Infrasound Research

Normative audio microphone and recording devices are explicitly designed to exclude infrasound. This project aims to develop a custom-made mobile infrasound (air vibrations lower than 20 Hz) monitoring and recording device. Infrasound is a continually active bandwidth of air fluctuations. Its a realm of colossal acoustic waves – some well over 100 Km in length – that at times circumnavigate the globe. Infrasound is the realm of geological vibrations of earth movements, volcanic eruptions, ocean surface oscillations and aurora borealis. Its also the realm of large mammal communication like elephants and wolves. Its also the bandwidth of the anthropocene pervasive human signatures have begun saturating the spectrum: activities such as container shipping, mine explosions, space debris re-entry (almost daily), aircraft sonic booms, wind turbines, oil refinery gas flares and nuclear detonation testing are part of the contemporary infrasound signature. Infrasound monitoring is generally restricted to scientific and military applications and often involves stationary monitoring stations and costly specialized sensors. This projects aims to make infrasound accessible in a portable handheld device, allowing remote and mobile monitoring of infrasound fields. Additionally, the project hopes to develop practical methods for raw signal transduction and storage that can interface with a variety of audio-visual and data extraction methods. The intention is to provide a practical method for infrasound signal acquisition that can also be thought of as a prototype for other non-standard environmental sensing applications. As such the infrasound sensor / recorder hopes to provide a preliminary model for other citizen based monitoring and culturally oriented transduction projects. Its important to note this project is interested in aqualitative diversity and poetic precision (rather than numerical accuracy) of infrasound reception. In particular the manners in which infrasound's spatial-material agency becomes tangible through processes of monitoring and recording. As such the unit is conceived as a tool for testing infrasound agency within broader cultural, social and geological circuits.

Research Questions

1. What practical functions and attributes should an exploratory infrasound-sensing device include?
2. What are the spatial-material qualities of infrasound accessed by way of mobile signal acquisition?
3. How do non-standard sensing tools open up alternative portals onto the environment?
4. Conversely, how does the sensing of imperceptible environmental fluctuations effect notions of subjectivity and surroundings?
5. How do tools reconfigure when they are conceived at the intersection of geological and sentient agency?

The Unit

INFR_SNSR is an environmental infrasound sensor and recorder. The unit is a handheld, battery- operated device, for infrasound signal acquisition. It incorporating custom-made infrasound sampling hardware coupled with geolocation (dynamic gps tracking) and onboard recording all optimized for extended mobile use.

Signal Monitoring

The unit includes infrasound signal (and data) recording on removable microSD card as well as auxiliary digital signal output (for real-time remote sensing and PC monitoring), control voltage output (for patching to modular electronic devices) and real-time audio signal output (for headphone monitoring and audio applications).

The Code

The unit is driven by a microcontroller with code developed from scratch for non-standard mobile signal acquisition and monitoring. A custom RIFF (audio / visual digital file container) file header has been developed (SNSR) as a general container for non-standard transduction data storage. The header tag in the RIFF of this unit is INFR, designating infrasound files. The aim is to develop a general file format that can be implemented in other custom-defined sensors as well. Raw signals recorded on microSD in the SNSR format can then be passed through various interpolation methods and other data extraction methods on a standalone PC program via a simple GUI interface.

The Unit Housing

The unit housing will be made of Cretaceous/Paleogene (K-Pg boundary) layer rock sourced from a disused mine in Maastricht, Netherlands. K-Pg boundary sediment encapsulates Earth's most prominentinfrasound event, set off in the wake of a catastrophic meteorite impact 66 million years ago responsible for the extinction of the dinosaur. The K-Pg is the upper-most layer of the Masstrichtian geological epoch, a term that was coined by the Belgian geologist André Hubert Dumont in 1849 in his survey of southern Dutch limestone. Clay sediment of the so-called 'boundary clay' in Limburg's Mastrichtian stone constitutes a material recording of mass extinction. Its sedimentation structure indicates global tsunamis and violent storms in the ensuing 'Global Winter'. Its mineral composition and microfossil content inscribe in soil consequences of the Chicxulub meteorite impact thousands of kilometers away in the Yucatán, Mexico.

Coding in collaboration with Andrea Vogrig