Some recent sound artists have explored infrasound, or sound waves with a frequency too low to be detected by human hearing. Scientists first became aware of infrasound during major seismic events, but many of them now theorize that it occurs many other places in nature. In order to make infrasound audible, it needs to be sped up or otherwise transformed. With the advent of digital sound technology, it is possible to transform virtually any kind of data into sound. For example, several composers have used fractals, neural networks, cellular automata, and genetic algorithms to generate music, all of which are a natural application of digital synthesis.
Recently I've been listening to John Duncan's 2003 release Infrasound — Tidal, which uses sound sources from Australian sound researcher Densil Cabrera. The album contains a single track, but with a number of divisions for tidal, seismic, and barometric data. It's easy to understand Duncan's fascination with the material. The tidal section is a near constant pitch, but with a rich set of overtones and placements in the stereo field. It compresses nearly 300 years of tidal data into just under twelve minutes. The seismic section sounds mostly like white noise, with some occasional ripples like the runoff area of a vinyl record along with some ghostly little chirps and booms. The longest portion of the recording, the seismic data covers about a month, with some of the sonic events mapped to earthquakes and nuclear tests from the Pacific basin. The final section, based on 48 years of barometric data, again is centered around a constant pitch, but is a much bigger sound, with an undulation like ocean waves moving across the stereo field in the background.
The album fits comfortably in Duncan's discography, which in recent years has moved away from his early noise releases to an investigation of different kinds of drones, as well as finding music in a variety of non-musical sound sources (his album Palace of Mind, for example, uses unspecified "data files" as a sound source). It's unclear to me exactly how the data was transformed into sound, but Cabrera, who created the original sound files which Duncan used as sources, is a sound artist in his own right. His web site includes a hidden page that documents a number of his installations, including tantalizingly brief snippets of the raw sound sources that went into Duncan's release.
Of course, Duncan and Cabrera aren't the first sound artists to use infrasound. One of the other interesting ones is Felix Hess, a Dutch physicist and artist. Hess created a number of small devices sensitive to air pressure fluctuations (another application of infrasound). He developed microphones that could record these fluctuations, then ran a tape recorder outside for five days, with the microphones places 64 meters apart, then sped up the recording to 360 times its original speed, compressing five days into twenty minutes. The results sound vaguely similar to Duncan and Cabrera's seismic data, albeit with a great deal more detail. His recording of Air Pressure Fluctuations was released both as a standalone CD and included in a book about his work.
In the Infrasound — Tidal liner notes, Duncan describes how he met Cabrera on the net and Cabrera provides more technical notes about the pieces. Duncan, perhaps somewhat disingenuously, professes interest in the work simply as sound, rather than for whatever value there might be in the scientific data, and claims to have destroyed the inherent linearity of the data (a claim not entirely commensurate with Cabrera's notes, which include specific events for the seismic portion of the recording). For despite the similarities between this music and other instrumental music, there remains a basic non-intentionality here that would not be present in more composed music. John Cage made a career out of composing without his ego getting in the way, and there is a similar impulse at work here (even if the sonic results are completely different). Listening to this music opens up new levels of perception, an awareness of the timeless patterns of the earth that continuously surround us, to which we ordinarily remain oblivious.
In addition, infrasound music operates at yet another timescale beyond the normal linear perspectives where music typically operates. Rather than simply seeking to evoke a feeling of timelessness like most drone music, these infrasound recordings work on a concrete timescale that is simply larger than humans can comprehend. The intent is the opposite from efforts to take relatively short pieces and expand them to the limits of comprehensibility. The best known example is probably Leif Inge's expansion of Beethoven's Ninth Symphony to fill a 24-hour period, 9 Beet Stretch, but the topper here is the John Cage Organ Project, which presents a relatively short keyboard composition entitled ASLSP (As SLow aS Possible) over a period of 639 years. The music from Duncan, Cabrera and Hess takes a natural process that spans a long period of time and compresses it into a human timeframe, and thereby evokes the mystery and majesty of our planet's geological rhythms.