Numer 24 / 2014

Projecting the Sound – Listening to Axis Mundi

Pamela Granatowski

Anis changed into his white jellabiya, sat on the balcony overlooking the Nile. (…) His eyes were sliding on the calmmand smooth water surface, as if frozen in stillness. He knew that water that doesn‘t glisten and wave is a perfect carrier of human voices inhabiting the other side of the river in a long row of barges under the acacia branches.

Naguib Mahfouz, “Adrift on the Nile”

 

Although we owe the first scientific evidence for the fundamental links between sound and its environment to the famous 17th-century experiment with an air pump conducted by Robert Boyle and Robert Hooke, there is no doubt that investigations and observations as well as practices and methods of applying these correlations could be noticed long before the year 1662 – the year of publishing the detailed account of the two English researchers’ experiences under the title “New Experiments Physico-Mechanicall Touching the Spring of the Air, and its Effects”. We learn about people’s intuition, knowledge and deeper awareness of the complexity of these relations from the history of philosophy and science which – often through experiments – presented successive attempts to understand how sound behaves after being emitted, how it is propagated and what a%ects its propagation. But we also learn about it from the history of architecture as well as anthropological insights into people’s cultural practices. Certainly, it has always been known that sound does not simply propagate in air – what would that mean anyway? Further reflections – both theoretical and practical – over “the behaviour of sound” offered insight into not only its ontology but, above all, its functionality. Questions regarding the essence of what sound is and how it could be taken advantage of constantly overlapped. This overlapping composed a specific history of what is invisible though effective and opened entire chapters
of experimental usages of sound in processes of symbolisation, socialisation or socio-physical deffinition of what is common for air, water and solid substances.
In the 4th century BC, Aristotle argued that a sonic phenomenon requires presence of two bodies and space between them which enables the event to take place. He claimed that this space could be both air and water, although neither the former nor the latter could be considered the source of the sound itself.

Actual sound requires for its occurrence (i, ii) two such bodies and (iii) a space between them; for it is generated by an impact. Hence it is impossible for one body only to generate a sound—there must be a body impinging and a body impinged upon; what sounds does so by striking against something else, and this is impossible without a movement from place to place. […]

Further, we must remark that sound is heard both in air and in water, though less distinctly in the latter. Yet neither air nor water is the principal cause of sound. What is required for the production of sound is an impact of two solids against one another and against the air. The latter condition is satisfied when the air impinged upon does not retreat before the blow, i.e. is not dissipated
by it.

That is why it must be struck with a sudden sharp blow, if it is to sound — the movement of the whip must outrun the dispersion of the air […]

An echo occurs, when, a mass of air having been unified, bounded, and prevented from dissipation by the containing walls of a vessel, the air originally struck by the impinging body and set in movement by it rebounds from this mass of air like a ball from a wall. It is probable that in all generation of sound echo takes place, though it is frequently only indistinctly heard. What happens here must be analogous to what happens in the case of light; light is always reflected — otherwise it would not be diffused and outside what was directly illuminated by the sun there would be blank darkness; […]

It is rightly said that an empty space plays the chief part in the production of hearing, for what people mean by ‘the vacuum’ is the air, which is what causes hearing, when that air is set in movement as one continuous mass; […] Air in itself is, owing to its friability, quite soundless; only when its dissipation is prevented is its movement sound. The air in the ear is built into a chamber just to prevent this dissipating movement, in order that the animal may accurately apprehend all varieties of the movements of the air outside. That is why we hear also in water, viz. because the water cannot get into the air chamber or even, owing to the spirals, into the outer ear. […]

It is also a test of deafness whether the ear does or does not reverberate like a horn; the air inside the ear has always a movement of its own, but the sound we hear is always the sounding of something else, not of the organ itself. That is why we say that we hear with what is empty and echoes, viz. because what we hear with is a chamber which contains a bounded mass of air. Which is it that ‘sounds’, the striking body or the struck? Is not the answer ‘it is both, but each in a different way’? Sound is a movement of what can rebound from a smooth surface when struck against it.

Aristotle, De Anima (On The Soul), Chapter 8

The tradition symbolised by the words of Aristotle became the central point of reference for theoreticians in at least the next few centuries. Already in the 6th century, a Roman philosopher Boethius, who – not without reason – was a translator of Aristotle’s writings, documented a few statements which developed the Athenian’s ideas. The most important among them was a conviction that human perception of the acoustic field is connected with physical properties of air. Any change of meteorological conditions may easily cause 10-20 dB oscillations in the sound level. Moreover, the longer transmission path, the greater sound level variation. According to Boethius, in plain air, the mechanism of sound propagation is affected by several factors including:
a) Meteorological conditions (wind, precipitation, temperature changes, etc.)
b) Absorption of sound by the atmosphere
c) Type and shape of the land (absorption of sound by the ground, reverberation)
d) Obstacles (buildings, obstacles, greenery, etc.)

The first mathematical theory of sound propagation in the history was formulated by Isaac Newton and is not very remote from Boethius’ intuitions.The tradition established by Aristotle and Boethius, according to which the sound is thought of as “a blow of air”, was transposed by Newton in his “Principia. Mathematical Principles of Natural Philosophy” (1687) into mechanistic interpretation of sound as “compression” of impulses transferred by neighbouring globules. This approach enabled the first analytical presentation of the equation for the speed of sound in air, which was based on Boyle’s law 1. Propagating in air, sound causes its rapid compression and decompression – fast enough to occur without heat exchange with the environment, i.e. being an adiabatic process. On the grounds of this statement, Isaac Newton derived an equation for sound speed in gases, also taking advantage of the ideal gas law stated by Clapeyron. His concept was further developed in the 18th century by Leonhard Euler, Joseph-Louis Lagrange and Jean Le Rond d’Alembert. In 1727, Euler completed his PhD thesis on the physics of sound, referred to simply as “De Sono” in which he dealt extensively with the physics of sound propagation. Euler explains in it what atmosphere is composed of, treating the compression theory taken from his teacher Johann Bernoulli as the foundation for the thesis’ assumptions. Euler also announces – without evidence – an equation for speed of propagation and on its basis, he derives numerical values correct of the order of magnitude for air.

Chapter I.
Concerning the Nature and Propagation of Sound

§ 1. The explanation of sound by the old philosophers was very obscure and confused, so much can be understood from their writings that have come down to us. Some were of the opinion, like Epicures [341-270 B. C.], that sound emanated from a pulsating body rather like the flow of a river; while others with the foremost of the Latin writers, believed with Aristotle, [384 – 322 B. C.] that sounds were formed from the breaking of the air which arose from the more violent collisions of bodies. Among the more recent commentaries, Honoré Fabri [1608-1688], and Descartes [1596-1650], discovered that sound consisted of tremors or vibrations of the air, but their reasoning concerning these vibrations were equally confused. Newton [1643-1727], with the sharpest of minds, considered the matter with more care, and undertook to set forth an explanation especially for the propagation of sound, truly with much more success. A determined effort has been made [by me] to grasp the difficult matters involved in an understanding of the nature of sound, which are set out in the two chapters of this dissertation. In the first chapter it becomes apparent, after some careful thought, what the nature of sound really is, and how it is propagated from one place to another. Moreover, in the following chapter, three sources of sound are to be considered.

§ 2. However, before this work on sound is undertaken, certain facts relating to air in the generation of sound are first to be related. I regard air as consisting of small globules, in a state of compression from the incumbent atmospheric weight, and this compression is relieved to a great extent with elevation, as the force of compression diminishes with height, so that the particles can restore themselves to their natural state. Thus, the weight of the air above compresses the air below, and the air globules are not allowed to be extended. The elastic force of compression on the air globules is equal to the weight of the atmosphere; on account of which one can measure this force by experiment, which truly is equal to the maximum weight of the atmosphere present. This weight is equal to a column of mercury of height 2460 scruples or thousandths of Rhenish feet [One Rhenish foot is equal to 313.8355 mm], and I will always adhere to these measurements in the following text; if the atmosphere has a smaller weight, equal to a column of mercury of height 2260 scruples, then this too can be taken as equivalent to the elastic force of the air [at a greater altitude]. Indeed, the weight of the air has been determined with the aid of pneumatic pumps; and the ratio of the specific gravity of quicksilver to the specific gravity of the warmest air has been observed to be in the ratio 12000 to 1; while for the coldest air the ratio is around 10000 to 1.

§ 3. If we consider one of a series of air globules to be compressed more than the rest, then that globule will dilate according to the law discussed above, while the surrounding globules become compressed by the force acting on them from the dilation of the single globule, which in turn compress others further away, as the globules scattered at a distance experience a little of the [original] compression. And by this line of reasoning the sound is transferred to other places. But, concerning the motion by which the globule considered expands out, after coming to rest relative to the others, it then returns suddenly and is unable to be confined, as it has been extended excessively; hence it is again compressed with respect to the other globules, yet again excessively. Thus each one of the not too distant globules is itself dilated in this way by the trembling motion of that first globule considered, and in this manner each globule is constrained to move. [Thus, the physical idea of a central source consisting of an air globule executing an S.H.M. is presented, with a time delay or phase shift for neighbouring globules ; there is no physical argument presented for the reality of such globules, which are a convenient figment of the imagination.] But such a vibration of the globules of air nearby ought not to occur for globules of a very small size, and which hence depend on an indefinitely short
time for a single oscillation; therefore innumerable oscillations or undulations with a finite period are to be given out by a globule in the manner prescribed, since truly the motion of any such globule of continually decreasing size cannot happen. Moreover, a finite time is required for perception by our senses, and it is not possible for sound to consist of a vibratory motion of that kind in the air.

§ 4. Then at last the sound is produced by the same globule, from the force exerted on other globules, with finite intervals placed between those allowed to have denser compressions. It is of course required in order to produce the sound, that the same globule is alternately contracted and relaxed, and indeed the time for these oscillations should not to be indefinitely small, but finite, in order that the number of these vibrations or oscillations for a given time can be determined. [Note: Mersenne, in his Harmoniae (1635) had already set out tables of frequencies associated with musical scales, and determined the speed of sound experimentally.] Of course the number of pulses arriving on the ear from an organ note in a given finite time can be expressed numerically.

§ 5. With the time now noted for which the sound is present, it is easy to explain the differences of sounds; here I will only distinguish between the principal kinds. Generally there are loud and soft sounds. A sound is loud or violent when the compressions of the air globules are stronger, and a sound is soft or small when these compressions are weaker. When the sound made by the oscillating globule is propagated by the communication of the compressions with each of the globules placed around it, the number of these increases in the ratio of the square of the distances from the place of origin, and the strength of the sound decreases in the inverse square ratio of the distances, unless perhaps
the sound is augmented from elsewhere. The distinction between notes of low and high tones lies in the nature of the maximum duration of the movement. The case for low notes occurs when the vibrations of the air globules follow each other in turn more slowly, or for a given time the undulations are sent out less frequently. Moreover, the note is of a higher tone when the vibrations have shorter delays placed between them, in order that more oscillations are carried out in the same time. Hence the notes, with respect to low and high notes, are in the ratio of the number of oscillations made in a given time interval.
[…]
§ 7. A sound is also either simple or composite. A simple sound [or note] is one in which the vibrations have equal distances between each other, and they are of equal strength. A composite sound is constructed from many simple sounds produced at the same time, and this sets up either concordant or discordant sounds. Concordant notes [or chords] are perceived as being produced by simple sounds or notes maintaining the simplest ratio between the components, such as two as in the octave, or as one and a half as in the musical fifth, etc. On the other hand, the dissonant [or discordant] sounds have their components in a more abstruse ratio, such as two superimposed fractions as in a three tone.

Leonhard Euler, De Sono

Even if sound propagation theories of the 18th century were incomplete, most of their following variants could be perceived as improvements of the ones proposed by Euler and his contemporaries. Mathematical concepts were used to explain acoustic phenomena as in the case of Reynolds and Rayleigh’s research in the 19th century, when sonic phenomena were, directly or indirectly, treated as a result of developing the mathematical theory of waves. John Tyndall – about whom I will write more later – drew a virtually graphic analogy for sound travels in his famous treatise titled simply “Sound” (1867). The visualisation depicts the following process: a boy A pushes B who pushes C, etc., until the last boy E falls forward. The boys remain in their positions, while sound disturbances go through them. The speed of the disturbances
depends on the boys’ weight and potential obstacles on their way.

All of the above outlined attempts to capture what happens in the air are only an intellectual history of settlements concerning sound propagation. What is more important, however, the knowledge in this #eld was not only – or even not primarily – of theoretical nature. „ere are numerous historical analyses which allow us to notice ways of using the knowledge on sound propagation in architecture, landform, music and social practices. It is practical knowledge which is rarely systematised and almost never laying claim to being universal. It is the knowledge belonging to material culture which, therefore, guards many secrets and poses questions about motivations and intentions – sonic, political or religious as well as those related with social institutions. Nonetheless, there are several cases enabling us to follow or at least acknowledge the history of experiments with sound but also musical worlds of our ancestors – since the earliest preserved examples of human activity.

Research tools for reconstruction of soundscapes from thousands years ago we owe to archaeoacoustics, a rapidly developing discipline of science occupied with analysing sound in the archaeological context. One of its key methods involves following propagation trajectories of sounds which emerge naturally or are artificially evoked at given archaeological sites. Archaeoacoustics, therefore, creates an opportunity to study pre-historical soundscape by treating topography as specific boundary conditions of sonic practices conducted with the help of knowledge about the soundscape-related secular and sacral semantics. It might be assumed that sound was a crucial element during cult rituals and it had probably been perceived as magical at least since the Palaeolithic period. Evidence can be found at sites where we encounter cave paintings, e.g. in France and Spain but also in places associated with rituals such as “singing rocks” in Russia and the British Isles or megalithic buildings scattered all over Europe but not only (see text by Ewa Kozik).
Archaeoacoustic research proves that at archaeological sites, we also deal with acoustic and sonic phenomena which may have their roots in natural geographical conditions which, in turn, a%ected the wind, water or temperature, simultaneously prompting development of the onetime mythology or beliefs but also related practices. Moreover, architectonic localisation of some of the ritual places or temples seems to be, from today’s point of view, deliberately designed or at least to a great extent consciously used, contributing to or even
producing acoustic symbolism or a sonic context characteristic of certain social situations. The examples are countless. An archaeological site – megalithic Easter Aquhorthies in Aberdeenshire – was examined by a group of English scientists: archaeologist Aaron Watson and acoustician David Keating from the University of Reading as well as, convergently, Robert G. Jahn at Princeton. This stone circle with two tankers revealed rich acoustic qualities: the sounds emitted from the centre of the circle were strengthened by reflecting from the circumferential, resonant stones. Found among the stone circle, a flat stone resting between the two tallest vertical pillars seemed to function both as an altar and a stage from where sounds (singing, playing music, speaking) were distributed. These sounds were then reflected from a circle (20 meters in diameter) of megalithic steles 2, using the stone complex or shall we say: simply turning it into a natural loudspeaker. Similar objects were built in the Neolithic period. They could be useful in astronomical observations conducted to follow seasonal weather changes important to onetime agriculture. But they also had their symbolic function related to proxemics. They created spatial representations of hierarchies and they did that also on the acoustic level. What indicates it is the diversity of building materials (granite, porphyry, jasper) which can be found at the site and which must have had in&uenced the acoustics of the complex together with variances of the sound de&ecting surface. The stone “altar” probably constituted the centre of events around which the stronger sound was evenly distributed almost solely within the range of the circle. In those cases – long before Aristotle – sound is perceived and used in its fundamental relation with physical environment, with space de#ned by a) shape (usually circular) and b) material (the type of stone determining behaviour of sound in air). In combination, they define the physical context which activates certain, not entirely explored, functions of sound to given communities, simultaneously heralding the output of Stagirite who was convinced that sound only “happens” in a defined space through the encounter with other bodies.

Even more complicated sound projections can be found in the acoustics of the Neolithic barrows in Scotland. In one of them (Camster
Round, Caithness), scientists experimented with drumming in the chamber of the barrow. Even though the sound could not be heard in the open space farther that than ca. 90 metres, it appeared inside the neighbouring barrow (Camster Long, Caithness) located around 180 metres from the first one 3. On the other hand, in the stone tomb Dwarfe Stane in Orkney – also dating back to the Neolithic period – a human voice resonating inside the tumulus caused an impression of energetic jolts of the rock which were perceptible for people standing on the top (so outside) of the barrow 4. There are also presumptions that during rituals, these places also had sonically active functions to provide events with unknown soundtrack coming “from nowhere”. We can only guess what exactly those sound effects were used for in the above mentioned situations. A presumption that they were intended to evoke different states of mind is certainly justified. Sounds, especially low-frequency ones, affect the entire body, which corresponds with trance. It has been proved that infrasounds play a crucial role in experiencing sound shifts, even though they are below the threshold of being heard by a human ear (< 20 kHz) – they may be detectable as inaudible but physically perceptible vibrations. This type of corporeal experiences might have been considered as healing procedures related with magical rituals 5 On the grounds of existing premises, it seems to be clear that people living in the above mentioned period observed refractions and other sonic qualities in caves and they could try and use acoustic topography in a more controlled manner. Russian and Finnish paleoacousticians, examining “ringing rocks” 6 in the form of stalactites and stalagmites on the shore of the Onega Lake in Russia, discovered that the sound of these rock formations being struck seemed to have been strengthened by refraction from the water surface which made the sound travel even up to several kilometres. They also noticed that many rocks while being struck, made noises resembling bells, drums or gongs. Not only coincidentally, they were marked with rock paintings or carvings. Some archaeologists call such rock formations lithophones. In Canada, at the Mazinaw Lake near Ontario, the Bon Echo Provincial Park is situated – right above the water surface, dozens
of paintings made with ochre spread along the bottom part of the cliff 7. Hundreds of similar places could be found. If Easter Aquhorthies could be understood as an architectonic loudspeaker, cases such as barrows, Dwarfe Stane or ringing rocks could serve as further development or diversification of our collection of “the first PA systems”. It is not only about situations in which refraction of sound has the strengthening function but also when sounds, being defected by natural or architectonic obstacles, reach listeners from places which are different from the place of emission. Effectively, we deal with multi-channel sound projection. The physical process of refracting the sound at the edge of air masses and denser materials such as rocks could result in perceptions understood as auditory illusions. It is one of the most well known acoustic effects studied from ages – echo.
It makes the sound be perceived as if emitted from a completely different place than it actually is, for example, from within the rock, even if it
was only refracted from its surface. This is why echo played a key role in constitution of religious beliefs including the world of spirits located on the other side of the rock wall, at times even trapped within the rock as if being disembodied yet material source of voice.
It was also proved that defected sound can be louder than emitted sound itself and so it may work as natural multi-channel projection. One of
the pioneers of such thinking is a French researcher Iegor Reznikoff who examined resonances and echoes of caves with rock paintings. He also studied engravings from the bronze age found at the lake near Helsinki, Finland, where the caves’ walls covered with images delivered very complicated forms of echo once the sound was emitted from the boat sailing on the lake. According to him, sound was meant to function as a sonar and a distance meter helping explore the cave. Reznikoff even went as far as comparing the perception of space in cave to the one in a mother’s womb 8.

In a prehistoric cave, one of the most impressive experiences is to discover the cave, walking in complete or almost complete darkness, and all while making sounds (preferably vocal ones) and to listen to the answer of the cave. In order to figure out where the sounds come from – from far away or from nearby – and whether there is somewhere a strong resonance or not: all this in order to ascertain the direction in which one may proceed further on. Because our vision is limited by darkness, resonance is the only way to know
how long or deep the space ahead is. This represents one use of the voice and of the hearing as a sonar device, and there is no doubt that Palaeolithic tribes who visited and decorated the caves proceeded in this way; indeed, in irregular shaped galleries or tunnels, neither oil lamps nor even torches light further than a few meters. This sonar method works: in many cases, proceeding into the direction of the strongest answer of the cave will lead to the locations of paintings. This way of moving around in darkness demonstrates the main importance of sound in discovering space and in proceeding through it; to be sure, it reminds one of the first perception of space the child has in the world of the mother’s womb.

Iegor Reznikoff, On primitive elements of musical meaning, section 2

The relation of the sound and space with a mother’s womb is indeed a symbolic one. The border relation itself, the relation between the inside and the outside seems to be perfectly embodied by the sound. Members of Indian tribes from the Great Lakes believed that places, where surfaces of rocks and water met, functioned as portals between the human and spiritual world and were particularly liable to be inhabited by ghosts (Manitius) 9. Echo, on the other hand, was an effect of shamans’ spirits moving through the cracks and fissures in rocks to the world of spirits and the other way around. In religious beliefs of Kawaiisu and Chemehuevi tribes, pictograms depicting figures were also called “rock babies” 10 because painted figures were supposed to present self-portraits of children’s souls whose sounds (echo) resembling crying could be heard from between the rocks. Owing to field research, the above mentioned sonic phenomena can be experienced at known sites such as Black Canyon or Creation Cave. An American researcher Steven Waller appears to seek conclusions similar to Reznikoff’s on the basis of the myth about the Yahawer – the Animal King. Rock paintings which, by shifting the sound, create atype of soundtracks simulating sounds of animals and figures presented on cave images, find their reflection in oral culture. Waller refers to examples drawn from over 500 similar archaeological sites all over the world characterised by similar acoustic qualities, where walls are covered with anthropomorphic and zoomorphic figures. It is worth recalling here a fragment of a story about Yahawer passed on by members of the Kawaiisu tribe – a resultant of several orally transmitted messages which have been synthesised.

This is a true story. Long ago there was a man (…). The man was sick or perhaps he just wanted luck in hunting […]. Nothing seemed to work so he then went to a place in Back Canyon (or another cave) and found the opening to the animal underworld, Yahwera’s home. At that hole, that goes down into the mountain, was a rock that opened and closed […]. The man waited and slipped through quickly. He saw many different animals—deer, bear, etc. These were animal-people who spoke just like the Kawaiisu. Near the mouth of the tunnel the man saw bows and arrows. These were the weapons by which deer were killed. The deer leave them when they go inside Yahwera’s house. He could hear rocks making the noise of deer. The man also saw the antlers of all the deer that have been killed. Yahwera said that the deer were not really dead. The deer that the man had heard all along the tunnel were the deer that had been “killed” […]. The man began to walk through the tunnel. He stumbled and climbed over a large gopher snake (kogo) that stretched across the tunnel serving as a door to Yahwera’s house. Farther along he came to a rattlesnake, as big as a log (tugu-baziit-b) and he climbed over it. Then there was a roaring brown bear (mo’orii-zhi) that he passed by and then he came to a grizzly bear (pogwit) that growled at him and went past it. Then he didn’t see any other animals. He heard a noise that sounded like a train. He kept walking and he saw Yahwera. Yahwera wore a mountain quail feather blanket. He looked like a hawk. Yahwera asked the man, ‘What do you want?’ The man said he was sick and wanted to get well. Yahwera knew all about his illness without being told. Yahwera gave him some acorn mush (alternatively pinyon or deer meat) […]. Yahwera asked him which of the songs he wanted and Yahwera named all the songs. The man took a song. The man was then ready to return home, so he kept going to the other end of the tunnel. […]. It is said that you hear him or her coming to you like quail, but it can also come with different animal voices.

Alan P. Garfinkel, Steven J. Waller, Sounds and Symbolism from the Netherworld: Acoustic Archaeology at the Animal Master’s Portal

Colladon´s lake experiments

Studying ancient approaches to echo and sound  propagation in general, it seems that the topic provokes a reflection beyond the divisions of states of matter: liquids, substances and gases, water and rocks, rocks and air. „e importance and meanings attributed to these “points of contact”, as we saw, had been sensed, practiced and used for thousands of years. What seems to be particularly interesting is the turn from practicing it to experimenting and theorizing the phenomena by modern science dealing with controlling sound in air. But not only in air.
In 1835, the Parisian Academy of Sciences announced a contest for measuring compressibility of basic liquids which was later to be won by Jean-Daniel Colladon, the Swiss scientist together with his colleague, mathematician Jacques François Sturm. They presented the results of their research on sound propagation in water – a piece which deserved 79 separate publications devoted to natural phenomena. However, what is most interesting to us is the effect of an experiment recounted in the following fragment of Colladon’s book “Souvenirs et mémoires”, in which he says without modesty, “I measured the speed of sound in water and showed that water is a liquid characterised by low compressibility.” Examining compressibility of water, i.e. its ability to change volume under the influence of atmospheric pressure changes, Colladon drew a conclusion that the most eficient way do to it is by conducting research on the speed of sound in water. He assumed that the speed of sound does not depend on frequency and wavelengths but density and the very compressibility of the system (in this case – water). Therefore, he decided to check the speed of sound propagating in water and conduct an experiment in situ at the Léman Lake in Switzerland as laboratory research he had worked on with Sturm had not brought expected arguments and at the same time, to their delight, the deadline of the contest they both entered was postponed. The experiment was repeated a few times but the main research was conducted on a November night in 1826 between Rolle and Thonon about 14 kilometres from the shore. The experiment required two boats – one was supposed to emit a signal, the other was to receive it. Colladon’s father sailed the #rst boat having on board a mechanism which involved striking the bell with a hammer and igniting gunpowder at the same time. On the other boat, Colladon measured time between the blasts with a chronometer, listening to the sound of the bell received by the system composed of an acoustic horn immersed in the water. The sound of the bell was received underwater owing to the bent cylindershaped pipe. Thee upper part of the pipe ended with a small hole located by Colladon’s ear. Eventually, Colladon’s experiment proved that in the temperature of 8°C, the sound moves with the speed of 1435 m/s. It is surprising how the result of this experiment corresponds with a theory on the same subject which preceded Colladon’s a few years. A French scholar, Pierre-Simon, marquis de Laplace, derived an equation to calculate sound speed in water on the basis of density and compressibility of the latter. The speed amounted to 1437 m/s – this result was confirmed in the later Colladon’s similar experiment in 1829 when
the calculation was done with the help of the theory of propagation of waves for liquids of slightly higher compressibility than water (1437,8 m/s). Fifteen years later, Colladon repeated the test of sound transmission on the Léman Lake in order to make sure that sounds can be transmitted at very long distances. He used a 500-kilogram bell from Lancy and built a larger acoustic horn. This time, the distance between the two boats equalled 50 kilometres. The test was successful but Colladon was convinced that the distance between the boats could have been doubled. What is more important, however, he predicted the benefits of the measurements for future generations, at the same
time sensing completely new sonic worlds, “[…] being used in deep seas, receiving sounds refracted from the sea bottom, in order to explore the depth […]” 11. The summary of Colladon’s experiments symbolise multi-directional conclusions drawn from the research on sound propagation. Sound in space becomes a tool; it allows space to be measured. Discovering the speed of sound propagation in water and the fact that ultrasounds, similarly to light, are transmitted in the form of waves, led to the launch of ultrasonography and development
of medicine. Knowledge of the rules and conditions enabling sound travels was also of signifcance to the application of this mechanism to measure space, including systems of acoustic mapping of space. In this type of the system, localisation of the sound source is usually based on the geometrical simpli#cation of the assumption behind sound propagation in space in order to create a map of a given territory. „e sound was often much more effective than light, for instance due to fogs making even a strong beam of light projected from the lighthouse useless to sailors. No surprise that new research directions were launched – in the search of signalisation other than the one using light, the one which would be effective enough to be able to warn and direct sailors before they cross the safe distance from the shore but also to warn employees of the railway about dangers along the traction. On the other hand, we know that the horns had been used for signalling for hundreds of years as well as simple bells or manually struck gongs and whistles. At times, cannon shots were also used to warn ships. In 1819, baron Charles Cagniard de la Tour presented a device with “features of an alarm siren” 12. It served as a test device for measuring frequencies and it found practical application as a warning signal on ships and perhaps this is the reason that de la Tour is often credited with being the inventor of the siren which is obviously not true. In 1820, the siren was patented as a new acoustic instrument which “is heard in water due to its sonic qualities”, taking its name from mythological sirens. Etymology of the word “siren” comes from the French term “sereine” and it tended to be confused in literature with mythological sirens, i.e. these who sing sweetly or beautiful creatures who enchant and seduce men 13. It was also praised for its &awless sound in encyclopaedias of mechanics. Prototypes were propelled manually by a crank mechanism which gave it a characteristic rising or falling glissando. Even small versions of this device were able to generate sounds of high volume but, despite elimination of the element of putting it into operation manually, it kept the uniformly developing tone which continued to signal danger. In most signalling horns, a vibrating stream of air is used to produce sound. James William Newton claimed that he invented a signalling technique based on loud and low sound. It is Robert Foulis, however, who is considered to be the creator of the #rst automated steam-powered signalling horn. He came up with the idea when he heard his daughter play the piano on a foggy night. He then realised that in those conditions lower tones are audible unlike the higher ones – which is due to their omnidirectionality. Soon he constructed a device which produced low sounds. In 1859, his signalling system was installed on the Partridge Island, but Foulis spent the majority of his life claiming his rights to the invention in court. In the meantime, another researcher Celadon Leeds Daboll built a coal-powered signalling horn which got installed in a few lighthouses.

Tyndall´s sea shore symphony

Perhaps the most comprehensive was an interest in signalling horns of John Tyndall and baron John William Strutt Rayleigh. Together they created a project of a gigantic signalling horn which could obtain the furthest reach of sound, at that time of course. The project shattered
faith in sound as reaching places light could not reach – of course due to various phenomena influencing the sound’s movement in air to which Tyndall dedicated an entire treatise. Already in 1708, William Derham wrote about the factors conditioning the sound intensity in the atmosphere. He discovered that fogs and precipitation, especially snow, heavily impede transmission of sound, whereas e.g. freezing does not have such an effect. This result was challenged for about 50 years by Pierre Jean Édouard Desor but only to find confirmation in experiments conducted by John Tyndall in 1874. The latter took part in a project aiming at increasing eficiency of signalling horns and within this project, he established that the sound is partially refracted in the moment of the contact of air masses of different temperature, and more precisely, when atmosphere contains two or more separate air masses. Tyndall discovered that phenomena such as fog or rain do not have much inffuence on weakening of the sound signal at least as far as the range of frequencies of transmitting appliances used in his experiment were concerned. This does not mean, however, that the sound propagates in air as if it was nothing. Let us look closely at one of the experiments conducted by Tyndall which could be just as well understood as an outdoor concert for sirens, gunshots, water and air. A few steam-powered signalling horns and cannons directed towards the sea were placed around 70 metres above sea level, on the cli% near Dover, England. On May 19, 1873, the main experiment was conducted with the use of the following devices placed on the cliff: two 11-feetlong brass horns, a 6 inch diameter whistle, a 12 inch diameter steam whistle connected to the steam boiler. At the foot of the cliff, there were two other horns of the same size and arranged as the ones above them and a 6 inch diameter whistle. At that time, the maximal distance travelled by sound  qualled 5,63 km (= 3,5 miles). But Tyndall noticed that there was a strong wind and the sea was rough producing additional sounds typical of open space which affected the assessment of sounds reception and sounds themselves. On the other hand, “calm water transmits the sound with amazing purity and strength”, Tyndall quoted Sir John Hershel in his notes from the conducted experiments 14. They had place several times in different weather conditions. Tyndall described his observations on various kinds of “acoustic clouds” 15 diversed by the degree of humidity and temperature. According to him, the intercepted sound is weakened by repetitive refractions which then become audible. He attributed the observed oscillations in sound transmission to the movement of the mentioned “acoustic cloud”.

Up to the present time all signal-sounds have been made in air, though this medium has grave disadvantages: its own currents interfere with the sound-waves, so that a gun or bell which is heard several miles down the wind is inaudible more than a few furlongs up it. A still greater evil is that it is least effective when most needed; for fog is a powerful damper of sound. (…). Prior to this investigation the views here enunciated were those universally entertained. That sound is unable to penetrate fogs was taken to be “a matter of common observation.” The bells and horns of ships were affirmed “not to be heard so far in fogs as in clear weather.

John Tyndall, The Atmosphere in Relation to Fog-Signaling

Moreover, Tyndall observed echo which returned to its source with nearly the same intensity with which the sound was emitted, assuming the sky was clear. But in the case of siren sound, it was strengthened through evoking additionally its own echo during the course of sound movement (due to its uniform development), and on top of that the transmitted signal returned in a changed form as a completely new sound.

The „centre” and crossing the boundaries

Tyndall’s report not only covered his systematic research on sound propagation above the ocean, but it also analysed everyday observations concerning the effects of sound transmission including various receptions of the sound of bells in the open space. Other archival resources, similarly to the earlier mentioned archaeoacoustic research, might also be the source of information on the social aspects of sound. Bells – used by both Colladon and Tyndall – turn out to provide unusually extensive information about the relation between sound propagation and social organisation of space – the former being accomplished somewhat via the sound. „is approach was developed in 1998 by Alain Corbin who took up theoretical reflection over the soundscape of the 19th-century French countryside in the context of mutually affecting each other: natural environment and the way this environment is perceived, on the example of the sound of bells creating “the feeling of being rooted in [social] space”16

Through bells an individual was better able to apprehend the identity of a group to which he belonged. They helped him locate himself in space and time. They audibly proclaimed to him the order of the society within which his life unfolded, and made manifest the power of the constituted authorities. Yet this was not the whole story; in the countryside bells were the most important medium of communication, and their history is chiefly concerned with this fact.

Alain Corbin, Identity, Bells and the Nineteenth-Century French Village, pp. 200

The e key function of the bell was to raise alert in case of approaching danger and to inform about events crucial to a given society. Then, one can trace a specific correlation between the bell, the very process of transmitting the sound and the people who could distinguish types of delivered information depending on a situation and adjust to provided instructions. Therefore, the subjects could identify ringing which indicated the flow of time (literally standing for today’s watches), or announcing events important to a given territory’s inhabitants, for instance the arrival of a sovereign or other officials. Thee sound of bells helped establish territorial identification of people living in its range. Bells – heard from contemporary administration centres – marked the boundaries of their jurisdiction through symbolic constitution of the area where they were audible, at the same time creating a specific social sonic community whose axis mundi, naturally, was a bell tower, most often located by a church or other similar sacred building. The bell could also intensify territorial divisions by marking a limited structured zone by means of sounds emanating from the centre. L’ esprit du clocher clearly pointed out territories within the range of the bell sound and these outside of the range of its audibility, showing the community several signs of its affiliation to a given administration and informing about events important to members of a given district. Another interrelation emerged between the loudness of the bell and the size of a territory of a given administrative centre. It was important to guarantee that none part of the territory remained without the access to the sound of the bell and consequently, was deaf to public announcements, alerts or orders. And, to avoid omitting any areas where messages could be misinterpreted or di’cult to receive. Archives, mainly in the secular context, provide many examples of complaints regarding inaudibility of the bell on a certain territory which should be within its range. Clergymen reserved striking the main bell only to call the subjects for assemblies. In 1590, the board of Toulouse district released a decree forbidding bell ringing in country churches without an earlier sound signal from a cathedral or “a mother-church”. However, the community sometimes demanded to be allowed to use the main bell also in other situations than the religious ones, for instance in case of danger or bad weather. We have no knowledge of similar acts from the Middle Ages but such legal settlements must have taken place.
In opposition to the cases earlier analysed on the grounds of the research conducted by archaeoacoustics, church bells had an entirely different proxemics. The key element was not to blur sound sources but to underline and centralise them. Spherical sound propagation corresponded to the administrative and juridical organisation of villages as described by Corbin. The very elevation of bell towers is a gesture of being lifted above possible refraction from architecture and landform. It prevented the sound from being detected but, as naturally as possible, it reverberated over broad pieces of land. Similarly to archaeoacousticians’ findings, however, the material is not to be overestimated here. As the sound range is the most crucial aspect, increasing it is a function of rarity of materials used to build the bell – the louder the bell, the larger and more extensive authority of a given centre. Early bells were not only sizeable bronze objects installed in towers to give a strongly resonating sound which was carried at long distances and, what is important, did not make the bell-ringer deaf17, but also smaller ones used in everyday activities. Thee former were easier to manufacture but when hung in the farmyard or on animals’ necks, they still had great efficiency of producing a considerable acoustic field. Materials used for casting bells are of great significance for yet another reason. In the Middle Ages, air was often ascribed special qualities with regards to demons inhabiting it, who were responsible for spreading diseases, plagues, frost and weather anomalies. From this point of view, wonderful qualities of bronze from which bells were made brought relief in parallel to the sound. Their sound was even identified with the voice of God – “When your voice resounds, no harm can be done to anyone”, as the inscription on the bell in Montain (Tarn-et-Garonne) informed. In the Middle Ages, bells were sometimes considered to be the central element of Christian religious practices, especially in the context of the conflict with Islam.

Bells played a key role in the medieval shaping of the Christian identity. The 1216 bull of Pope Innocent III directed to the Maronite Church in Lebanon mainly contains a concisely formulated rules and practices of Catholicism concerning, among others, the character of the Holy Trinity, christening and other sacraments but also information on the importance and nobleness of the sound of bells (campanas) which “should indicate hours but also call the faithful to the temple”18. Drawing from archaeological material and written resources, John Arnold and Caroline Goodson state in their article that the history and meaning of church bells is more complicated than it is often assumed. „e bell calling people to prayer was then not only an indication of time but also an appeal for the spiritual community and so its voice could be contested from time to time. Some scholars believe that the usage of bells dates back to the late ancient period and they also noticed the conjunction of bells, liturgy and community. There is evidence confirming that in the 7th century, bells were mainly used in monasteries around Europe, e.g. to indicate hours of the liturgical life of the community and deaths of its members. „e medieval times provided proofs on applying also other signalling mechanisms in the context of church and liturgy, but also in the secular one. When Romans wanted to summon the army or announce something (signa/signum), they performed it by using horns which remained in use outside church practices. The use of trumpets and horns can also be found in the Old Testament and in the 4th-century Rule written by Saint Pachomius, the Egypian monk, in which he states that these instruments delivered strong and resonant signals to call up the faithful.

In this perspective, it is worth paying attention to the 9th-century resources describing the cultural con&ict initiated due to the use of bells in Christian communities and muezzin calls to prayer (adhan) performed five times a day. It could be read as hostility towards the summoning function of church bells but it is good to remember that Islamic adhan, apart from its signalling role, also serves propagating the faith. It might seem that the sound of bells – for Muslims – carried similar, therefore unwanted, information. Bells gave consent to the voice of Christianity, and transmitted sound waves worked not only as a marker of time but as manifestation of Christian faith in a given space. In the 9th century Saint Eulogius of Córdoba described reactions of Muslims to the sound of bells, “As soon as they hear the sound of clanging metal in their ears, as if beguiled by a false superstition, they begin to exercise their tongues in all kinds of swearing and foulness”19. Muslim public prayers and criticism of Christian bells were presented alike by Paul Albar of Córdoba (the 9th century). He recalls that each night they cursed the Lord and at the same time worshipped their prophet. On the contrary, Christians such as Albar noticed analogical functions of adhan and bells calling to prayers. Nevertheless, they still perceived Islamic practices in a pejorative manner. Albar claimed that muezzin calls “taint the souls of noble people”20, while Saint Eulogius recalled his grandfather attempting to cover his ears from muezzins’ cries.
Already in the Middle Ages, apart from “occupying space”, bells also had functions described by Tyndall in the context of his anticipation of constructing sonars: they “measured space”. Bells also served as navigation devices for travellers to be able to recognise space in which they were heard and to signal their presence. „is particularly concerned hilly and wooded lands and, as in the case of lost sailors, coastal areas. In unfavourable weather conditions, the sound of bells was carried through storms, fogs and gales replacing lighthouses. In the mountains of the Auvergne region, bells were heard from 5 to 6 o’clock and until 11 pm when the land was covered with snow in order to help stray travellers #nd their position towards the monastery  which was superior to parish churches of lower rank. At times, bells in the mountains were forbidden due to the risk of causing avalanches. Bells also happened not to be allowed during storms because lightening started to be associated with cases of bell-ringers being thunderstruck, even though still in 1838, François Arago wrote in his “L’Annuaire du buremu des Longitudes” that “owing to the current state of knowledge, it cannot be ascertained that the sound of bells strengthens the power of thunders, or that any other loud sound causes their claps”. 21
In view of widespread globalisation, as a result of the sudden increase of introducing omnipresent telecommunication systems, many areas of the contemporary world strive for keeping old traditions, including the whistling language. It is worth mentioning in this context of calling and travels of sound. It enables free transmission of information understood as the exchange of potentially unlimited sets of messages at much longer distances than human speech, even up to 5 kilometres. It was found in hardly accessible mountain areas of low and often dispersed population where everyday communication is very difficult which is sometimes related to traditional professions characterized by temporal seclusion and isolation such as being a shepherd or a farmer growing crops on hillsides. Cases of using the whistling language are also known in areas of dense woods such as the Amazon river basin where it replaces speech during hunting or fishing – this helps receive the sound among the overwhelming natural acoustics of the surroundings. Additionally, these languages are also used in the case of inability to communicate via “normal” speech, e.g. at night, due to better transmission of high pitch tones present in whistling than of medium frequencies used in usual communication. Whistling languages differ from other types of whistled communication as they code aural functions taken from spoken languages through transposition of key elements of speech sounds. But, at the same time, they are complementary to the local language because, in order to use this language, it is required to apply syntax, vocabulary and grammar as used in speech. According to people who use this language, whistling is one of the types of its sounds next to whispering, screaming and singing.
The ways of using the attained knowledge in the field of acoustic propagation seems to be countless in the face of contemporary development of recording and sound generating techniques. However, in order to understand various historical sonorities and follow the archaic journey around the knowledge of new music, people searching for avantgarde sounds should be sensitive to resonances happening in the archives and remain open to all kinds of resources.

  1. On the basis of the conviction that compression of impulses generated by sound does not change temperature, he derived the equation based on Boyle’s law: v = √T/u ↩

  2. http://www.landscape-perception.com/archaeoacoustics/ ↩

  3. Ibidem ↩

  4. http://www.monumental.uk.com/site/research/proj/acoustics/dwarfie.html ↩

  5. David Whitwell, Essays on the
    Origins of Western Music,http://whitwellessays.com ↩

  6. http://www.landscape-perception.com/archaeoacoustics/ ↩

  7. Ibidem ↩

  8. Iegor Reznikoff, Sound resonance
    in prehistoric times: A study of
    Paeolithic painted caves and rocks,
    http://www.researchgate.net/publication/
    5325208_Sound_resonance_in_
    prehistoric_times_A_study_of_Paleolithic_
    painted_caves_and_rocks ↩

  9. Alan P. Garfinkel, Steven J. Waller,
    Sounds and Symbolism from the
    Netherworld: Acoustic Archaeology
    at the Animal Master’s Portal;
    http://www.petroglyphs.us/Article_
    Sounds%20and%20Symbolism%20
    from%20the%20Netherworld.pdf ↩

  10. Ibidem ↩

  11. Jean Daniel Colladon savant et
    industriel genevois, http://www.villege.
    ch/mhs/pdf/aide_colladon.pdf ↩

  12. Anthony Burr, Charles Curtis, Physics
    and metaphysics of sound, http://
    www.gardenvariety.org/projects/
    lucier/booklet.html ↩

  13. Ibidem ↩

  14. John Tyndall, “The Atmosphere in
    Relation to Fog-Signaling”, Popular
    Science Monthly, Volume 6, March
    1875, http://en.wikisource.org/wiki/
    Popular_Science_Monthly/Volume_6/
    March_1875/The_Atmosphere_in_Relation_
    to_Fog-Signaling_I ↩

  15. Ibidem. ↩

  16. Alain Corbin, Identity, Bells and the Nineteenth-Century French Village, in. Village Bells: Sound and Meaning in the Nineteenth-Century French Countryside, Columbia University Press, New York, 1998, pp. 95. ↩

  17. Piotr Wiecławski, Analiza dźwięku dzwonu Tuba Dei, UMK, 2002: 43, http://www.fizyka.umk.pl/~przeciu/analiza.pdf ↩

  18. Ibidem ↩

  19. Ibidem ↩

  20. Ibidem ↩

  21. Ibidem ↩