Information on the individual sound phenomena
• Volcanoes and geysers
The volcano recordings were made at
Mt. Yasur in Vanuatu (one of the world’s most active publicly accessible volcanoes), at Vulcano Arenal in Costa Rica, and at Mount Etna in Sicily. The geyser sounds are from Iceland and were kindly made available by Hanna Hartman. In
fire pattern, these natural sources were combined with man-made sounds, two of which are briefly described below.
• Singing flames
The phenomenon of singing flames was discovered in 1870 by Frédéric Kastner and used in his “pyrophone”. This “fire organ” consisted of glass tubes, in each of which a gas flame causes the air column to vibrate. Depending on the length and diameter of the tubes, each singing flame could be tuned to a note. Kastner’s invention was soon forgotten, as the town gas in use at the time soon proved too unsafe and toxic. Today, the singing flame principle is used by sound artists including Andreas Oldörp in sound installations. Different gases such as hydrogen, propane, butane and methane are used, which possess different light and sound properties and which can be adjusted to the requirements of each project. The recordings of singing flames used in fire pattern were made in
Andreas Oldörp’s workshop. They were supplemented by recordings of the “chemo-acoustic” instruments of the performance artist Bastiaan Maris who uses gas flames to play huge metal pipes.
• Ignition of burning alcohol in a bottle
This effect, known as the
whoosh bottle, is often used in physics lessons to demonstrate processes of combustion. For fire pattern, several large glass flasks were rinsed out with pure alcohol and ignited at the opening. This creates a mounting sequence of puffs of varying lengths that resonate with the various frequencies of the bottle. The resulting sounds are reminiscent of those made by volcanic eruptions and geysers.
• Singing icebergs
On July 22, 2000, in the Antarctic a huge iceberg measuring 25 by 15 kilometres struck a rocky protrusion on the sea bed. Over the following 16 hours, the iceberg scraped over the sea bed, triggering a local earthquake. The seismic data were recorded and analyzed by the Alfred Wegener Institute’s Neumeyer Research Station and by the company of Fielax. It was possible to transpose the infrasound signals into the audible range, resulting in sustained, screeching sounds with slightly varying tone. Water is probably forced through cracks and hollows within the ice at high pressure, causing the walls to oscillate. The researchers coined the term “singing icebergs” and published their findings in the journal "
Science" (Vol. 310, p. 1299). Significantly, the sounds from the iceberg resemble the
tremors recorded prior to the eruption of volcanoes. This has raised hopes of being able to gain new insights and facilitate predictions concerning volcanic tremors, as icebergs are far easier to study than volcanoes.
• Dispersion of sound waves in ice sheets
The sound recordings of frozen lakes were made in the winter of 2005/06 in the area around Berlin. Frozen lakes are known to give off most noise during major fluctuations in temperature: the ice expands or contracts, and the resulting tension in the ice causes cracks to appear. Due to the changes in temperature, the hours of morning and evening are usually the best times to hear these sounds. In my experience, thin ice is especially interesting for acoustic phenomena; it is more elastic and sounds are propagated better across the surface. Snowfall, on the other hand, has a muffling effect and the sound can only travel to a limited extent. The ice sheet acts as a huge membrane across which the cracking and popping sounds spread. Underwater microphones proved especially well-suited for these recordings: in a small hole drilled close beneath the surface of the water, the sounds emitted by the body of ice carry particularly well. The most striking thing about these recordings is the synthetic-sounding descending tones caused by the phenomenon of the
dispersion of sound waves. The high frequencies of the popping and cracking noises are transmitted faster by the ice than the deeper frequencies, which reach the listener with a time lag as glissandi sinking to almost bottomless depths.
• Ice sizzle
Glacial ice consists of snow that has been extremely compressed and compacted. In the case of the inland ice in Greenland, this process may stretch over thousands or even millions of years before the ice is pushed into the sea by a glacier. As the layers of snow pile up, tiny bubbles of air are trapped and put under enormous pressure by the weight of the surrounding ice. When the glacial ice finally melts in the sea, these tiny bubbles of air are released with a quiet, explosive popping noise, adding up to a many-voiced
sizzling. The icebergs that drift in the Arctic give off a constant sizzling sound which is loud enough to determine their position from under water. The phenomenon was first noted by the crews of submarines. It is also known as “bergy seltzer” due to its resemblance to the sound of fizzy drinks.
• Snow on aluminium foil
It is extremely difficult, nearly impossible, to get a decent recording of falling snow because the signals would always be too quiet. This problem can be solved by using aluminium foil stretched on a frame and a contact microphone. The foil acts as a microphone membrane onto which the snowflakes fall directly, allowing them to be recorded. There are many different kinds of snow – the wetter and heavier the snow, the heavier it falls, the harder the sound, eventually sounding more like rain. The most interesting sounds are made by light and fluffy snowflakes in which snow crystals cluster together. These snowflakes thaw on impact and give off fine crackling sounds.
• Creaking and cracking ice
Members of 19th-century expeditions to the North Pole who were trapped in the pack ice and forced to spend the winter there told of the creaking, screeching and booming sounds that came from the constantly shifting ice, to the profound consternation of the sailors (an excellent account can be found in “The Terrors of Ice and Darkness” by Christoph Ransmayr). When two mighty ice floes are pushed into or over one another, the friction between the edges can produce very loud squeaking noises, distantly resembling those of scraping metal and the like. But this phenomenon can also be experienced in a less spectacular context, for example by pressing lightly on the thin covering of ice on a freshly frozen pond or puddle. This will usually produce a fine squeaking sound and the ice will crack under the pressure being exerted on its surface.
I am grateful to the following for their kind support: Alfred Wegener Institute in Bremerhaven, the company of Fielax, Hanna Hartman, Kain Karawahn, Bastiaan Maris and Andreas Oldörp.
Translated by Nicholas Grindell