“Ghost Army” was the nickname given to a division of the U.S. Army, the Twenty-Third Special Troops, stationed in Europe during World War II. They consisted of artists deployed in the fabrication of camouflage and fake inflatable equipment, and sound and radio engineers using equipments pioneered at Bell Labs. The Ghost Army’s aims were to trick the enemy into reacting against the presence of a nonexistent phantom army using the sounds of troops, tanks, and landing craft, allowing the actual troops to maneuver elsewhere. In addition to the Ghost Army, Division 17 was working on a joint army-navy project based on “The Physiological and Psychological Effects on Men in Warfare,” research orchestrated by Bell Telephone Labs and consisting of physiologists and sound engineers, including the inventor (Harold Burris-Meyer) of the new stereophonic system that made possible the recording of music for Walt Disney’s Fantasia. In a short excerpt of archive footage from an army training film during World War II, an engineer is shown cutting a “dubplate” of sound effects such as bulldozers, the construction of a bridge, and an armored column of troops. The records were then filed at a library at the Army Experimental Station and rerecorded in sequence onto wire. The engineer is filmed mixing down a soundtrack onto a wire recording using three turntables.1
This sonic deception involved the generation and distribution of sounds to produce the sonic experience of the battlefield in order to confuse, mislead, or distract the enemy. Blending actual recordings and artificially generated noise, it was targeted at the enemies’ ears and listening devices. The less effective the enemy’s visual capabilities, the more powerful sonic deception could be. Visual concealment by smoke or the dark of night obviously assisted the process. Moreover, climate and geography intimately affected the range of signals.2 Based on the intricate logic of sonic effects, the sound ranging of the enemy attempted to estimate the distance of the sound sources. For example, the Doppler effect dictated that sound increasing in frequency was approaching and sound decreasing in frequency was retreating. Such a manipulation of frequency was therefore deployed to trick the enemy or was deliberately avoided in the recording of sound effects.3 Yet, in practice this was unreliable, and it required the enemy to remain relatively static.
These techniques of sonic deception derived from an accident. It was noticed that when dive bombers came plunging from the sky, with their characteristic “screaming whine caused by a siren deliberately designed into the aircraft... it instilled a paralyzing panic in those on the ground.... For Division 17 of the National Research Defense Committee, the lesson was clear: sound could terrify soldiers.... So they decided to take the concept to the next level and develop a sonic ‘bomb.’... The idea of a sonic ‘bomb’ never quite panned out, so the engineers shifted their work toward battlefield deception.”4 Sonic deception therefore emerged out of the power of audible vibrations to generate an affective ecology of fear.
This sonic manipulation of the enemy involved a number of key tactics of frequency to produce virtual sound. To create a phantom army in sound, its presence had to be fabricated using what is often referred to as the “acoustical intimacy” of binaural hearing, that is, the ears serve as two input channels for sound and together create a whole virtual field:
Hearing is imperfect and can be fooled, especially when other senses, such as sight, are also involved. We do not hear in the precise way an oscilloscope measures sound waves. How and what we hear depends on context, both physical and emotional.... Presence emerged as the complex result of improvement in several key components of the sound recording and playback system. First, the recordings themselves were purer, clean of masking sound or obtrusive background noise. Second, the individual sound effects were mixed into multiple channels and then played back through multiple speakers, both on a single vehicle or vehicles separated by hundreds of yards. The psychoacoustical effect was that, as sound moved between speakers, the listener heard a phantom sound, a sonic illusion, but one that did not jump from one sound source to another. Rather it lingered in the space between the two speakers, creating a sense of spatial reality for the sound.... The speaker itself evolved from a rigid metallic horn that gave off volume but sounded tinny and flat, like a megaphone. Now a larger, flexible speaker came into play. Its fifteen-inch diameter allowed it to handle “bass” or low frequency sound waves ... frequency response was richer... natural harmonics of a sound, sometimes called overtones ... to the human ear, those overtones, which resonate at mathematically predictable frequency intervals, and not usually audible as separate sounds ... the impression that sound was coming not just from the speaker itself but also from beside it and behind it.5
As sonic deception became taken more seriously, it fed into the improvement of speaker technology. As Bell Labs noted, in World War II, the new “military acoustic devices were not just copies or minor physical modifications of existing instruments ... but rather basically new designs.” In fact, because of their newfound fidelity to presence, they would “become popular in the civilian world after the war in stereo hi-fi systems and studio monitors.”6 Aside from new innovations in sound technology, older devices such as the magnetic wire recorder were dusted off to solve the problem of skipping phonograph needles in mobile vehicles in the field. During the 1930s, Hitler’s Ministry of Information and Propaganda was deploying wire recorders to deceive listeners about his actual location by playing prerecorded speeches on the radio and pretending that they were live broadcasts. The tactics and technologies of sonic deception therefore add yet another instance to Kittler’s notion that popular sonic media entail the “misuse” of military technologies. And these techniques of virtual sound serve as a precedent to deployments within the U.S. invasions of Iraq and more recent military research into directional sonic lasers.