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[qualia]

Rainwire Project Background

A central environmental and climatic problem of 21st Century science is the protection of freshwater resources. Availability of freshwater for human consumption, agriculture and industry is both a national and international concern. The foremost source of freshwater is rainfall, and underground water sources are also ultimately dependant on this same source. The complex problem of understanding natural rainfall events is vital for informed sustainable land management, and fundamental research in complex systems, climatology and meteorology. The project will deliver national benefit by positioning Australia at the forefront of environmental sonification by demonstrating fundamentally different and novel approaches for land based rainfall research. Key algorithms will be developed for extracting the sound signatures of different rainfall patterns from induced vibrations on long wire spans. Human listeners are capable of identifying rainfall patterns acoustically with long wire sonification. As with face recognition by computer, many years of research will be required to match human faculties with machine algorithms. There is therefore great potential for future research into this aspect.

The Rainwire project will be a significant advance for an important area of non-linear vibration research in long wire physics. The long wire span is a suspended cable, a key complex dynamical system with applications in many fields of engineering (mechanical, civil, electrical, ocean and space). Suspended cables have significant research interest, in particular the investigation with stochastic / random excitation and rain-wind induced vibration, is a vital area where new studies and results are important (Rega 2004b, Ibrahim 2004).

Rainfall event properties are key requirements for research in environmental processes (e.g. canopy interception, flooding, soil erosion, run-off, overland flow, ponding), agricultural processes (e.g. wash-off of agrochemicals on plant foliage, water use efficiency, geochemical and nutrient balance), flood management, rainfall simulation and modelling, built environment and urban drainage. Research in understanding and detecting global and regional environmental change require these rain event properties to be analysed at the sub-daily level. Such high resolution rain event properties have even greater importance given the likelihood of an increase in extreme rainfall events and associated requirements for adaptive management.

Rainwire has the potential to provide new weather / climate based products and information services, potentially available in real time over the internet or through mobile devices. Information use would be “smarter” through improved rainfall data for agriculture, with potential for use in a number of other industries. A longer term future application is in general problems of irrigation. Gardens, parks, sports fields etc. are commonly seen being sprinkled immediately after heavy rainfall, sometimes during rain itself. The virtue of this technology is that it can be extended to operate across any wire fences. This in turn, with the increasing availability and decreasing cost of digital signal processing chips and wireless computer communications, makes it possible to move to much more controlled irrigation, saving precious water supplies.

The Rainwire project will have wide national and international significance due to its foundation in the field of complex systems research, which coupled with the unique approach of integrating rainfall sonification, represents the cutting edge of multidisciplinary scientific research. Better models of complex systems coupled with new mathematical and algorithmic tools, will eventually lead to benefits in human health, national security, economic well-being and sustainability.

Acoustic investigation of rainfall on land has been minimally investigated (Michaelides 2008). This stems from an inherent problem with designing acoustic sensors to cover a wide spatial area. Researchers have recently attempted to directly transfer underwater acoustic methods of rainfall analysis to small water tanks of <50cm2, but much more work is needed due to problems such as high maintenance requirements, tank freezing and difficulties with bubble noise in the small tank chamber (Winder and Paulson 2010). Current vibrating wire instruments for rainfall measurement are expensive and cover a very small (<1m2) geographic area (Duchon 2008), and as such are impractical for use on farming properties by land managers or for other key rainfall event properties. Other sensors such as optical disdrometers/distrometers and vibration based droplet spectrometers suffer from similar problems of expense and very small spatial area coverage (Michaelides 2008). The limitations for new sensors are imposed by a lack of signal processing methods, rather than technological or even cost issues.

Methods of sonification of environmental data for scientific application to date have been based on digital sound generation from data, as opposed to analogue means. In these projects the phenomena under examination have been sampled to create data sets that are subsequently ‘mapped’ in an arbitrary way to sound synthesis engine parameters that produce audio output (Childs & Pulkki, 2003). However, the more the data is mediated, the less direct the relationships are between the stimuli and responses. The resultant audio in typical sonification projects bears an arbitrary relationship to the source phenomena because the process is abstracted through the creation of a data set.

Rainwire will contribute to the complex systems research knowledge base in the following key areas:

i) extending the scope and methodology of acoustic rainfall detection, classification and quantification from its present use in underwater systems to a land based system. This will be enabled through the application of signal processing, and new/existing complexity measures.

ii) extending knowledge in the non-linear dynamics of random excitation and fluid interactions with suspended cables

iii) publically available datasets of high resolution long wire instrument rainfall sonifications for explorations of physical theory and pattern recognition.

Acoustic analysis using Digital Signal Processing (DSP) techniques have been successfully applied to high resolution rainfall measurement and analysis at sea using underwater acoustics for decades. Initial research was conducted during World War II when rainfall was discovered to impact on military sonar. Techniques were subsequently developed for Acoustic Rain Gauges (ARG) to identify rainfall events through unique frequency spectrum characteristics between 1 and 50kHz (Black et al 1997, Amitai and Nystuen 2008). The unique characteristics of rainfall impacting water are created by the initial impact and the subsequent formation of an underwater bubble for certain raindrop sizes. These variable drop impacts produce different frequency signatures as a result of this unique mechanism, which can be used to deduce important rainfall parameters. Rainfall sounds are recorded by hydrophones attached to ocean buoys from a depth of tens or hundred of metres, with the most recent experiments at depths of 2km. The listening radius for these underwater ARG’s is nearly three times their depth, giving a very wide spatial listening area. The development of ARG’s was initiated by the difficulties of deploying standard rain gauges on the ocean surface. However, because they are isolated out at sea for very long periods, continuous recording is not possible because they need to conserve power. ARG’s spend much of their time simply checking if rainfall is present at the surface at specified intervals and can miss out on the beginning of a rainfall event. ARG’s are capable of high temporal resolution recordings of rainfall data due to the acoustic nature of the information recorded.

Sonification is the presentation of data or information via sound, and the most well known scientific instruments in this field are the Geiger counter and Sonar (Kramer 1994, Hermann 2008). Long wire instruments fundamentally differ from existing data based sonification processes and rainfall measurement devices by generating sonic events directly from rainfall patterns in realtime. Sonfication from real world physical actions, as opposed to being mediated via electronic sound synthesis mapping, can be seen in an early example by Galileo Galilei in the formation of the law of falling bodies (Plessas et al 2007). In this experiment Galileo attached bells to an inclined plane in order to make his discovery.

Long wire instruments are made from standard high tensile fencing wire constructed in single or multiple spans across an area of the landscape. Piezoceramic transducers are used to convert mechanical vibrations caused by rainfall events into audio signals for measurement and analysis, effectively sonifying the rainfall patterns. Long wire instrument spans can range from tens to hundreds of metres, up to a total multispan length of several kilometres or more, usually supported by poles or attached to very large rocks. Spatial arrangements can typically be in the form of a single line, parallel lines, radial lines from a central point to compass points (e.g. NESW) or other geometric shapes. Long wire instruments can be constructed on flat land, across gulley’s, down hillsides, over complex terrain and sections of water.

Long wire spans are classed as suspended cables, which exhibit a complex variety of non-linear dynamical behaviours, and are an archetypal complex system of interest (Ibrahim 2004, Rega 2004a, . Complex systems is an emerging multidisciplinary science developing new ways of researching large, highly intricate, dynamical systems in diverse areas such as biology, physics, social networks, socio-technological systems, socio-ecological systems, economics and the environment (Mitchell 2009, Norberg & Cumming 2008).

Demo Soundfiles

Rainwire is conceptually innovative in that the field of scientific data sonification has emerged very recently. However, unlike most existing sonification systems where sound/music is attached to waveforms, in our project the sonification is intrinsic. The conceptual innovation now lies in identifying distinctive sound patterns and relating them to particular types of rainfall event.


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[pete34]

plant trees if you want rain

trees pump water into the sky

trees seed the clouds with microscopic organic matter

making rain just takes it from where it naturally wants to fall

[qualia]

do you know what the word sonification means?

[Halcyon Daze]

Sounds like millions of laser beams. Sounds mad