The LRAD or the long range acoustic device that has been developed by American Technology Corporation is capable of emitting a maximum of 151Db sound within 30 degrees of where the device is pointing. This device can be used as a combatant deterrent weapon or crowd-control device by emitting sounds that are painful to the ears.
The LRAD weighs about 210 kilograms and is capable of emitting sound within a 15 to 30 degree beam. The range of the LRAD is 300 to 500 meters and, at maximum volume, it can emit sound 50 times greater than the human threshold for pain so it can cause permanent damage.
Sound Propagation Principles used by LRAD
Sound waves spread out in all directions as they travel through a medium and lose strength proportional to the distance from the source. High-frequency sound waves, however, spread out less than low-frequency sound waves. Moreover, sound waves with longer wavelengths travel a lot farther than those with short wavelengths. Sound waves can also either cancel each other out or merge together into a sound wave with higher amplitude depending on whether they are out of phase or not.
LRAD applies all the abovementioned properties of sound to make the device work.
The Technology behind the LRAD
Instead of the usual diaphragm that normal speakers use to make sound, the long range acoustic device uses a set of piezoelectric transducers which are capable of converting electrical energy into sound. These piezoelectric transducers are permanently polarized, so any distortion of the shape of such transducers creates an electrical impulse and vice-versa. By using a power source to supply this electrical impulse, piezoelectric transducers can rapidly change their shape, therefore, creating sound waves in the process. The transducers are also arranged so that they are in phase with each other so that the resulting sounds they emit can combine to make the projected sounds louder.
The sound that the LRAD produces can be directed so there's less-than-normal dispersion. This results in a 20-dB drop in the volume of sound 15 degrees outside the beam. This directional sound propagation stems from the fact that the LRAD employs outer and inner transducers in creating sound waves that are not completely in phase with each other. This enables other sound waves to cancel out those that are in the outermost portion of the beam. The resulting wave front of the sound is also flatter than usual, preventing the sound from being dispersed as it propagates. Moreover, as the LRAD-produced sound waves interact with the air, they create additional frequencies within the wave and thus amplify the sound and pitch.
Advantages and Disadvantages of LRAD
The primary advantage in military and law enforcement circles is that the LRAD is a less than lethal solution that has the potential to prevent antagonists from continuing their unwanted activities, without endangering the friendly personnel.
The major disadvantages of the LRAD system are:
- The loud sounds the LRAD emits may cause permanent hearing damage to those within its range.
- The LRAD sound wave can be cancelled altogether through the use of common earplugs. The better the earplugs are at blocking sound waves, the less effective the LRAD is.
- Sounds emitted from the LRAD can be reflected back to the source by using a flat solid object.
junkyardnut
They are still doing this to me!!!
junkyardnut
The shitty vibrations and smells had stopped for past half hour, so far so good.. I am 99.9999% certain that it will return .. During the meanwhile, they are digesting or indigesting all my shitty comments I made this half hour.. ago.. I hope they will just go away !
for-eveeeeeeeeeeeeeeeeeeeer! good riddance ! My shitty neighbor can also move out after all it was their original idea all along not mine.. I am gonna stay put here… They can go ! I will be so happy to see them go with their evil !
junkyardnut
We must be living under the government that has a kind left arm while harassing people with right arm.. at same time.. LIberals? my ass!
junkyardnut
james you can think funny jokes until it happens to you.. you will go mad banana!
junkyardnut
I am also happy to know that I am not alone as I was always certain of that.. I hope more of us will come forward until the day comes when the authorities have to start owning up to this and get hella outta here!
junkyardnut
Darren, it is possible that you are being considered as a persona non grata so they harass you. I am not trying to poke fun at you because I have same thing happening to me as described by you here. Also, it is possible that it makes me smell things that is not there as if my brain is pinpointed precisely where my smell is.. and being fried… I don’t know.. It also feel like there is vibration deep underground. . I am currently assuming that someone is burrowing under my house and operating some kind of electricity generation there to make extra cash selling back to the local utility because I notice that my neighbor’s meter is somewhat different than mine.. It looks like they are not paying anything for their electricity because they got a big generator under my house..I suspect that the local utility had awarded my neighbor a long life contract to help supplement the power demand in my immediate neighborhood blocks where several neighbors have big arc welders that often trigger black outs by blowing up the local transformer so often. My neighbor is using my property without my knowledge , never mind my consent which he would never get any! I am currently employing counter measures to stop their operation temporarily. But they simply came back on , anyway.
junkyardnut
They are as plainly trying to drive you out of town for all they care… for whatever reasons that you can only dream out for yourselves.. At least, you still have basic rights to stick it out for yourself if you still like your own dig. so be it.. Just f**K them!
junkyardnut
james., LRAD is not audible.. it rattles your bones.
Robert
LRAD is most certainly audible, It can be used to broadcast many different kinds of sounds.
junkyardnut
yes audible is one of them but there is much more to LRADs than you suggest.. I don’t know whether you are attempting to mislead other readers into thinking that LRADs is strictly audible which it is not.. LRADs is used on terrorists in capitivity in Cuba to harass them .. Infrasonics can go through walls and your damn bones and skulls!
My neighbor with help of local police in Antioch , California is using this on me most definitely.. It is torture and torment !
Robert
One type is painfully loud and high pitched.
junkyardnut
I agree with you as similiar things is still happening to me, too. it can be the work of your neighbor? it is called harassment. Call a lawyer specializing in harassment, but will the lawyer lend any sympathetic ear?
junkyardnut
Funny, the vibration stopped so suddenly as I posted these above.. but hey I know that it is coming back anyway.. unless some fancy lawyer decide to come to my door and really knocks!! I will be very grateful !
mike victor
Instead of reflecting to the source, find a softer target. The reflected sound won’t be as strong. Reflect it at something vulnerable and less protected.
Give everyone a lightweight (foam-core based?) acoustic shield, about 24 inches square. Give it a good enamel coating and paint it with lovely thoughts about dangerous acoustic weapons. Aim the boards in the direction you wish to relay your views on using these dangerous devices on unprotected people.
Barb
LRAD broadcast abuse leaves the United States vulnerable to a new kind of attack on our personal privacy —jammerproof.
Devan Beiswenger
Is it possible for civilians to buy any type of LRAD and if so, how much would they be?
memenode
You can check LRAD Corporation’s “where to buy” page and ask them. It’s likely to be expensive though, even if they would sell to a civilian. There’s one LRAD for sale on eBay, assuming it’s not a scam since the seller has zero reputation votes, and it’s priced at $15000 BIN.
What would you use it for though?
April Storms
Same as the coppers use it for . Create a bloody nusiance back
James Hampton
Well for one idea you can annoy the s#$t out of people by aiming it at backed up highways and blasting show tunes, country western, xxx audio books, god awful 80s music, self help tapes, in a monotone voice the history of the most plain boring object you can think of, recorded ads for pills and ointments that help with a defective “tent pole”, annoying insurance ads, britney spears, justin beiber and so much more inappropriate/annoying material for several hours, which i think is f#%king hilarious.
Steve D. Ortega
Would Law enforcement be required by law to prevent others from using ultrasound on other people, to cause them to be psyhologly tourcherd and even to be dianosied as a syitafernicy. What, if any charges would brought against this person or others if apperhenned. Since there no laws to regulate ultrasound and acoustic devices. What of the victem?
junkyardnut
not ultrasound , to the opposite end called infrasonic low pitch below bass sounds mixed with other unknown wavelengths as piggyback to get through walls and stuff to your bones. you cannot hear much of it if nay.
Robert
LRAD is not designed for infrasonics. I know your going to argue with me, but it is designed for 1khz to 5khz, well within the normal hearing range of people. Is is not designed for sub kilohertz. (infrasound is 20hz and below).
I
“Contrary to some reports,” says the LRAD Corporation’s website,” LRAD does not generate the ultra low frequency tones that are needed to cause nausea and disorientation.” But it also notes that “LRAD broadcasts have been optimized to the 1 – 5 kHz range where human hearing is most sensitive.”
junkyardnut
Pure bullshit now go away!
Robert
Asbsolutely not. Feel free to ignore me but under no circumstances will i go away. Your refusal to believe facts is your own problem. I have looked in the specifications and they are not designed to emit infra-sound at all. You could easily verify this your self. But your flat out denial to look into it shows me you would prefer to complain about bogey men then understand what you are talking about. To produce infra-sound at high enough decibels requires a very different setup. Usually done with a rotary subwoofer.
On a side not. The brown note does not really exist.
junkyardnut
Robert, if you are right about that not being LRAD, you still fail to come with the right name or term .. If you know what it is so how come you never offer any name that I can use to do further research and get more pertinent with lawyers or cops if appropriate.. maybe you are a secret agent … you pig
Robert
What do you mean, “i fail to come up with a name or term”? You mean a name or term for your ficticious infr-sound weapon? Of course i don’t because its not out there. As i said they use audible sound at very high decibels.
Lrads main + is they are highly directional and if you are outside the beam you are unaffected.
AJ Ballard
LRAD was developed by General Dynamics, Bath Iron Works Advance Technology Division for the US Navy in 2002 in response to the USS Cole attack.
The correct term for this technology is Acoustic Hailing Device, which there are other manufactures such as Ultra-USSI who make the Hyperspike Acoustic Hailing Device and IML Corp who makes the Sound Commander.
junkyardnut
I don’t think LRAD is very new as they probably are being developed with latest advances in sonics and whatnots over the times.. It was probably why many people went mad and get committed in mental wards through no faults of their owns.. They were probably considered persona non gratas , anyway. So why not harass their brains out!
junkyardnut
The cruelest irony is that those Americans who are being harassed by fellow Americans have nowhere to go if they want to escape America…. Come think about that…