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A relatively virgin area of the revenge world is the use of acoustic ultrasonic energy to disorient and disrupt victims. In plain English, this means using sound that is above the frequencies of normal hearing to fuck with people. Ultrasonic sound normally starts at about 15,000 or 16,000 cycles and works its way upward.

Although devices capable of creating such sound levels have been available to the scientific world for years, the cost of the transducers (that is, the "speakers") has been high enough to keep these devices out of the hands of amateur social experimenters. However, the advent of the piezoelectric tweeter - a miniature, high-frequency transducer for use in higher-end stereo systems, has brought the use of such devices within the realm of serious pranksters. Ultrasonic sound is, by definition, inaudible. However, every individual will have a varying response to these sounds. Because of this, the following units will produce significantly different results on different targets. It is safe to say that in almost all cases, some response will be noted.

The two units detailed here vary abruptly in price and in their pain-producing threshold. Both will work on people and animals. Dogs in particular can't stand these units. A number of successful experiments have been carried out by persons known to me to "train" a neighbor's barking dog to have a bit more understanding of the concept of privacy.

The first device is a single-transducer ultrasonic generator capable of directional transmission of time-variant ultrasonic energy. The "noise" produced by this device will be at the upper limit or above most people's hearing (it has been my experience that people with very fine upper-hearing borders are able to notice the sound of the unit when asked to do so). The frequency is high enough, however, that most people would not realize any sound was present without a reason to listen for it.

In order to test the validity of this statement, it is only necessary to point this unit from a distance of five or ten feet at a crowd of people who have been prewarned and notice their reactions. In my experience, women tend to be bothered more than men, but almost everyone reacts in some manner to the unpleasant intrusion of ultrasonic energy.

How do people react? They will feel an unwanted sense of pressure and irritation, even though it is generally impossible to pinpoint the reason or direction of the unpleasant energy, as high frequency and ultrasonic sound waves tend to appear nondirectional to most humans.

To reiterate, this small unit emits a high-pitched noise that is almost impossible to hear but which will invariably produce a feeling of unpleasantness and physical discomfort in the subject after some exposure.

The unit is powered by an internal nine-volt battery that gives it enough strength to last for several hours. It can also be turned on indefinitely by the addition of a nine-volt battery charger/power supply available from any electronic-supply store.

The unit is small enough to hide inside a hollowed-out book, radio, lamp, computer, or any other object that can be placed in the immediate vicinity of the target.

One particularly interesting application the author observed was when the unit was taped above a false ceiling (the kind found in many offices) and aimed down on the intended victim.

After a short time, the person (in this case, a rather obnoxious employer) became more irritable than usual, broke pencils, snapped at people, and eventually went home early with what he described as a splitting headache, thus removing a source of unpleasant behavior without it causing any permanent damage.

The unit can be purchased on a set frequency (which happens to be one most dogs can't stand), making it a legitimate warding-off device for joggers, hikers, bicyclists, and others who wish to leave the .44 magnum in the drawer when they are exercising or who simply want to convince the neighbor's dog to stop barking.

The unit can also be purchased with a variable control on the generator that allows fine tuning in order to select the frequency that appears to be particularly offensive to any target.

This device can be employed in an intermittent fashion, bringing about what I call the "earthquake effect." The target will often look at his tormentors or other people in the vicinity and ask, "Did you feel that? What was that? Did you hear that? Wow!" or other exclamations of confused agony. The incomprehensibility of ultrasonic sound is one of its strongest advantages. There seems to be nothing there to complain about, but there is ...

I personally recommend this unit. For the outlay of only a few bucks, it can provide the semiserious nasty person with a variety of pleasant experiments in the fine art of subtle revengemanship.

This device, as well as the following one, can be built from simple plans (not advised) or purchased for about fifty dollars in kit form or seventy-five dollars in a completed version from Information Unlimited (see the Suppliers chapter at the end of the book for address).

Imagine the effect if one were to take the ultrasonic generator one or possibly two steps further ...

A number of government researchers have done just that, producing devices designed for riot control and crowd disruption. Think of them as sonic versions of CS tear gas. These devices are so effective that they are being considered by various state and government agencies for regulation and/or licensing, in much the same fashion as firearms. I am not implying that the BPF4 is in any way, shape, or manner capable of inflicting the same damage as a firearm. The unit is simply effective enough that the government thinks its use should be regulated.

The BPF4 can be purchased in various stages, ranging in price from fifteen dollars for the plans only to three-hundred dollars for a complete unit. Granted, this is a lot of money to spend on something that has little or no practical application for most people.

The key here is the term most people. How serious of a prankster are you? If the device might save a person's life that is, someone you might otherwise be tempted to push off a balcony or shoot. I can only consider it a fair investment for the money. If you are bothered by a loud, barking dog nearby or a neighbor or spouse who invokes the same reaction as the obnoxious dog, and you have no wish to poison either, you might consider this far less permanent method of behavior modification.

The BPF4 is built inside a 7x7x6-inch enclosure and requires the application of VDC at three amps via rechargeable batteries or by the convenient presence of a twelve-volt video camcorder-type battery. The latter will provide approximately one hour of the most irritating operation imaginable. This device is powerful enough to be used for property protection. By wiring it to a burglar alarm or other intruder-sensing device, the BPF4 can provide an immediate impetus to the unwanted trespasser.

Description of image: Revengist's boombox. This device has approximately the same effect as a 100-watt ghetto blaster when it's going ballistic. The difference Is that you can't hear this one. It will clear a path through the dregs of humanity or the animal kingdom, whichever Is necessary.

The BPF4 produces a very high acoustic-pressure level composed of both sonic and ultrasonic energy waves and can be adjusted in frequency and sweep time by the use of external controls. The controls give the user an almost infinite number of choices, at least one of which is guaranteed to drive anyone crazy...

As the photo shows, this device consists of an array of piezoelectric tweeters (eight in this case) driven by a powerful ultrasonic generator. This system produces noise over a fairly wide frequency band. There is also a switch for an immediate 10x power increase, allowing the operator to adjust the unit for maximum output and most irritating sweep rate and then kick it into overdrive, so to speak, jamming the output into the ultrasonic range for immediate results.

The output of this unit is almost, as they say in the ads, indescribable. Imagine yourself lying in front of four-foot high stereo speakers with a sixtv-watt per channel amp cranked up well past the pain threshold, playing an album of someone sliding his fingernails down a black board.

Like the image? That's about as close as I can get to actually translating the effects of the BPF4 into print.

At one point during the testing of the BPF4, a friend of mine came in the front door just as I was about to apply the power to the unit.

I applied said power. She looked at me, turned around, ran out, and slammed the door behind her. To make a long story short, I ate dinner alone.

Granted this was not the original idea of the proper use of this unit, but it does serve to illustrate a point. As someone else suggested, this unit could be called the "adult's boombox."

A good image of this application comes to mind. Once I lugged my BPF4 to the local beach on a warm, sunny day. Now, as with every beach in the civilized world, and one must assume even in Libya, our beaches tend to be jam-packed with normal, God-fearing, door-shutting, toilet-seat-putting-down, saying-"excuse me"-when-they-leave-the-table people. Yet there's always one dumb son-of-a-bitch who has convinced himself through heavy doses of illicit drugs that we all share his musical tastes. Unfortunately, these tastes always tend to run towards those rare copies of Whipping Madonna, The Rap Version.

This SOB invariably finds the best spot on the entire beach, which for some reason is always located within ten feet of where I've staked my property lines. Perhaps this goes back to my childhood when an alien gave me the strange power to attract the only assholes in a theater. This always includes two people who had already seen the movie and were dying to tell their friend every move right before it happened. Talk about killing Walt Disney…

But I digress. The BPF4 can easily be inserted into an acoustically transparent carrying case such as a beach, tennis, or gym bag, where it will attract little or no attention. This disguise is useful when some over-hormoned teenager who hasn't washed his hair in five days turns his boombox up to ten, as happened on this particular day. He was drinking tequila straight from the bottle, which he then casually tossed aside. He lasted about two minutes after I switched on the power.

The BPF4 is directional to a certain degree. However, you will notice there is some back splash, so you might want to wear earplugs or miniature headphones if you are going to use the device in close proximity.

If the unit is to be used for dog training, it is only necessary to employ the device immediately after the animal barks. After a short period of time, the little hairball will catch on and probably hesitate to even go outside, much less bark.

It is actually possible to hook up this device with a microphone so that it auto-reacts. When the dog barks, the device turns on for a few seconds and then turns itself off.

Although definitely an upper-end piece due to its price, the BPF4's possibilities are limited only by one's imagination. But for driving out errant roommates, creating schizophrenic behavior in the neighbor's vociferous, overtaxed dog, or putting a damper on obnoxiously loud beach parties, sports fans, or people who seem intent on making your life miserable for no earthly reason, it works.

While the use of ultrasonic generators could be considered an obnoxious move in itself, especially if employed by unscrupulous types to procure seats at concerts, stadiums, World Professional Wrestling, or other highbrow socialite events, it should be remembered that this device does not do any permanent damage and accomplishes one's immediate needs without digging out that black-belt-adorned karate gi that's been collecting dust in the closet all these years...

Not sold in any stores.