From Jesse’s PhD exegesis:

Mobilong is an English corruption of moopolthawong (from the Ngaralta clan, of the Ngarrindjeri nation) meaning ‘haven for birds’.

The contemporary Mobilong is part of the Lower Murray Reclaimed Irrigation Area (LMRIA) and is situated north of and adjacent to the Rural City of Murray Bridge, South Australia. The area was originally a natural floodplain, with the water table level subject to seasonal fluctuation of the Murray River. This cycle replenished the related aquifers, with the highly saline groundwater subsequently discharging into the river basin. European settlement in the late 19th and early 20th centuries brought reclaiming of the floodplains for irrigation, and intent for the Murray to remain a constant water source (for agriculture and navigation) saw the introduction of locks, barrages and levee banks along the river channel. Drainage channels and irrigation cycles artificially replicated the natural filtration process, but multiple droughts in between 2000-2010 saw significant drops in the river level and water table, in turn impacting irrigation activities via reduced water availability. Thus, the saline groundwater rose, and the substantial clay soil profile acidified, compromising agricultural and farming activities. Since 2010, the acquisition of much of Mobilong by SA Water has seen the trial of various remedial activities. Several eucalyptus trial plantations are being trialled, and there is discussion around natural filtration through the diversion of acidic water discharge through local wetlands (EPA 2013; Sims 2013). Consequently, the environmental, ecological and sociocultural histories of this area result in its current biodiversity, and the related soundscape that arises through ecosystem function.

Conception and Collation

As Mobilong Swamp is little more than a kilometre away from my home in Murray Bridge, I have a close connection with the area. My first creative connections with the site began back in late 2014. One evening, I was walking along Pump Road, an 880 metre stretch of unsealed road which bisects the swampland, and began to notice the dynamic and stereophonic quality of the soundscape, with stridulating crickets, chorusing birds and croaking frogs sounding either side of the road and at the riverfront. Fascinated, I resolved to respond to this site in creative work, following a real-time experience of a sound walk along Pump Road at dusk, extending from the western cliff faces (at the Pump and Toora Road intersection) to the eastern riverfront. This original intention remained unchanged from the work's initial conception to fruition.

Derived from the sound walk experience of Pump Road, the overall form of the piece is an idealised procession of the observer (audience) along the road towards the river, in line with the setting sun’s shadow cast by an abutting cliff face (at the foot of Pump Road, to the west).

Despite my engagement with the place, it was not until later 2015, involved in creative research, that I began a more thorough investigation of Mobilong and its ecosystem. This involved a variety of approaches that included reviewing published literature, discussions with numerous people connected to place, and on-site observation.

After contact with the Rural City of Murray Bridge’s environmental officer, I was referred on to a local contractor, Bob Chapman (previously a dairy farmer at Mobilong, whose family had worked the land for many generations. Bob, in turn, put me in contact with numerous environmental resource managers: SA Water Land Manager, David Loveder, and Dr Luke Moseley of the Acid Sulphate Soil Centre at the Waite Institute, University of Adelaide.

Through these connections, I was able to access environmental reports on the Mobilong Swamp area from the EPA (2013) and SA Water (Sims 2013), and survey maps from the Rural City of Murray Bridge Council. Additionally, a list of local birds was sourced from a nearby bird hide at the Rocky Gully Wetlands. These information sources (human and text/visual) allowed me to develop an understanding of the ecological evolution of the space, as it related to Ngarrindjeri and European historical uses of the land, and the significant changes in the landscape (and by extension, the soundscape) in the past decade.

Subsequently, I began to visit Mobilong periodically in mid-to-late 2015, as its proximity to my home allowed for ongoing visitation and monitoring. This consisted of observation, documentation and sound recording. Recordings were made with a Zoom H6 with an X-Y microphone capsule in each distinct land patch to capture discrete sonotopes (discussed further below) between November 2015 to April 2016.

Additionally, I had the opportunity to observe a field trip at Mobilong on 30 October 2015 by Acid Sulfate Soils Centre researchers Dr Luke Moseley and Professor Rob Fitzpatrick, supported by a visiting German scientist. Collecting soil and water samples from compromised land patches and irrigation channels, the team provided explanation and insight into the ecological impact of soil and water acidification, and ongoing remediation strategies at the site.


Preparation and Composition

The preparation and composition of Mobilong was an organic process in which both micromorphological and macromorphological details were addressed, mutually informing one another to arrive at the creative result.

The processes of conception and collation gave rise to perspectives and contexts that directly informed how the collated materials were creatively adapted. Of particular interest were ecological considerations, as including soil conditions, biodiversity distribution and related sonic spatial distribution, and to topographical and meteorological activity.

First, the acidification of large soil patches resulting from irrigational land use and recent droughts has directly impacted on the species of flora able to survive in the area. The most impacted areas are now populated mainly by samphire and saltbush, by comparison to more alluvial soils which support various grasses and reeds (particularly Phragmites australis). As part of ongoing land management, numerous trial plantations of eucalypts, including river box (e. largiflorens) and river red gum (e. camaldulensis), have been introduced to remediate soil conditions.

This floral distribution, combined with striated boundaries including fences, channels and transport infrastructure, has created distinct habitats, or ecotopes with associated fauna. These appear to be in four general types: grassed fields, occupied by small songbirds, birds of prey and crickets; saltbush fields, still occupied by such birds but with no crickets; plantation, populated with a greater variety of small to medium perching and songbirds; and riverfront, with a notable presence of water birds and frog species. The overlapping geophonies and biophonies of these ecotopes, in turn, creates distinct sonotopes or acoustic communities (Farina & James 2016; Mullet, Farina & Gage 2017) through which an observer can pass, experiencing subtle but dynamic changes of acoustic communities in the soundscape. In a creative context, this experience provides a natural crescendo, building from a sparse beginning to a climactic finale.

Mobilong Swamp also features an interesting relationship between its topology and diurnal activity. At particular times of the year, when the sun’s azimuth is directly in line with the cliff at the junction of Pump and Toora road at dusk, a shadow is cast that gradually proceeds from the cliff face towards the water. This has important implications on the dusk soundscape: in addition to vocalising bird life and frogs, crickets in the field change their calling frequencies in response to the falling temperatures (Walker 1962), in turn affecting the collective drone of the chorus.

These observations were adapted creatively and subsequently implemented.

In order to recreate the sound walk experience in a static performance setup, I realised that the sonic materials would need to move from in front of to behind the audience, with the site’s spatial relationships (road and fields) preserved by situating associated sounds to either side. Given the intended combination of acoustic instrumentation and electronics, an octophonic speaker setup was chosen with four separate groups of performers situated between each of the side speakers. As such, the sonic materials progresses from front to rear, alternating between the speakers and live performers, and evolving as new sonotopes within the soundscape are encountered.

To achieve this, the Council survey maps were annotated with distance measurements made with Google Maps of each distinct land patch along the road. From progressing at a virtual walking rate of 4.8kh/h (20 metres per 15 seconds), these distances were then converted into durations (in seconds), providing specific time cues for formal transitions between sonotopes (i.e. a change from ‘saltbush fields’ to ‘plantation’ field recordings). Further, the material, played from Front Left and Right, and Rear Left and Right speakers, was conceptualised to be 60m away from the audience to create a sense of immersion and transition in the environment, and accordingly, the time cues for sonotope transitions were offset by 45 seconds in either direction.

Electronics

Utilising field recordings made in each of the identified sonotopes on site, the acoustic environment was reconstructed in Ableton Live 9 (and later adapted to Live 10), according to the temporal calculations made earlier. Field recording material situated in the front and rear speakers was attenuated relative to the centre speakers, aiming at replicating real- world distance attenuation.

Instruments

For Mobilong, I settled on the string ensemble as instrumentation predominantly due to the timbral versatility possible through bowing position and extended techniques. This, I felt, would sufficiently replicate the diverse biophony of bird, cricket and frog calls, as well as a selection of geophonic gestures such as bowing the body of the instrument to evoke wind rustling through reeds or tree.

Rather than attempting to identify each species through direct observation, to save time I referred to a list of birds found previously at the Rocky Gully Wetlands bird hide, and located many call recordings made by Fred Van Gess on the website Birds In Backyards (www.birdsinbackyards.net/) and Michael Dahlem (https://mdahlem.net/). With their permission, I began transcribing the calls.

In contrast to the direct notation approach of Olivier Messiaen and John Luther Adams, whose transcriptions were made listening in the field and subsequently used in Catalogue d’Oiseaux and songbirdsongs... respectively, I instead used computer-aided spectral analysis. Calls were first analysed and processed in SPEAR, viewing each call’s spectral envelope and pitch content. Simpler pitched calls were transcribed by using fundamentals as the basis of the melodic trajectory, and partial density conveyed through bowing position (from fewer partials with sul tasto to more partials with sul ponticello); whereas complex and non-pitched/percussive sound materials were transcribed through appropriate extended techniques.

Similarly, the cricket chirp transcriptions were achieved via spectral analysis, with stridulation imitated by an indeterminate ricochet bowing on extremely high pitches. Considering then the topographic and barometric conditions of Mobilong at dusk, where the western cliff casts a shadow gradually proceeding towards the riverfront (between illuminated and dimmed areas in addition to the cooling of air temperature), the cricket chirp pitch content was organised to slowly and microtonally descend over the piece’s duration. The sounding result of combined individual calls, reinforced in the electronic track, evokes a subtle descending high-pitched drone.

This was followed by the assemblage of the score for each string ensemble, made up of violins, violas, and cellos. Devised as a modular score where each performer plays the transcribed materials at their discretion, the content is comprised of transcriptions of bird song, cricket stridulations and geophonic activity. Like the electronic counterpart, each ensemble’s content is temporally correlated with the site’s habitats and associated sonotopes, using time cues to remain synchronised.

When making initial preparations towards live performance, it became apparent that significant logistical challenges with personnel and space existed. As a result, I decided to record each transcribed module individually. Recording sessions took place in November and December 2016 with Lester Wong (violin), Hurley Baker (viola) and David Moran (cello) at the Electronic Music Unit Studios at The University of Adelaide. Each transcribed call was recorded several times and was then isolated in editing as an individual sample for use in the Ableton Live session.

To simulate the indeterminate component of the string ensembles, a Max patch ‘Density’ device, was developed that triggered calls in response to an assigned probability. Connected with an Ableton Drum Rack device with all samples preloaded, the device was able to limit the number of samples played (correlated with sonotopes via score-based time cues). This device was implemented on separate tracks for each of the four string ensembles (Front Left, Front Right, Rear Left, Rear Right), which were then panned to the respective speakers in the octophonic setup, allowing Mobilong to be rendered as an acousmatic multichannel work as well as a live electroacoustic work.

Realisation

Whilst the live electroacoustic version of the work was not performed during the research project, the acousmatic version was presented as part of Immersed: A Concert of New Surround Sound Works at the University of Adelaide on 19 May 2018, and at the Murray Bridge Town Hall on 3 June 2018, with the support of the Elder Conservatorium EMU and a Rural City of Murray Bridge Small Wins Grant.

Reflection

As the first project to implement the Ecotonal framework, Mobilong aims at a real-time representation of the swamp land’s dusk soundscape, drawing attention to the area’s current ecological circumstances emerging from historical land use. Additionally, through addressing challenges of performance logistics, approaches to representations of non- human agency (via Morton and Barad) were explored, through modular scoring (for live performance) and computer-aided stochastic activity (for acousmatic performance).

Though aiming at a real-time representation of the site’s dusk soundscape experience, various abstractions emerged as a result of creative translations of Ecoacoustic phenomena and behaviours.

Concerning temporal relationships, the Mobilong swamplands are subject to meso- and macro-level temporal cycles, in the form of seasonal/climatic changes and associated dynamics such as flooding and solar activity. To fashion a broad-scale representation of place rather than of a specific period, certain environmental processes were disregarded to preserve the creative concept or heightened performance possibilities. For example, disregarded was the fact that the sun, for periods of the year, does not fall behind the cliff with its fluctuating azimuth.

Various compromises were made with bird calls. Firstly, many bird calls were included in the transcribed call collection, discounting seasonal species variance seasonal migration and mating patterns. Additionally, some calls are pitched beyond the standard range of the violins, so the associated transcribed calls were transposed an octave lower to remain playable, with occasional (poco) sul ponticello bowing directions intended to provide compensatory higher partials. Occasionally, calls of certain bird species were deemed too complex to transcribe for the capabilities of the available instrumentation, or too variable/ improvisatory to provide meaningful instructions within the established performance methods, and were therefore not included.

Numerous human-produced sounds also featured in the real-world Mobilong soundscape, including those of the nearby meatworks, passing road vehicles, watercraft and aircraft overhead. Various pieces of infrastructure that were thought initially to produce sounds are also in situ, including wind-intoned measuring bores, aeolian harp-like powerlines, and an occasionally operated motorised irrigation pump. However, these were either absent or ineffective in the soundscape experience, or too obtrusive to warrant inclusion for this work.

Lastly, unlike a real-world sound walk, where the listener moves freely through a space, the static listener experience inherent in multichannel concert works meant that it was necessary to develop and route recorded material to specific directionally-associated tracks and speakers. Despite the stasis of listener and sound sources in performance, the shifts in content (the biophony and ambient field recordings) and distance-based amplitude attenuation give the necessary sense of transition and progression to replicate the soundwalk experience.