone because CRTs are gone-- it comes from the flyback tranformer in the TV, which had a propensity to resonate at the TV's horizontal scanning frequency (somewhere in the ballpark of 15.7 kHz, the exact frequency depending on whether your TV was NTSC or PAL).

I had a "I haven't heard that in ages" moment over the summer; was in some shop in the UK that had a CRT showing their CCTV cameras and could hear the thing well before I could see it. Apparently my high-end hearing's still decent.

CRTs are almost gone; they’re still highly sought after in the smashbros community. :-) IIRC trinitrons are the most highly desired.

Due to the shortage, a "crt vault" was created. [0]

I remember visiting multiple thrift stores ~2 years ago to collect them. The most I had was 6 I think, but I ended up giving them to other players. Here's an example of what they look like at tournaments [1]

[0]: https://old.reddit.com/r/smashbros/comments/3dzqd9/to_those_...

[1]: https://www.youtube.com/watch?v=j_WBBeXzUcQ

The other day my dad, who turned 60 last year, swore he couldn't hear a cicada that was right outside the open window. It bugged him so much he made me go outside with him and point out the cicada. I told him about the mosquito tone, which is obviously much higher, and how mostly only younger people are meant to be able to hear it and played it for him off Wikipedia. He could hear it fine and so could I (30 this year). To hell with the mosquito tone as an anti-loitering device, it's horrible.

Like those high-pitched 'mosquito'-devices installed in places where young people tend to hang out; most adults over 25 can't hear them at all. There is a school here with an apparently inviting set of steps under an awning that activates this device outside of school hours. Passing that building is really annoying.

I'm 39.

Oh God, I saw one of those in Japan outside a store at night, we came near it and I went "what the hell is that noise?", but none of my friends could hear anything. Turned out to be the mosquito thing, which was quite effective in getting me away from that shop.

I was 35 at the time and my friends were 30ish, I guess it varies by person.

It's the babies brought into the shops by their oblivious parents that I feel sorry for. Mosquito devices ought to be illegal, it's noise pollution.

> Full disclosure: I don't have any always-on microphones in my house

Does this include smartphones, computers, or other such devices capable of becoming always-on microphones in software?

It's an one off art project, not an actual product they're aiming to start selling. Of course it's a "gimmick", that's not the point.

Dolphin Attack used ultrasonic amplitude modulation against a variety of devices with some success [0]. Page 9 for the results table.

I believe they were taking advantage of the non linearity of microphones.

0: https://arxiv.org/pdf/1708.09537.pdf

I suspect that it would only work against MEMS microphones. Normal "analog" magnetic microphones physically filter high frequency noise.

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