Hacker News Reader

Comment by zapperdapper | Hacker News Reader

Interesting one. I remember I went to the local One Stop with my son - he was about 15 at the time. He couldn't bear standing outside - he said the noise was unbearable. I said "what noise"?

Apparently they used some kind of sonic device that emits sound that can only be heard by teenagers, and it was incredibly effective - they wouldn't hang around outside the shop more than a moment longer than necessary. I do wonder whether it caused any damage though?

One Stop was later bought by Tesco and they got rid of it.

View on HN

That's the Mosquito Anti Loitering Device

http://www.movingsoundtech.com/

It a high frequency that only young ears can hear that sounds like the whine of a mosquito. Old ears lose frequency range so aren't bothered. It's not harmful, just annoying.

These devices still bother my ears even at 37.

Same here, we encountered one in Tokyo and I had to run away. My (younger) friends all thought I was crazy until I sent them the link to the device months later.

That was my son's reaction - he couldn't get out of there fast enough!

At a sufficient volume, the sound would be damaging the ears even if it's above the frequency that you can hear.

Hopefully they'd make it so even cranked to 11 it couldn't hurt anyone.

For a manufacturer it's not as cut-and-dry. The damage caused is a factor of the level (dB) received combined with the length of exposure. Assumptions will have to be made as to how far away the user will be from the device and how long they can reasonably be expected to be exposed.

For example, if you assume that someone will be under it for 8 hours (an employee during a work day), the OSHA approved exposure is 90dB, which will likely not be annoying enough to serve its purpose.

90db is pretty loud and will totally wreck your hearing, which makes the situation kind of messed up because workers might not even know they're being exposed to this sound.

That doesn't seem physically possible since it's based on sound pressure waves.. From your link, mk1 uses 85 db set volume; mk2 uses ambient noise level + 5db.

It's disgraceful to use such a device that deliberately targets the young. I can hear it and it's a annoying as shit and I'm 32. AFAIK they have now been thankfully been banned in the UK/Ireland.

In London, TFL has found the same effect can be hard without some discrimination by playing classical music.

That will drive off the young street punks. But instead you'll have a bunch of old codgers setting up their checker tables, hanging out for hours complaining about their problems, and pining for the good old days.

That's my retirement plans anyway.

I (31m) can hear high frequencies

- Last night, an ecigarette's capacitor/resistor (from 20 feet off)

- Home Depot has high frequency bird detractors

- A friend has a heart condition and a phone addon to help manage it.

- TVs w/ bad speakers/signals/lighting

- Some fluorescent lights.

The worst part is that it hurts, it's like nails on chalkboard you feel it inside when it happens, almost debilitating, and definitely hurts the balance.

35 here. I can still pick up the flyback transformer whine of a CRT, electronic fluorescent ballasts (really horrid in the induction ones) and inverters in laptops/LCDs using CCFL backlighting. It used to not be so bad, but then people stopped potting their coils in the name of saving money...

Wow! that comment takes me way back to when I could tell a CRT was about to go bad because of the sound of the flyback transformer leaking ! :)

A few years back I had a monitor at work where I complained to my boss that it was emitting a high pitched whine. I was about 10 years younger than anyone else on the team, and no one else could hear it. The PC technician I called to look at it couldn't hear it. Needless to say it didn't get replaced, that is until we got a summer intern. The first time the intern walked past my desk she asked "how can you stand that sound?" and I had her go to my boss to say the same thing. My boss got another intern from another team to listen and confirm, and I got a replacement the next week.

It's one of those sounds you can never drown out, it's such a unique frequency.

Advice for next time: you don't have to depend on a human's word. You can use a real-time analyzer [1], now available in smartphone apps. They display the frequency spectrum of ambient noise.

We had a similar situation at our office, were the smoke detector was emitting a steady whine that only a few employees (including me) could hear. One skeptic was finally convinced by getting out an RTA app and seeing the big spike at 12 kHz.

[1] https://en.wikipedia.org/wiki/Real-time_analyzer

Wow, 12 kHz is not audible to most adults? That's pretty surprising.

I don't know the percentiles by age (it's hard to find from googling). Just saying that that one fortysomething adult couldn't hear it.

When I checked this, as a fun experiment to do with kids (they love "winning" this game, after all), is that yes while I'm technically able to hear 15-16 kHz, there's a very steep drop-off in sensitivity already quite a bit below that. I needed to turn up the volume on a pure sine-wave quite high (which the kids hated immediately) to be able to hear it somewhat clearly.

So if you add in ambient noise (in lower frequencies), that could plausibly drown out a 12 kHz noise very well, for older adults (I'm mid 30s myself).

Interesting side-note: Turns out that the low end drop-off (at about 20-25 Hz or so) is not very age-dependent at all (at least when I tested these "against" a 13-year old's hearing). You need quality headphones for this, most speakers will distort/resonate some higher frequency harmonics, which you can always clearly hear. It was very interesting to hear something that was clearly a very very low frequency tone turn into a sort of rapidly fluttering/beating sensation at the cross-over frequency, you can feel it beating slightly on your eardrums, but it doesn't translate into a "tone-like" sensation any more.

And yes we made sure to not do it for more than a few seconds, to not accidentally cause hearing damage--though with good closed headphones we didn't need to turn it that high, as the effect wasn't so much that the perception of the tone "disappeared", rather change into a different type of sensation.

Should have tried changing the refresh rate.

I'm the same way...cheap phone chargers, etc

- CRT tvs/monitors

- This battery charger for a drill I have

Some TI-83 calculators are audible, mostly for special keys like "programs", "apps", and maybe "clear" if memory serves.

I'm the same way.

In middle school, I was sent to the principal's office because I complained to the teacher about a painful noise and the teacher thought I was just being disruptive. There it was determined that the "silent" alarm had gone off.

I also get it when touching some glass surfaces as there's a high-pitched squeak. My parents just accused me of trying to get out of doing the dishes.

Watching the movie 'Baby Driver' was torture. In his attempt to convey to the audience what it was like to live with tinnitus, the director made the film nearly unbearable to people like us.

There's just so many instances where people who can't hear these frequencies ignore the consequences for those that can. And then they disbelieve that anyone's hearing is substantively different than their own.

Interestingly, my tinnitus IS that sound. I can hear up to about 17 kHz and it is still higher than that. Which sucks, since all the available retraining and masking techniques assume you must be able to hear within the range of your T.

Your friend had something like an AliveCor Kardia and you could hear it?

Male, 25, can hear cheap phone chargers and on my crappy old Windows laptop I don't need the CPU monitor to see if it is loaded - just gotta listen and I hear the whine of the CPU voltage regulators. Even worse are old-ish laptop chargers in quiet environments.

https://en.wikipedia.org/wiki/The_Mosquito

Teens also have used this frequency as a ringtone in class as most teachers couldn't hear it.

The cell phone ringtone didn't make sense to me when people started using it. Sure, the teachers can't hear it, but they can see an entire class wince simultaneously.

Plus, there's a lot of teachers in their 20s who can hear it just fine.

The whole class may have winced, but I guess it'd be harder for the teacher to pinpoint where the sound came from.

There's no reason to wince - it's just a sound. The wincing is caused by the volume.

Perhaps it was a flinch? I find the tones on this site I found[0] highly unpleasant to listen to at any volume. The ringtones I was hearing were no louder than any other, but I know I recoiled on hearing them.

[0] https://www.ultrasonic-ringtones.com/. Unsurprisingly, I can't hear above 17k anymore. I'm not terribly upset.

In my high school, very strong peer pressure was applied to anyone who tried this as it was generally considered excessively annoying.

For my part, I used a Morse code ringtone that happened to sound similar to the howling noise the radiators made, which everyone had learned to simply tune out.

At Oval Station (next to the cricket ground), they have an entertaining anti-loitering strategy: they play classical music. I seem to be immune to its deterrent effect, though.

I have heard one of these in San Francisco, CA in the USA. The music had a really high pitched note behind it that sounded horrible.. like a cross between a mosquito and the buzzing of an input jack

If anyone's curious about their hearing range, try the example sound files here:

http://www.noiseaddicts.com/2009/03/can-you-hear-this-hearin...

14khz here :)

I find it hard to pinpoint. 14kHz is pretty clear, 15kHz very faint and 16kHz gets uncomfortable when I turn the volume up but otherwise not really audible. Anything beyond that I only hear the clipping at the start and end with nothing in between.

16 KHz clear but annoying. Nothing at 17 kHz.

18khz, I'm 21

Keep in mind that it's a common misconception that if you're exposed to noise or loud music, you'll lose hearing at the highest frequencies first. Hearing loss due to noise exposure tends to be centered around 4 KHz ("noise notch") -- you lose the higher frequencies with age (presbycusis).

Of course normal computer headphones or speakers aren't a great test for this, since their frequency response rarely goes that high. Especially the samples >20kHz, since that's beyond the normal range of human hearing. Even high-quality headphones won't play high-frequency sounds, the -3dB (half power) cutoff is generally about 20kHz. Having it higher can allow the headphones/speakers to produce unpleasant harmonics, so good devices are built to damp out such high-frequency resonances.

Commonly known as "Mosquito alarms" they emit high frequencies that adults have lost the ability to hear. I've never read a study that showed they cause permanent hearing loss, especially in adults, but it's unlikely someone would be exposed to them for long (vs the hypothesis here, that the diplomats were continually undergoing exposure).

That's not high tech. That's literally just a device constantly emitting a high pitched beep.

As you grow older, your hearing degrades. Especially if you subject yourself to loud noises or loud music (e.g. almost any live concert). The beep the device emits is just outside the hearing range of most adults (kinda like the hum old CRTs sometimes gave off).

Unless it's extremely loud it won't cause any damage, and it's less harmful if you can't hear it (because not hearing it means your ears can't pick it up in the first place) but I wonder if there are concerns about noise pollution.

Reply on news.ycombinator.com