The Walls of Jericho

The ancient biblical story of the battle of Jericho tells of how the Israelites, led by Joshua, caused the walls of the city to come crashing down by repeated blasts of horns, which shook them to pieces. The development of new technologies in the nineteenth and twentieth centuries showed that sounds do indeed have the potential for enormous destruction - or for more constructive uses as tools. Perhaps unsurprisingly, science fiction has explored the range and scope of potential uses of sonic devices, reflecting our changing scientific understanding of the science of sound.

Sonic Offence 

A common and recurrent theme in science fiction is the use of sound or ultrasound (waves with frequencies above human hearing) in hand weaponry or artillery, such as sonic blasters, rifles or canons. Such devices use sound waves to generate resonances in materials, causing vibrations (oscillations) and effectively shaking them apart. Strong enough sound waves will cause anything to vibrate (as anyone who has stood near a large enough loudspeaker can testify). However the structure of the nearby object, supported by the scaffolding of atomic or molecular bonds, and the tensile strength inherent in materials, will try to dampen vibrations, keeping the movement from building up. Resonance is a situation in which the frequency of the sound matches some natural vibration in the object’s structure. In this case, rather than resisting movement, the structure of the object responds to it. No energy is lost in resistance, and the vibration builds up until it is strong enough to break through whatever scaffolding or bonds gives the object its structure.

The destructive power of resonance and other vibrations has been repeatedly demonstrated. Soldiers crossing a bridge are routinely ordered to break from marching in step to avoid building up vibrations at a single frequency. More dramatically, the Tacoma Narrows suspension bridge in Washington state, USA, was destroyed within a few months of opening in summer 1940, when the wind blowing down its valley (basically a whistle of sound) caused a massive twisting and oscillation in the bridge’s deck. This eventually broke apart and collapsed into the valley below. Importantly, this event was captured on film, becoming a textbook example of positive reinforcement of oscillations and their destructive potential.

The frequency of destructive sound waves can be tuned to vibrate either organic material (such as flesh and bones) or inorganic material (such as buildings or other structures). Examples of the use of this effect in science fiction include many hand guns, which are often used without detailed explanations, such as the Geonesian sonic blaster in the Star Wars universe (e.g. The Phantom Menace, Film, 1999), sonic guns used in season 4 of Voyage to the Bottom of the Sea (TV, 1964-1968), sonic rifles used by the Alliance in Firefly (TV, 2002) and the Weirding Modules used in the 1984 movie adaptation of Dune (dir. Lynch [1]). A novel ultrasonic vibrating weapon is invented by Professor Calculus, and must be defended by Tintin and Captain Haddock, in The Calculus Affair (comic, 1956).

In some cases, the use of sonic weapons extends from hand weaponry to larger scale artillery. An early example can be found in Rudyard Kipling’s 1912 science fiction novel As Easy as ABC. In this vision of 2065, humans live extended lives of comfort, with a low population density, a low birthrate and strong taboos regarding privacy, under the guidance of the Aerial Board of Control. When one group of dissidents advocates a return to crowd rule and direct democracy, they are combatted by an aerial bombardment of both sound and light:

No lights broke forth, but the hollow of the skies made herself the mouth for one note that touched the raw fibre of the brain. Men hear such sounds in delirium, advancing like tides from horizons beyond the ruled foreshores of space.

“That’s our pitch-pipe,” said Arnott. “We may be a bit ragged. I’ve never conducted two hundred and fifty performers before.” He pulled out the couplers, and struck a full chord on the Service Communicators.

The beams of light leaped down again, and danced, solemnly and awfully, a stiltdance, sweeping thirty or forty miles left and right at each stiff-legged kick, while the darkness delivered itself - there is no scale to measure against that utterance - of the tune to which they kept time. Certain notes - one learnt to expect them with terror - cut through one’s marrow, but, after three minutes, thought and emotion passed in indescribable agony.

Here the effect is more psychological than physical, although the victims are temporarily deafened and blinded. While the goal of the ABC in this instance is not to kill, we are left in little doubt that they could and would if necessary.

Other examples are fairly common. The “multiple resonance detonator” deployed in an episode of television spy-fi series The Girl from U.N.C.L.E. “The Dublegratz Affair” (1967), massively over-amplifies the music of a rock group, to cause a glacier collapse in an eastern european country. The dialogue included a discussion of resonances, illustrated by images of the famous Tacoma Narrows Bridge disaster. By contrast, the 1986 film Biggles - Adventures in Time (dir. Hough) [2] is a time travel romp in which a modern salesman tries to stop the Germans of World War I from developing a sound cannon that could change the course of the conflict.

Moving from the past to the future, the Noise Marines in the science fictional table-top game Warhammer 40,000 (game, 1987 onwards) are post-human, heavily augmented both genetically and electronically and extremely sensitive to sound. They experience euphoria when exposed to the loud noises of battle and have developed an extensive sonically-based artillery, much of it built into their power armour, including sonic blasters, doom sirens and a larger blastmaster.

Also benefiting from inbuilt sonic weaponry are the intelligent and sentient machine lifeforms of the Transformers universe (Toys, TV, Films, 1984 - present). Canonically originating on the planet Cybertron, but able to adapt their forms to mimic Earth machinery, each adopts a form and weaponry in keeping with their individual aptitudes. Characters using sonics offensively include Soundwave (who can record and manipulate electronic frequencies as well as sounds), Thundercracker (whose aircraft form uses sonic booms as a weapon) and Starscream (another aircraft who can use high frequency sound offensively).

While all of the above are weapons affect relatively small regions at a time, there are also science fiction examples in which sound weaponry is used on a planetary scale. An interesting case here is provided by the 1962 marionette animation television series Space Patrol, written and produced by Roberta Leigh. This is set in an imagined Solar System in which each planet is occupied by its own intelligent life, and Venus, Earth and Mars form a cooperative government. However when civilisations are found on Neptune and Uranus, they prove to be hostile. Amongst several attacks launched against Earth are a “jitter ray” which causes buildings on Earth to shake and robots go crazy, and which builds over time (episode “The Jitter Waves”). The twenty-four hour cycle of this vibration suggests it is being caused by a ray from elsewhere in the Solar System. A sound wave, which is a movement of gas or fluid molecules, cannot propagate through vacuum, but long-wave radio waves can start vibrations when they hits the top of the atmosphere and are absorbed by the gas there. Ultimately it is traced to the Uranian plant people and a reflector in space used to direct the destructive power back to its source.

The science in Space Patrol, while interesting, frequently doesn’t bear close inspection. In the episode “Destruction by Sound”, a teleportation method using sound to break down a person to information is trialed, and causes a person to start talking backwards. The characters use a “super ultrasonic machine” as a medical tool to try to reset her brain to speak forwards. It’s fair to say, this lacks a certain amount of plausibility, even if it does presage the use of ultrasonics in medicine. The same technology is then immediately used to destroy an “electronic brain” that is using robots to enslave an alien race.

Sonic defence and control

While there is sometimes a fine line between attack and defence, there are a number of examples in science fiction of sound waves being used for defence or for non-lethal control of individuals rather than as aggressive weapons.

 Arguably the example from As Easy as ABC could be considered a police action, although the tone is certainly ruthless. In other examples, such as, Police Action (short story, 1948, part of the Paratime series), H Beam Piper equipped his police force with both lethal and non-lethal weapons, with ultrasonics providing the latter:

A couple of policemen in green uniforms, with ultrasonic paralyzers dangling by thongs from their left wrists and holstered sigma-ray needlers like the one on the desk inside the dome, were kidding with some girls in vivid orange and scarlet and green smocks.

This is fairly typical for stories in which sonic guns are used as defensive or population control weapons. They appear throughout science fiction, including in television examples such as SeaQuest DSV (TV series, 1993-1995), in which sonic disruptors and pulse guns are used as a police weapon and equipped with stun settings (although in later series these were replaced with energy weapons), in films like Minority Report (film, 2002, dir. Spielbergl although not in the 1956 Philip K Dick story from which it was adapted) and in stories like Randall Garrett’s The Hunting Lodge (Astounding, July 1954) and Larry Niven’s Known Space saga. In Niven’s The Slow Weapon (If magazine, Feb 1967, later adapted as an episode of Star Trek Animated called “The Slaver Weapon”, 1973) a sonic stun setting was one of a number of forms possible for a weapon, left behind by a long vanished race, which had been designed as a tool for a spy, while the Kzinti antagonists also possessed sonic stunner technology.

Technology for sonic stunning (i.e. harmless rendering unconscious) has proved far more elusive than science fiction originally anticipated. However the idea of using sound for crowd management is not as far fetched as it might seem. LRADs or Long Range Acoustic Devices are ‘sound cannons’ that project high volume noise to disperse crowds. Their use is controversial due to their indiscriminate nature and the pain they can cause when used on potentially legitimate protests.

Science fiction includes examples of sonic equipment used for personal defence by individuals who are capable of generating soundwaves that may harm others but are more often defensive. In the Transformers universe, this includes Autobot Jazz, whose vehicle form includes large bass speakers that are used to create a low frequency sound bombardment. The television series Farscape (1999-2004), which follows the adventures of a disparate group of alien fugitive, includes Jool, a young woman who can produce an ultrasonic scream capable of melting metal, whereas in the X-Men (comics and spin-offs, 1963 onwards) characters with innate sonic abilities include Banshee, whose sonic scream can be used for weapon, defence or even sonar or propulsion.

More idiosyncratic uses of sonic devices for control of individuals are a particular feature of spy-fi television series. The Champions, for instance, featured an episode (“The Invisible Man”, 1968) in which a banker was driven to the point of insanity by what appears to be a haunting presence. It proves that both the banker, and later one of the Nemesis team, has been implanted with a miniaturised speaker in the inner ear which broadcasts both voices and loud noises aimed to induce insanity. The Avengers also used infrasonic broadcasts for personal control of the staff of an air force base in “The Hour That Never Was” (TV episode, 1965) and also to produce the illusion of an invisible man through the invention of an ‘audio-telescope’ in “All Done with Mirrors” (TV episode, 1968). The operation of all these devices remains rather unclear, and often physically implausible.

Sonic tools

While the destructive power of excessive vibrations is proven and widespread in SF, the use of sonic tools for more constructive purposes is also common. Perhaps naturally, given its status as proven and already extant technology, sonar technology is a basic feature of science fictional super-submarines such as Stingray (TV series, 1964-5), Seaview (from Voyage to the Bottom of the Sea) and SeaQuest DSV. While often of higher resolution and longer range than current technology, these remain plausible. More generally the use of sound waves for remote sensing is now relatively commonplace [3] both for investigation at a distance and for fine-scale non-invasive analysis of flaws or defects in a material.

Science fiction involving archaeologists or geologists on alien worlds often includes examples of using sonic or ultrasonic remote sensing for initial investigations. An example that does not involve submarines can be found in the television series Doctor Who (1963 onwards). The 1979 serial “The Power of Kroll” involves the Doctor and his companion Romana in a journey to a relatively primitive world in search of a powerful artefact. The human colony on the world is refining methane from swampland, over the objections of the natives, who fear angering their god Kroll. A dramatic sequence, straddling an episode-ending cliffhanger, involves the human scientists using sound to scan the ground sediments, revealing the enormous squid-god Kroll gradually rising to the surface.

Also based on current technologies is the use of ultrasonics in medicine. Ultrasound imaging of the interior of the body was demonstrated as early as the 1940s, and obstetric ultrasound (imaging of pregnant women) became relatively common in UK hospitals from the 1970s, with technology developing rapidly into the 1990s, by which time it was routine. It is now ubiquitous. The use of ultrasound medical imaging in science fiction reflects this trend, becoming relatively common as an assumed technology from the early 1990s onwards, while being rare before this point.

An interesting recent example of the medical use of sound can be found in the recent Star Trek: Discovery episode “Whistlespeak” (TV episode, 2024). Here the Discovery visits a desert planet with one green area maintained by a weather control system. When a native woman suffers dust-congested lungs, the officers are conflicted as to whether it is ethical to use advanced sonic tools in this Prime Directive situation. This proves an unnecessary dilemma as the native peoples have themselves developed a form of therapy which uses an ultrasonic resonance generated from rubbing the rims of specially designed bowls to do the same job. It’s interesting to note that the non-invasive medical scans of the original 1960s series of Star Trek (and other contemporary fictions) did anticipate medical ultrasound technology, and may in part have helped inspire its miniaturisation and application in small handheld devices. However the underlying principles of medical devices in the twenty-third century were never explored in any detail.

Another now-current technology which appears in science fiction is sonic cleaning. In their current application as ultrasonic cleaners for scientific, medical, precision engineering and technical equipment, sonic baths involve submerging items in a cleaning fluid through which ultrasound propagates effectively in order to lift dirt, dust and debris from the surface through vibration. The use of a fluid is a recognition that sound waves travel faster and more efficiently in dense materials than in sparse ones such as an atmosphere. However in science fiction, sonic cleaning is often shown as effective in atmosphere alone and often used in settings in which water and other fluids are scarce.

Sonic Showers used for personal cleansing have been a feature of the Star Trek universe since the release of Star Trek: The Motion Picture in 1979, with the devices appearing in storylines in Star Trek: Voyager (e.g. “Live Fast and Prosper”, 2000) and in Star Trek: Lower Decks (e.g. “Kayshon, his eyes open”, 2021). These appear to use vibration directly, without additional fluid, to remove surface dirt, and applications such as sonic toothbrushes have also been seen (e.g. Star Trek Enterprise episode “The Catwalk”, 2002). The Vorkosigan Saga of Lois McMaster Bujold (novels and short stories, 1986-2018) also describe sonic showers as normal on space vessels which are less abundantly supplied than those in the Star Trek universe, and where water conservation is essential. This universe also includes sonic toothbrushes [4], laundry and toilets and decontaminators. However their limitations when it comes to personal cleansing are also apparent. As we’re told:

Miles entertained himself with a gruesome vision of what could happen if the programming on the elaborate sonic tooth-cleaner ever went awry. (The Vor Game, novel, 1990)

Sonic cleaning is also mentioned, albeit as a background feature in From the Moon, with Love by Neil Shapiro (F&SF, Feb 1970). This strange little story imagines the last two humans as naive clones maintained by robots in two opposing fortresses on the Moon, brought together as a breeding pair by aliens who want to see another intelligent race in existence before accepting extinction. While the main theme of the story does not revolve around sonics, we’re told that:

It would be poetic to say that first he scraped off a two centuries’ layer of dust”... “However, the suit was spanking clean and its chrome parts glistened almost with as much of a sheen as Hillman’s hide — thanks to the always-humming, ultrasound cleaning room the suit had been stored in.

In most of the above aspects, representations of sonic technology have paralleled those in scientific and real world use, even if imagining more powerful examples. However SF has also explored more exotic and less explicable uses of sonic waves as tools.

The classic example, of course, is Doctor Who’s sonic screwdriver. First introduced in the 1968 serial “Fury from the Deep”, it was initially used as the name suggests: it was able to create a sound wave that would cause screws to rotate and so unfasten themselves (or vice versa). In the later seasons of the series, through the 1970s and 80s, and again after 2005, it was represented as a more versatile, multi-function tool which could open locks, resonate concrete (although not wood), create holes, send signals, detonate explosives, scan and diagnose systems or individuals and control technology amongst many other uses. To do so, its description widened to include all forms of wave phenomena (primarily electromagnetic) as well as the acoustic waves initially suggested by the title. The operation of the sonic screwdriver is best covered under “advanced technology indistinguishable from magic” but it is tempting to imagine that the original idea was to create a vibration that included a rotational torque along a screw thread, perhaps due to air pressure waves forced along the thread (although the mechanism for this is unclear), or to vibrate the internal components of a lock until the tumblers were released.

Similar sonic tools appear elsewhere in science fiction. The vigilante Green Hornet (a crime fighter in the mode of Batman) had an ultrasonic “stinger” in its 1966-1967 television incarnation, which apparently was also occasionally used as a screwdriver, as well as opening doors and starting fires. Alongside its sonic showers, handweapons and medicine, Star Trek also featured sonic drills (e.g. DS9 episode “Prodigal Daughter”, 1999; Voyager episode “Live Fast and Prosper”) which penetrate by breaking up minerals through vibration - another technology which is now in real world use. Animated series Thunderbirds Are Go is notable for equipping its multi-purpose rescue vessel Thunderbird Two with sonic wave generators which are used to extinguish a fire in the world’s tallest building in the episode “Inferno” (2017). Again, sonic fire suppression (as well as ultrasonic non-invasive scanning of more conventional fire extinguishers) is a real-world technology reflected on screen. This works by sending a pressure wave through the fire front, which disrupts the flow of oxygen and any convection cells set up by the flame.

An interesting example of a sonic technology anticipated in fiction well before it came into everyday use is in the area of noise cancellation. As early as the nineteenth century, it was well understood that combining a wave with a version of itself in which the phase is shifted will result in it cancelling out - i.e. the crest of one wave will meet the trough of the other, resulting in a level surface.

Robert Heinlein used this concept explicitly in his 1956 novel Double Star:

 The suite was equipped with a hush corner, enclosing the autograph and the phone. Broadbent took Dubois by the arm and led him over there; they stood and talked urgently.

Sometimes such facilities in public places like hotels are not all that they might be; the sound waves fail to cancel out completely. But the Eisenhower is a luxury house and in this case, at least, the equipment worked perfectly; I could see their lips move but I could hear no sound.

Exactly the same physics underlies the Fenton Silencer which appeared in the near-contemporary Silence, Please by Arthur C Clarke (which appeared in Tales from the White Hart, 1957):

It consisted of a microphone, a special amplifier and a pair of loud speakers. Any sound that happened to be about was picked up by the mike, amplified and inverted so it was exactly out of phase with the original noise. Then it was pumped out of the speakers, the original wave and the new one cancelled out, and the net result was silence.

Unfortunately for Mr Fenton, his invention is used by a student for a practical joke, and its operation proves to rely on storing the energy being cancelled by the sound waves rather than dissipating it - as a result it overloads and explodes.

The adolescent inventor Tom Swift Jr considered still more ambitious noise cancellation (amongst other applications of sonics) in the novel Tom Swift and his Sonic Boom Trap (1965, published under the series pseudonym Victor Appleton II). Again, amidst explanations of wave interference, Swift perfects a ‘silentenna’ (a wave-inversion cancellation device that works at short wave) in the first chapter, but his objective is to fit aircraft with devices that will nullify the sound of any sonic boom they generate at source. This is unlikely to work, as the sound of the sonic boom shock is generated some distance from any equipment the aircraft might carry, and the energy requirements would be colossal if it were even possible. Nonetheless, through a series of adventures, his device proves to have other applications when antagonistic forces launch sonic attacks and brainwashing against the wider population. In an interesting nod to the technical context of the work, the plot kicks off with Swift attending an academic conference on noise reduction, and there are mentions of studies on the effects of noise stress on animals. In fact, in a realistic touch, the need for a piezoelectric crystal to detect and produce sound [5] is a key plot point, and the ultimate success of Swift’s device relies on a highly responsive transducer developed by his father (and earlier protagonist of his own series of novels in the 1910s) Tom Swift Senior, which converts energy to sound.

Practical descriptions such as these built on and fed into countless other less well explained noise suppressors, cones of silence and privacy fields in science fiction both earlier and later. Noise cancellation through wave interference is a technology now common in headphones, microphones and other sound devices. However the practical application of this very straightforward principle was forced to wait for development of microphone and speaker systems with highly sensitive and rapid response, or for computer systems capable of distinguishing between desired and undesired sounds. Even now noise suppression is often limited, and works best on constant rhythmic background (such as engine noise) which can be modelled, predicted and a suppressing wave transmitted straightforwardly.

Ultra Sound

Speculative stories of shaped sound and sonic tools have appeared alongside technical and engineering development of the very technologies they described. While many of those, particularly involving noise cancellation, medical imaging, starting fires or cleaning materials with vibration, are based on very straightforward classical physics, some - such as sonic screwdrivers still lie well beyond our capacity. Indeed it is not clear what physical principles many functions of advanced science fiction technologies could be based on in some cases, or how they could be rendered powerful, specific and compact enough to be effective in others.

On the other hand, the full breadth and variety of applications of sound and ultrasound in contemporary sensing, flow-monitoring, probing, medical (and veterinary) applications and chemical processing has neither been anticipated nor reflected in science fiction. Many of these applications are still relatively little known and used in highly specialist fields. Their development relied on modern computing and on the development of transducers capable of high frequency controlled vibration such as piezoelectrics (as anticipated by Tom Swift of all people!). Their explanation in the context of science fiction narratives would often be complex and distract from storytelling rather than enhancing it.

However science fiction has, perhaps, contributed to inspiring at least one application of sonic technology. Research at universities in the UK has led to the development of arrays of speakers which are carefully controlled so that their signals arrive in phase (i.e. with peaks lined up rather than cancelling) at positions desired. It’s perhaps obvious that these phased signals can be used to push an object as the sounds are formed from pressure waves, and that this can even suspend an object above the speakers in mid-air. However it’s perhaps less intuitive that since the first proof of concept of such devices, scientists have used them to create vortices that can rotate an object held above the speakers. By producing a low pressure region between the speakers and the object, and concentrating the sound peak beyond it, they have also generated a device which uses sound to pull an object rather than push it.

The parallels to Doctor Who’s sonic screwdriver and Star Trek’s tractor beam are apparent, and both the scientists involved and the press haven’t hesitated to make them [6]. Of course, a sonic tractor beam (which, by its nature, requires a gas or fluid in which sound can propagate) cannot be used in vacuum as seen in most SF, but it is still a fascinating example of an application inspired from the science fictional universe which will likely find increasing applications over the coming decades in precision manipulation of objects or biological samples. Other scientists have been working on similar technologies using laser light (which would work in vacuum but is much more challenging to align and power).

Ultrasound and sonic technology is an area which has developed in parallel with but in different directions to those anticipated in SF, and which is perhaps more persuasive in modern industry, medicine and science than many realise. Shaped sound, as used in sonic tractor beams, remote sensing and chemical processing, is an extremely flexible tool for manipulation and interpretation of materials. Its analysis has been revolutionised by the computer capacity to both manipulate arrays of sound generators and to interpret signals received from complex transmission and reflection networks. They are a far cry from the simple horns used against the biblical walls of Jericho. Many of today’s technologies would have been dismissed as sheer science fiction as recently as fifty years ago, and some have been inspired by that science fiction. It will be interesting to see where the next fifty years will take this field.