Sound layers are peeled back through remoteness by traveling to a desert region in northwestern New South Wales Australia in an attempt to record the lowest natural sound layer and as close to a naturally occurring silence in our sound world. All recording locations are located between Bourke and White Cliffs. To avoid the levels of urban sound environments we leave the city, to avoid the sounds of people we leave the town, to avoid the sounds of traffic we leave main roads, to avoid the sounds of animal life and flowing water we travel to a barren landscape, to avoid any wind other than a gentle breeze we aim for still weather. The anthrophony of human infrastructure and function is escaped and biophony eventually minimised in a search for the sonic substructure in the natural world. This is the recording target; it may be seen as a base level room tone of the natural soundscape. It is an example of extreme natural quietude verging on silence, a hidden, very rare, and ancient sound that precedes complex life.
The primary question asked is:
- What is the lowest sound layer of the natural soundscape within our human hearing range and can it be recorded?
The following recordings are a selection of short examples from this recording trip and some of the quietest places on the planet. Distant and very quiet birdcall is heard, the occasional fly buzzing past the microphones, but of most interest are the very quite subtle winds that can be just heard blowing over the landscape, this is the lowest form of geophony that forms the sonic substructure of these areas. The locations and recordings do get progressively quieter as they move to more remote areas, although these are subtle changes. Given the extremely quiet locations these are VERY quiet recordings, in postproduction I have increased the level by +6dB for easier listening. The very low level signal on location means system noise is significant in these recording, for this I have also used basic noise reduction to remove some system noise but have also been restrained in using too much to leave the recordings relatively untouched. Stereo and ambisonic recordings were captured but only stereo recordings are included here, the ambisonic mic was deemed to contain too much system noise for such delicate environments. Any future recordings of near silent remote places would see the use of microphones of less noise in an attempt to capture further details of these very quiet and delicate soundscapes. These recorded excerpts are of environments unique in their quietude.
Bourke-Milparinka road saltpan.
Next to the Bourke-Milparinka road a small saltpan is recorded. Low level surrounding birdcall, wind, and traffic on the main road approximately one hundred metres away. Yet, between the cars this location is surprisingly quiet given its proximity to industrial cotton farms.
Snakes Gully Rd.
Along Snakes Gully Rd to Fords Bridge, is a plain with larger eucalypt trees to the east. This area appeared to be recently untouched with no current evidence of human or animal tracks in the soft sand. Stronger wind gusts, birdcall, flies buzzing, and distant bleating from a herd of goats under the eucalypt trees. Given goats are an introduced species this could also be seen as a form of anthrophony introduced to the soundscape.
Heffernans Lane.
The following morning at Heffernans Lane near the northern entrance of Nocoleche Nature Reserve hears a passing car and mid morning birdcall in the taller trees near to the Paroo river. Certainly not a quiet location or recording but it does show the progression to near silence.
Along the main Bourke-Milparinka.
Further along the main Bourke-Milparinka road a barren area of minimal immediate vegetation was selected. Even though distant and quiet, birdcall is surprisingly present with birds in the surrounding but minimal tree coverage, this recording has been increased in volume emphasising the birdcall. The slight gusts of wind against the microphones are exaggerated in the low-level recording with volume increases in postproduction to hear the very quiet soundscape further emphasising these. Of most interest, the very gentle gusts of wind blowing over the landscape can be heard in amongst the birdcall.
Quietest daytime recording.
A further 24km south we come to the quietest daytime recording within this research and what is surely one of the quietest places on Earth. This recording captures an example of the natural, ancient, near-silent sonic substructure of the natural environment. Here there is occasional distant birdcall, and areas of only the gentle winds blowing across the landscape between stronger gusts that are heard against the microphones. On location my ears strain to hear anything throughout the 30min recording process, the soundscape is crisp. When talking towards the microphones to give location details words seemingly dropped to the ground as they do in an anechoic chamber with no surfaces other than the soft dirt ground to reflect frequencies. When speaking at approximately five metres behind the car, the area is quiet enough to hear my voice bouncing of the car; the presence of the car itself is heard as a sonic obstacle interrupting the base level geophony.
Night recordings at campsite.
14km along the road a final recording is captured at night and is the quietest recording on the ground in this research. These two recordings captured, one at 7:20pm and the second recording beginning at 8:30pm running into the night for 4 hours. Sleeping outside on the ground in the silence without the act of recording, allowed time to listen in detail. The biophony was almost non-existent except the few occasional bird and insect calls, for instance the insect call at the beginning of Night Recording 1. In the still of night with very little wind in the immediate vicinity, night is quieter than day. The ear strains to hear
any environmental sound at all and mostly none is detected, it is a natural and extreme quietude. In the original long recording, occasional sparks from the low campfire are heard from approximately 30m away, also providing a useful reference for noise reduction. The short sharp clicks work as a location reference sound in the quiet of the desert, the sonic definition of the higher frequencies indicate how much noise reduction is being applied and whether this is affecting the recording of the sonic environment and removing any of the soundscape. In the second excerpt Campsite Night Recording 2 at 5 seconds, 14 seconds, and 60 seconds examples of very gentle, low-level winds can be heard seemingly blowing across the landscape.
However, as previously stated there is still a sound present other than simply that of my hearing system. On location and in recording there are no clear sound sources in the immediate vicinity so it is thought this is made up of surrounding gentle winds resonating over the landscape. There are instances of slight winds heard in the recording as a gentle howling.
Suitably, these final two night recordings in the progression capture the quietest environments and mark the final exterior recordings on the ground within my research. The sound layers are peeled back through remoteness, become increasingly delicate, and reach the lowest level possible with a final night recording. These are examples of the quietest possible natural environments that contain an ancient and exceptionally rare sound free of animal life with only the vegetation contributing to the sound of very subtle winds. This is the lowest sonic substructure thought to be, at least in part, comprised of gentle surrounding winds that combine to create a subtle din. The locations and resulting recordings hold characteristics similar to an anechoic chamber yet there is still sound present.
