For all those who have not seen the 1996 Movie “Mars Attacks”, let me inform you that it is well-established science fiction fact, whereby Country Music that involves yodeling, especially a song called “Indian Love Call” can provide lethal force in the case of alien invasions. For reasons which director Tim Burton chose not to elaborate on, this music makes their head pop. Mine just hurts a little.
But what about the real world I asked myself a few days back. We have all heard about sonic weapons being developed and perhaps already being used, but what is the science and state of technology of using sound in warfare?
I remember very well reading a piece on the news that was aired in 2005 but apparently raised few questions in main-stream media. In November that year a luxury cruise ship called the “Seabourn Spirit” was reported to have been attacked by two dinghies full of evil-doing up-to-no-good pirates, 115km off the coast of Somalia. One thing that came to mind immediately was of course that “seabourn” is not an English word, versus perhaps “airborne.’’ The correct word would be simply ‘’floating,’’ but I am sure that the marketing folks at “Seabourn Cruises” were rightly hesitant about a “Floating Cruises” brand evoking anything beyond merely the expected.
Either way the misnomer vessel was attacked by a group of Somalian pirates who were reasonably well-armed with rocket propelled grenades and machine guns. At least two such grenades hit the ships side wall; one bounced off and the other lodged itself into the wall, injuring none of the 115 passengers, but the master at arms was hit by shrapnel. At that point in my life I learnt that cruise ships had masters at arms. More interestingly, that man Som Bahadur Gurung, highly trained former Nepali Gurka was not exactly defenseless: He was operating what is called a LRAD which is short for Long Range Acoustic Device. I also learnt that cruise ships have those.
Some media reported that sound was being used as a weapon and that cruise ships had those weapons and apparently they worked. Other vessels that are reported to be equipped with such weapons was the MV Biscaglia which had been attacked and entered by pirates so quickly that security staff had no time to deploy their contraption. In 2011 however, the Spirit of Adventure successfully deployed an LRAP during a massive pirate attack in the Indian Ocean.
The Japanese whaling fleet started using them against activists like Sea Shepard Society including one rather harsh sounding incident where it was pointed at a helicopter carrying a camera crew. Sea Shepard on the other hand boast to also possess one, but only uses it to play Wagner’s Valkyries. Let’s hope they don’t escalate to country yodeling, one day.
Now not only cruise ships use LRAD`s. At least 18 countries have them and several US law enforcement agencies own and use them to suppress riots and disperse crowds. Well, if it works on pirates, it should convince people in Ferguson that police brutality is only a problem if you have a problem with police brutality.
Of course for a loudspeaker designer and manufacturer like me, my primary interest is not primarily politics but acoustics and of course the idea to use sound as a weapon strikes me as interesting.
Sound can in fact inflict severe pain, disorientation, damage to the eardrum, a drop in body temperature, and blurred vision by means of making your eye drums vibrate and dificulty breathing. Certainly. Not. Fun. An instinctive reaction is to cover our ears and run away, which may well be a problem as the sound of an LRAD is reportedly impossible to locate as it possesses no stereo-imaging cues and someone whose intention is actually to disperse might well run towards the source of the sound instead and be mistaken as an attacker.
A top Notch LRADS like the 2000X series has an output power of 165 dB at 1m. That is incredibly loud. Thanks to the good people at makeitlouder.com this is about as loud as being on the inside of a large jet engine. It is also as loud as the Large European Acoustic Facility designed to simulate the acoustic environment present in the direct vicinity of a very large rocket during launch.
One meter is however incredibly close and plugging your ears will provide a 20dB drop. bringing the sound level down to the loudest rock concert ever. Wearing good earmuffs provides another 10dB, so if you are a pirate, by all means get a pair of those.
The company states the range of its flagship device at 3.5km with 6dB over a noise floor of 88dB. This means that there is a gradual drop in loudness of about 20 dB per km showing just how incredibly directive these devices are.
But how is this accomplished? Inside an LRAD there are many very small piezo electric transducers that produce miniscule movements using the deformation of crystals under an electric field. Each movement is rather small, but together they do put out a lot of sound. Together they form an array, which by means of acoustic lobing already can be very directional. The trick in making them directional is to stagger them to wards the outside of the bowle to were 180 degree phase shifts are produced that cancel an sound outside the beam.
The effect is quite surprising: The directionality is such that sound that is outright painful in its loudness is almost inaudible just a little bit outside the beam.
But what happens in reality? Most of all LRADs in use by law enforcement and cruise ships today are made by a San Diego company called LRAD Corporation. The company suggests use in for steps ranging from giving people instructions to what they call escalation of force. Here is an example of what steps 1 through 3 looked like in the dispersion of Occupy Wallstreet in NY.
It does not appear that any of the people experienced any sort of physical harm, but they do appear to be angry. So what is the science of things?
The American Civil Liberties Union and other similar organizations are concerned about the use of this device in the hands of the police and Terry Schappert with Digital Justice tries to see both sides of the divide.
In my personal opinion, I do not think that sonic weapons like the LRAD are very effective, at least it seems like those blokes with the Pittsburgh PD at the G20 summit probably wished this thing would actually work at all.
In all honesty, and despite my personal bias towards free speech, and the right to peaceful protest, I don’t see LRADS being any more than annoyingly loud megaphones. I do see their purpose in emergency response, riot management and wildlife control to keep foul away from airports. I also see their potential for being abused by infringing with peoples right to assemble and protest. If their primary purpose would be to actually hurt people, focused microwaves that induce painful heat in people’s bodies are much better at that, can be focused more narrowly and actually can be used as a weapon that is not easily defended against with ear-muffs.
The true story around that November day when the “Seabourn Spirit” made history is probably that after two rounds fired, the pirates ran out of ammunition and found the sound from the LRADS a little too annoying to want to stick around much longer. An that might well be what sonic weapons are: Very hard to be around, and certainly loud enough to interfere with free speech at their owners discression, but they are not suitable to seriously invoke bodily harm in people. And for those of you who do consider pursuing a career as pirates, there seems to be an emerging market for earmuffs that are right for you.
Arved Deecke is founder of the Danish / Mexican Loudspeaker company KVART & BØLGE that makes audiophile quarter wave loudspeakers and sound systems at a price anyone can afford. In his free time he blogs about all things related to sound, music and audio.
