Teenager repellant....

[Dr Mordrid]

http://www.breitbart.com/news/2006/02/15/060215133756.3rq2yx5p.html

Where do I get one?

Dr. Mordrid

[Gurm]

1. I guarantee you I can hear that pitch. To say that most people lose their high-pitched hearing in their 20's is just rubbish. I can hear a computer monitor fire up from 2 rooms away. I can hear the 60-cycle hum of a TV in the BACK of a Wal-mart when I walk in the door, even if it's shielded.

1a. To add insult to injury, any noise in that range will make every tinnitus sufferer in the area start SCREAMING. Way to go shopkeepers!

2. If you want a "sonic teenager repellant", crank up some Frank Sinatra - or any showtunes, really. Less harmful, cheaper, and I guarantee the results 100%.

[Mehen]

But then you are forced to listen to showtunes...



(I guess you are right then - it would work on me - and I'm in that targeted age bracket )

[cjolley]

Doc, you can answer your own request.

http://forums.murc.ws/showthread.php?t=55753

[KvHagedorn]

I read where a McDonalds in some urban area did this by playing classical music. Nothing like Mozart to weed out the scum and keep the good folks.

[schmosef]

A girl I used to date who was studying interior design said that McD's colour scheme was used as a case study in her class.

Supposedly it's designed to feel warm and welcoming when you first walk in but also make you want to leave after 20+ minutes. The bright colours feel welcoming at first but become disorienting over time.

[TnT]

Welcome! Here's your pile of crap food. Now leave.

I think showtunes is a great, harmless way to deter people.

[Brian Ellis]

1. I guarantee you I can hear that pitch. To say that most people lose their high-pitched hearing in their 20's is just rubbish. I can hear a computer monitor fire up from 2 rooms away. I can hear the 60-cycle hum of a TV in the BACK of a Wal-mart when I walk in the door, even if it's shielded.

Wrong again, as any audiologist will tell you. The work done by Fletcher and Munsen in the 1920s supports it. It also depends on the intensity. The threshold of hearing at 18 kHz averages at -40 dB for adolescents and at -85 dB at the age of 30, wrt to 1,000 Hz. This has nothing whatsoever to do with the 60 Hz hum, which is nearly at the opposite end of the audible spectrum. In any case, the 60 Hz (50 Hz in most parts of the world) is much more likely to come from the magnetostriction of the ballast coils of fluorescent lighting, the transformers of many electrical appliances, than from a TV. If, OTH, you mean the 31.468 kHz magnetostrictive frequency emitted by the line/EHT transformer, then you must have had a pipistrelle as an ancestor. AFAIK, no youngster has ever been able to detect more than about 23 kHz.

I had an audiology test when I was about 40 and my top frequency detectable was 14 kHz, down from 19 kHz, when I was a student of ~19 years. I hate to think what it is now, probably ~10 kHz (call me cloth-ears!). The F&M curves, representing an average human hearing, stop at 15 kHz, at the point where the threshold of hearing coincides with the threshold of pain.

[az]

One CAN hear TVs, but one does not hear the 50/60 Hz sound they may emit. I forgot what it was, but a TV technician once told me, I think it was the line transformer or something, and we probably hear a harmonic of its real sound. Poor cats

BTW, KvH, the stereotype that "bad" people don't like classical music and/or that hearing classical music is a sign of something good is just getting old.

[KvHagedorn]

Sorry, but it's true. If you are a thug you are repelled by classical music.

[VJ]

Wrong again, as any audiologist will tell you. The work done by Fletcher and Munsen in the 1920s supports it. It also depends on the intensity. The threshold of hearing at 18 kHz averages at -40 dB for adolescents and at -85 dB at the age of 30, wrt to 1,000 Hz.

Well, I had an audiology test (part of the medical test for pilots), and it turns out that I'm part of the small minority that can hear outside the normal range. The audiologist didn't give the exact values, but said he was impressed (rarely seen this).

While it sounds (no pun intended) cool at first, it yields some problems. Most devices are tailored toward the average, with the result that some electronics (esp. crt tubes and cd/dvd players) emit very high pitched sounds: the majority won't hear it. But I can...
Long exposure to these noises gives me a migraine-like feeling. (I've sent back a radio, a cd player, a pc monitor and minimized use on one tv for this)


Jörg

[dZeus]

Do you hear 100 Hz PAL TVs? With a 50 Hz one I can hear a very loud high-pitch 'squeek', but with a 100 Hz I don't hear anything.

[Marshmallowman]

100Hz certainly is not a "high pitched" by any strech of the imagination.

100Hz crt tv are expensive hence have better high voltage tensformes(less noise and hum).

and if you are taking about 100Hz lcd's ..etc well they have no noise caus ethey have no componets likley to cause noise.

With crappy 50hz tv's you are probably hearing the a harmonic hum from the high voltage gear, interestingly enough I found cleaning some older TV's ,by removing dust from the internals can reduce such noises.

I used to be one of those with very good high frequency hearing...I certainly notice the squeals i *don't* hear any more

[az]

There are some LCDs that have a noticeable hum or squeal: harmonics from their backlight inverter.

[VJ]

100Hz crt tv are expensive hence have better high voltage tensformes(less noise and hum).

The 100 Hz my parents have (a Philips top model, it even has PALplus) makes a high pitched sound.
The tone is dependant on the image displayed: the tone slightly louder (I think, it is more prominently present, but I'm not sure if it is due to volume or to a differnt pitch) when bright images are shown, compared to when dark images are shown. Without a source, the TV shows a blue screen, and then it is at its most quiet (same level as when it displays teletext/ceefax).


Jörg