Monday, April 16, 2012

Know the enemy: The LRAD sound cannon

Weapons manufacturers have discovered a fresh customer in the DHS and "law enforcement" agencies of our country. Especially against our 1st Amendment right to protest.

Chicago Police Ready for NATO Summit Protesters With 'Sound Cannon'

"Chicago police have been increasing their supply of riot-control equipment, including the controversial long-range acoustic device (LRAD), also known as a 'sound cannon,' in the lead-up to the NATO summit protests the weekend of May 19, the Guardian reports today.

Confirming that they would have a sound cannon at the protest, Chicago police told the Guardian it would serve 'as a means to ensure a consistent message is delivered to large crowds that can be heard over ambient noise.'  But the LRAD can also emit a 'deterrent tone,' which some have said is capable of causing permanent hearing damage.

The Guardian reports that the CPD has spent $1m on the riot gear for both officers and horses."

Chicago Police Sound Cannon: LRAD 'Sonic Weapon' Purchased Ahead Of NATO Protests (VIDEO)

Chicago police roll out and demonstrate two $20,000.00 each LRAD sound cannons. 

UK rolls out LRAD sonic gun for London Olympics

"The UK Ministry of Defence has confirmed a device that can be used as a sonic weapon will be deployed at the London Olympics. The US invention is capable of projecting an ear-splitting sound beam of 150 decibels and was used in Iraq.

At full power the device can produce a piercing 150-decibel beam of sound, just 10 decibels away from the force needed to rupture an eardrum."


The Long Range Acoustical Device, or sound cannon, produces a unified, phase-aligned, high-amplitude barrage fully and execrably capable of permanently damaging or eliminating hearing.

It pays to understand a bit about it, from a layman's standpoint.

-The human ear is most sensitive in the range from 1KHz to 3KHz, or 1000 cycles per second+ of repetitive sound frequencies. Repetition of a waveform  produces its frequency, or pitch, being low (bass) or high (treble). Woofers and tweeters. It is not a mistake that the cry of a baby or child sits directly upon this most sensitive frequency range.

-Sound in open air decays in amplitude, relative to frequency. Bass carries and propagates wildly, and higher frequencies vanish in proportion to distance. The further away from the source, the less higher frequencies will reach you.

-Sound also disperses in proportion to frequency. Higher frequencies tend to leave a transducer / loudspeaker in a beam which increasingly narrows relative to frequency. Bass is nearly, but not entirely, omnidirectional. Wendy Carlos has presented an interesting text on bass directionality and the need for two subwoofers in a surround-sound setup, aka: 7.2, with the .2 being two woofers.

  This means that if you are not directly in front of the acoustic device, the higher frequencies will miss you nearly entirely. The beaming characteristic is easily discerned in the following video; watch as it sweeps across the camera person's position. The highest frequencies are only most unpleasantly present when the weapon is aimed directly at you. So of course, they put it on a rotating mount...

Higher frequencies go in and out at 0:45:

The video in the above "Chicago police sound cannon" link states that the device emits a 30 degree cone...that is likely the average due to dispersion characteristics versus increasing frequency. Much of this is moot as the device can produce middle frequencies in our sensitive range at enough amplitude and duration to permanently destroy hearing. We also do not hear with our ears alone. Our cartilage and soft tissues and the water in our bodies also all resonate with sound. Bone conducts sound extremely well. It is unknown how much we would perceive through our skull and tissue if our ears were entirely protected.

Suffice to say, if you hear odd tones adding to the LRAD's, your ears are distorting and are adding subtle distortion. This means you are in trouble, despite any and all protection you proffer.

This picture from the Toronto Sun is not entirely accurate due to some minor disperson but nonetheless:

LRAD Toronto Star

The best generally-available earplugs reduce sound around 25dB or so and again are frequency-dependent (high frequencies are the most reduced, but reduction falls off possibly below the dB reduction stated at lower and lower frequencies). If the attack is at something on the order of 140dB or greater, you can still suffer frequency-specific permanent hearing loss. Gun-range ear protection, combined with good earplugs, may give you a chance against hearing damage. Shooters combine plugs with ear muffs. Consumer-level noise-cancelling Bose headphones will likely not work at the 150dB levels output by this monstrosity. Noise-cancelling ear muffs used by the aviation industry may work...

Let history show that we the citizens of this era rebuke and renounce the fascist, sadistic monsters controlling this world and those who willingly assist.