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Forum Index : Off topic archive. : Infrasound from wind farms
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| domwild Guru  Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Hi, Mentioned it before but it was an off-topic comment as usual and therefore did not get a bite. There has been a claim in the newspapers, that the low-Hz noise from the wind farms is causing health problems in residents. I believe this noise is in the inaudible range of 20-30 Hz and is called infrasound. It is in the wavelength the elephants communicate with. What I know is that this noise even has military applications. Scientists who worked with it found that it can rupture blood vessels, which apparently start to resonate. I can't remember if there even was a death. It is the sound, which leads credence to the biblical story of the "trumpets of Jericho", where the city walls fell. There is also the rumour infrasound has been used in Ireland to excite demonstrators, so that they become agitated to the point of violence allowing the military to intervene?? If there is truth in the rumour of health problems near wind farms, it would be most unfortunate and come in addition to the complaints of visual pollution. Let's hope it is only a rumour. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Dom I haven't heard any negative reports on low frequency sound only birds having in flight collisions with the blades. With all the sub woofers that some young blokes put in their cars they are subjected to much more noise pollution than wind farm LF noise. However if you see how brain dead some of them are it may raise the question of whether that is socially transmitted, genetically transmitted or brain damage by LF exposure in their boom boxes. All the best Bob Foolin Around |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Dom, If you dig deep enough in any situation there will always be negatives. Do you own a mobile phone ??? as apparently they kill you to or at least fry your brain according to some research, but we all still have them along with the visual pollution that many claim they give. ( i might add those who protest the visual impact normally have a phone in their pocket while protesting ) As Bob indicated the new generation DOOF..DOOF music is about the same as beating your head against a brick wall but that cool with the next gen. Its really a matter of which evil you choose in life to live with or isolate your self from. Todays standards of life has really got you by the goolies one way or the other. Pete. Sometimes it just works |
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| domwild Guru Joined: 16/12/2005 Location: AustraliaPosts: 873 |
The chaps with 120 decibel sound equipment in their cars wreck their hearing and qualify for the Darwin award as once their hearing is gone, they may not hear an approaching car and get killed - survival of the fittest! There is a web site which issues Darwin awards, like the one to the chap who used a 22 calibre bullet in place of a blown fuse and killed himself that way. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Dom My grandfather used to say that fools are self eliminating, but now with the cotton wool approach to work place health and safety and other protective methods in cars in the general life exposure to danger we are breeding a race of fools due to their non removal from the gene pool. I think that's how they breed politicians. All the best Bob Foolin Around |
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SSW_squall Senior Member  Joined: 20/03/2010 Location: AustraliaPosts: 111 |
Dom, I read that story about the .22 calibur bullet in the car fues holder, and i read it shot one of his nads off!! I reckon that is helarious 
Seriously i can say from presonal experience there may be some thing to the Low Frequency anxiousness: For the last year we have been developing a new amplified subwoofer the VOLCANIX and TEKTONIX (it's high quality low distortion bass NOT doof-doof), with home grown electronics that i've designed, check it out: Volcanix and Tektonix I anycase we were testing it out in the home theater listening room that has a projector and screen and watched a scene from a movie "the haunting" on a DTS demo disc. The movie was pretty scary (suspense - someone about to get attacked or something), the room was dark, the sound track had really low frequency rumbles and we had it cranked up LOUD!! (120dB) So loud in fact the sub was shaking it's self along the floor (which is one reason it will come supplied with attractive teardrop damping rubber feet) I can honestly say i was bloody scared, had goose bumps and felt like running away, even though i knew logically i was just sitting in a room watching a movie! I reckon it was the low frequency rumbles that really capped it off. I'd say it would have to be bloody loud to give this kind of result. Any less could well be annoying but probably not scary... Just my experience AB Einstein: Everything should be made as simple as possible, but not one bit simpler |
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| grub Senior Member Joined: 27/11/2007 Location: AustraliaPosts: 169 |
VK4AYQ said; "I think that's how they breed politicians." Reminds me of a joke I heard. A pretty young thing nerously enters the doctor's office and sat squirming on the chair. "How can I help you?" asked the doctor. The pretty young thing then leans forward and in a whispering voice asked the doctor, "Is is possible to get pregnant from anal sex?" "Certainly my dear", boomed the doctor. "How do you think politicans and lawyers are conceived?". As regards to the Doof Doof speakers in cars, I can never get over it how, when they drive past with their speakers going, the noise hurts my ears but it actually did not sound all that loud. They must be stone deaf in the cars and hear the music by viabrations alone. |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Grub Thanks for that information it explains a lot of things I have wondered about for years but was to stupid to see the reason for them. Hi SSW Sounds like you are going down the way I went in my young days. I used to build amps and speakers to order and set up sound rooms for people with plenty of money, We made a system using a Revox tape recorder eight track for surround sound with woofers for subs 18 inch Jensen theater speakers running on 1000watt valve amps, using 813 transmitter tubes running on ultra linear transformers. I haven't got the tapes anymore but I bet you would have liked to hear them. We also had a transducer floor shaker. The new surround sound on a good system is OK but dosent have the presence of a valve amp. Ah the good old days. All the best Bob Foolin Around |
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| SSW_squall Senior Member Joined: 20/03/2010 Location: AustraliaPosts: 111 |
Hi Bob, that stuff sound great, i can't say i've heard of surround sound on 8 tracktape, Prior to Dolby prologic there was quadraphonic surround sound on LP. I agree the *right* vacuum tube gear can be cleaner, quiter and more listenable that average. I've designed a fair bit of original equipment using vacuum tubes. My thesis project at university was 4ch microphone preamplifer, with calibrated magic eye level meters, Jensen input transformers and a super quiet 6BR7 triode input stage. The balanced cathode follower output stage was DC coupled with DC servo that kept the output at 0v but acted as a current source at any high frequency than 2Hz. 
I've also designed a push-pull 2A3 amplifier, with current source loaded gain stages By add the right transistor support cirucitry with vacuum tubes the performance that can be achived is FAR SUPERIOR. Replacing a humble plate resistor, with a simple current source load for a 12AX7 tube gain stage say, will slash the distortion, allow better load driving, higher idle current and lower B+ voltage... I some ways what i'm doing for a job is nothing new, because loudspeakers are fundementally mechanical devices they can't be improve in the kind of spectacular way that computers have in the last 2 decades, for example. Having said that the suspension on the average car today, would be regarded as better of that of the average car 20 years ago. In the same way loudspeakers have improved significantly over time. Some of the product we come up with in the last couple of years really have improved the state of play when it comes to home theater. Desiging the Epicentrix centre channel was one of those products as there very few comparable products around even now. In cinema or home theater the center channel is the most important louspeaker because it carries the dialog. Dialog intelligibilty is absolutely the most important consideration. When non concertric loudspeaker drivers operate at the crossover frequency, because of the interference pattern, there will be off-axis notches by definition. Hence the midrange and tweeter are placed vertically, delivering more consistant dispersion in the horizontal plane (where our ears are 4 time better at localizing sounds) And the drivers are placed as close together vertically to broaden the vertical lobe and reduce the notches above and below axis. Constant directivity, makes the most enormous difference to how intelligibly dialogue or (any audio for that matter) can be... I'll stop blabbing now... AB Einstein: Everything should be made as simple as possible, but not one bit simpler |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi SSW Sounds like you really got into the action as well, those where interesting times I got involved in the early sixties when at college doing electronics and started doing public address systems with multi channel facilities using 6cm5 valves in pairs and quads then to get the extra power we went to transmitter valves, the quad system we used was our own as there wasn't any other available at the time, we live recorded with the Revox 8 track music and sound effects so it was a labor of love and frustration at times. We used multi channel amps to drive each set of speakers as we got to much phase shift distortion from a crossover network so that meant 16 amps for each setup, you can see why it never went ahead.. The four range frequency split system was desigened for us by a friend who worked at the CSIRO and the mixer valves where a premium grade version of a 12au7 used in the old valve type computer once they sagged a bit on output they tossed them so we had a good supply of nicely run in valves gold plated pins and all may have been a bit down on power but matched up in sets they where great very low noise. All the surround sound these days is interesting but when listened to critically is a mass of phase distorted muffled noise to a large degree, some top end systems I have heard in the States get it better but at a cost few can afford Im afraid, We where building 4 and six speaker columns for PA work and the speakers morphed from their. All very interesting but Im afraid a bit beyond me now, I like your creation pictured as that has wires and things you can see not like the new stuff now if it gives trouble you throw it away and get a new one made by slave labour in Asia. It leaves me cold now as even when I hear an average system, it is noise of varying quality, most people think that loud noise is a substitute for sound quality, and they don't even know how to place speakers for best sound. It's good to see someone is still working on quality not quantity, unfortunately it is to expensive for the masses or even the would be enthusiasts but at least the cause isnt dead. Back to playing with windmills and praying for some wind to work them. All the best Bob Foolin Around |
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