High Frequency Kid Repellent

[audioguru]

The Dark Side Of The Moon by Pink Floyde starts with a 16Hz heartbeat and it doesn't make anybody poop. I played it full blast many times and no poop.

Even the Mythbusters couldn't make poop.

 

[Gaston]

i thought the frequency was a little lower around 5 to 8 Hz

 

[HarveyH42]

So, if myself and my baby go into a protected area, who should get the pain, me or my baby?

Mike.

Where did the origional post, or anything I posted mention pain? It's the annoying sound of an insect buzzing around, and the unpleasant memories of itching bites.

If this device actually caused pain or physical discomfort from just passing through the area, wouldn't that kind of scare off the paying customers as well?

 

[Blueteeth]

I would also like to see it banned.

To say 'only children can hear this frequency' is ridiculous. Women tend to be able to hear higher frequencies better than men as well. And the effect isn't limited to 'conscious' hearing. You may not be able to hear it, but many could certianly 'detect' it. After all, you could hear 50Khz if it was loud enough.

I'm 26 and I can just about pick up on a 21Kz tone, if its pretty loud. Whether or not I 'hear' it, is for another post, but I can certainly tell if its on or off.

Perhaps I've missed some vital specification for this device, but it seems to me its been pushed through without proper testing. High frequency sound has been used in the past, as well as infra-sound. Both had unwanted effects (or in this case, wanted?) causing nausea, dizziness, loss of conciousness and visual disturbances. Perhaps if this did indeed only effect 'children' or 'teenagers' then one of them may stubble into on-coming traffic. There would be a backlash, and they would be removed.

Once again the government brushes another problem aside claiming 'technology!' is the answer. As an engineer I would love to believe that is true..but lets face it, it ain't. Its the easy way out that will cuase more problems than it solves.

Blueteeth.

Ps. wow didn't realise how much I hated that idea!

 

[Hero999]

People can actually detect ultrasound up to 200kHz but that's only underwater and at really high levels. The reason why this is possible is not fully understood but the most likely theory is that the inner ear acts as a low pass filter which is by passed when the subject is underwater and the sound is at a high enough level.

The device isn't designed to be used continiously but only when children start to congregate.

Older people might be able to hear it too but it might not sound loud enough to be annoying.

Women generally live longer than men so perhaps they age a bit more slowly meaning their hearing may stay sensitive to higher frequencies for longer.

I've experimented with ultrasound before and found that sometime I thought I could hear up to 100kHz but this was explained by subharmonics and the ultrasound exciting other lower frequency resonances in the transducer and housing.

I'm 25 going on 26 and can probably hear up to about 16kHz to 18kHz depending on how I've aged considering that I had a hearing test at the age of 16 and my hearing was off the scale.

I don't know if it would bother me personally but I still think this is a really bad idea.

What about people who have hearing aids?

Could it generate subharmonics in them causing them to emit a loud low frequency noise?

 

[Ambient]

The mall down the road from me needs these devices! Maybe I can make one for fun and hide it in a flower pot before the mall rats arrive. The problem is these kids hang out near the exits and entrances to the theater. They are pretty stupid and block foot traffic flow, and are generally pretty annoying. It would be pretty fun to screw with them lol.

 

[Pommie]

The mall down the road from me needs these devices! Maybe I can make one for fun and hide it in a flower pot before the mall rats arrive. The problem is these kids hang out near the exits and entrances to the theater. They are pretty stupid and block foot traffic flow, and are generally pretty annoying. It would be pretty fun to screw with them lol.

It would be much better to give them something to do. The fact that the only thing they have to do is hang out in malls is really sad. Get onto your local councilors and get some facilities for these poor kids.

Mike.

 

[UTMonkey]

I Dont know how true it is but I heard from a friend who has a friend (of a friend) who is a teacher.

The kids use it in her school as a ring tone to alert them when they have a message in class.

Touche!

Mark

 

[eblc1388]

It must be a funny scene when some kid's mobile rings and everybody except the teacher noticed.

He/she just carry on as if nothing has happened.

That's a very creative use of the idea by kids.

 

[Nigel Goodwin]

It must be a funny scene when some kid's mobile rings and everybody except the teacher noticed.

He/she just carry on as if nothing has happened.

That's a very creative use of the idea by kids.

Depends if it's true or not though?, I would expect most phones not to work at that high a frequency?.

But a nice urban myth anyway

My younger brother and his friend Paul learnt the deaf/dumb sign language alphabet, so they could talk in class without the teacher noticing!

 

[Thunderchild]

hm difficult one no they don't solve the problem perhaps they will be a temp solution to a bad situation with police quality the way it is I'm not surprised other means of protection are being used but no they are not really fair and if used should only be used when strictly neccesary.

 

[Ambient]

I Dont know how true it is but I heard from a friend who has a friend (of a friend) who is a teacher.

The kids use it in her school as a ring tone to alert them when they have a message in class.

Touche!

Mark

That was mentioned on an episode of Law and Order that I saw a few months back lol. Cell phone speakers should be able to handle high frequencies, they are pretty small.

 

[Nigel Goodwin]

That was mentioned on an episode of Law and Order that I saw a few months back lol. Cell phone speakers should be able to handle high frequencies, they are pretty small.

I was thinking more of the filtering used, rather than the speaker - it's likely to be class D, so heavily filtered to reject the carrier.

 

[Ambient]

Ah I see. I didn't think the speaker would be filtered. I thought that since the signal came right from whatever D/A they use it would have a software filter. So I thought that high tones would not need to be filtered using an analog filter.

 

[peter5355]

Take an astable 555 timer tuned for 18kHz and connect it to a piezo tweeter.

I don't really agree with the use of child repellers because they'll cause problems for people with good hearing and for dogs and cats. I also think that children should have the right to be on the street.

Also there's nothing stopping them getting ear plugs or a ghetto blaster that pumps out a loud enough bass line to cancel out the near ultrasonic tone.

We have problem with birds would this repeller would that solve problem with them or is there hearing different I heard farmers are using them for rats and mice

 

[Thunderchild]

What about people who have hearing aids?

Could it generate subharmonics in them causing them to emit a loud low frequency noise?

no my dads gf uses hearing aids and she can't hear a high pitched sound being made outside one of our supermarkets I always assumed it was to keep dogs out but perhaps its for kids not that it makes any difference and its on 24/24, My dad can hear it a bit but for me and his gfs daughter (24 and 21) its a little bit annoying, well it is to me she said she can def hear it

 

[Thunderchild]

We have problem with birds would this repeller would that solve problem with them or is there hearing different I heard farmers are using them for rats and mice

high frequenzy has been used for years against insects and moles I suppose any animal is suceptable to certain frequenzies

 

[Hero999]

We have problem with birds would this repeller would that solve problem with them or is there hearing different I heard farmers are using them for rats and mice

Unfortunately birds have poor hearing at high frequencies, most can only detect sound up to 3kHz.

I don't know if this applies to all brids but I've heard that pidgins have excellant hearing at very low frequencies and can detect sounds well under 1Hz, which we can't hear, so an infrasonic repellant might be effective.

 

[peter5355]

Unfortunately birds have poor hearing at high frequencies, most can only detect sound up to 3kHz.

I don't know if this applies to all brids but I've heard that pidgins have excellant hearing at very low frequencies and can detect sounds well under 1Hz, which we can't hear, so an infrasonic repellant might be effective.

Thank you for your reply it is crows on the roof at 4.00 and 5.00 in the morning pecking it is like a drum it is driving me mad.

What is an infrasonic repellent?

and where would I get an circuit diagram for it?

 

[Hero999]

Infrasound is at the other end of the spectrum (below 16Hz) and is harder to create than ultrasound because you need huge sub woofer speakers which aren't cheap and you need to avoid creating audiable harmonics.

I don't have a circuit, a low frequency signal generator working at 10Hz connected to an audio amplifier with a large sub woofer on the output would generate some infrasound.

Even then, it might not be effective. I'd do some reasearch first as there's no point in going to all this trouble for something that might not work.