here is the abstract for the article:
"Silencing and musicalization, as defined by Douglas Kahn, are valuable means to call attention to the sonically liminal. They create a frame within which acoustic silence can be attended to, either as a conceptual phenomenon or as the dead silence of sounds and soundmakers subjected to ecological silencing. Through critical discussion of silence in Kahn's writing on John Cage, as well as in acoustic ecology and soundscape composition, an outline of ecological silencing is developed and applied through the examination of environmentally engaged sound works by Sally Ann McIntyre of New Zealand and Katie Paterson of Great Britain."
and an excerpt:
"Ecological silencing is properly understood as an ecological event. Indeed, there's very little discussion of silence per se in Rachel Carson's epoch-making environmentalist text Silent Spring. Carson's concern was not for silence itself, but silence as a symptom of dangerous human interventions into the natural world: silence as an outcome of the effects of synthetic pesticides, DDT in particular, on the biosphere. In the book's opening chapter, Carson describes a fictitious but typical mid-20th-century American town blighted by the effects of "a white granular powder [that] some weeks before had fallen upon the roofs and the lawns, the field and streams." The outcome of this dusting of pesticide is a "spring without voices. On the mornings that had once throbbed with the dawn chorus . . . there was now no sound; only silence lay over the fields and woods and marsh". In this context, aesthetic concern for silence itself sounds inappropriate. Silence, as a signal that all is not well in the biosphere, is to be filled with the sonic abundance—noisiness—that signals a healthy ecosystem. The sonic image of a silent spring is a powerful one, and as a pioneering environmental activist Carson successfully deployed this image to mobilize public opinion against synthetic pesticides in the United States. The aestheticized, which is to say musicalized, sound-image of a silent spring, itself inspired by a line from Keats's poem La Belle Dame Sans Merci ("The sedge has wither'd from the lake, / And no birds sing."), is a means to sound out the real-world problem signaled by silence.
For contemporary sound artists engaged with environmental matters in which silence plays a role, the question is: How to make dead silence speak? How to represent and deploy it meaningfully and in ways that do not cloak it in the habits of silence associated with Cage and acoustic ecology? One of the most problematic silences for both Cage and acoustic ecology is the substitution of recorded for live sound. The fear here, following Jean Baudrillard's theory of simulation, is that the recording silences the living, sounding thing. This perennial concern, encapsulated in Schafer's concept of schizophonia as an aberrant technological phenomenon, is as old as recording technology itself. In contrast to this perspective, however, recording can be used to musicalize acoustic silence as the horizon of the audible, bringing it into dialogue with Cagean silence and, as we will shortly hear, creating a powerful affective tool through which to address ecological silencing.
The musicalization of acoustic silence is made possible by the intentional act of recording that functions as a framing device for acoustic silence. This is a Cagean move: the giving of duration to something that is without duration, just as 4'33" gives form to the silence of the place of listening, thereby calling attention to what is acoustically present there. If nothing is acoustically present, or if the thing being recorded cannot be acoustically present, then recording—and listening—draws attention to the acoustic silence of that thing. Such a move can be conceptual, as in Yoko Ono's Tape Piece III or artist Julian Dashper's recordings of canonic artworks of the 20th century. When the intention of the work is ecological, however, acoustic silence takes political form; the gap between the acoustic absence of silenced thing and the Cagean silence we hear around it calls attention to the irrevocable loss inherent in that heterogeneous silence. This is achieved in Sally Ann McIntyre's transmission arts piece, Collected Silences for Lord Rothschild (2012), which replicates Dashper's move but with an ethical-environmental dimension:
Recordings of the mounted specimens of two species of endemic New Zealand birds, the Huia (Heteralochaacutirostris), and the Laughing Owl or Whekau (Scelo-glauxalbifacies) held in the collection of The Museum of New Zealand Te Papa Tongarewa. Both these species were driven to extinction, partially through the actions of European collectors, in the early 1900s. They were both still recorded as alive during the twentieth century's first blossoming, after the invention of recording technology, but neither of their songs are on record.Making dead silences speak may also be predicated not on acoustic silence but, taking a conceptual turn, by evoking the ecological silence of an extinct thing through sound. Another work by McIntyre, Huia Transcriptions (2012), uses "transcriptions to music box of one of the few extant accounts of the calls of Huia (Heteralochaacutirostris), as notated by a Mr. H. T. Caver in the late 1800s," which are "played back in the early morning chorus into forest areas of Kapiti [Island, NZ], amplified non-electronically on the trunks of species of trees Huia would likely have climbed". What this allows us to hear, negatively magnified through the audible presence of living birds, is the silence of the extinct Huia, as the simple transcriptions and music box realization of these fail, poetically and affectingly, to do anything more than gracelessly approximate a call known only through musical and textual descriptions.
The schismogenesis of recording, a more productive conceptual cousin to Schafer's schizophonia, also plays a vital role in environmentally engaged sound art such as McIntyre's. Schismogenesis, in Stephen Feld's use of the term (itself borrowed from Gregory Bateson), brings a new kind of sonic entity into being, which reveals aspects of its live source but is not the same as this source. This is a useful word for a familiar idea, much beloved by phonographists of all kinds: Schismogenesis is what made possible the soundscape analyses of the World Soundscape Project as well as the sonic discourse of Schaefferian musique concrète. Yet the recording does not and cannot substitute for the absent source, despite the presence of its acoustic trace. In this way sonic schismogenesis has a melancholy ontology, a cousin to the melancholy of the photograph as conceptualized by Roland Barthes  , which always points to the loss or lack inherent in the photograph's highly delimited capture of the past in the form of chemical traces of light. As with photography, recording is a time-binding technology that, unlike photography, has protensity (continuation in time), but like photography can only point to a past reality. Following Heidegger, it can be said that recording reveals, but an inescapable aspect of this revealing is to expose the limits of recording technology: The recording (or better, phonograph), like the photograph, points as much to what it cannot do as to what it can do. Sounds can be captured and restored but their sources and makers cannot be. Protensity can only be simulated in the recording. Sonic schismogenesis therefore always has the grain of sadness, of loss, in its timbre. In the context of ecological silencing, and the presencing of the acoustic silence that signals it, the recording affectively heightens the profundity of the ecological loss of sounds and their makers: "All recordings are historical documents that will hold relevance for future generations, especially as environments continue to change and species become rare or extinct"."
the essay can be read and downloaded in full here: Dead Silence: ecological silencing and environmentally-engaged sound-art