In 1977, NASA's Voyager 1 and 2 were launched from Earth and were to become the first space probes to reach out beyond our solar system and into interstellar space.
Along with all the experiments onboard was The Golden Record — Earth's cosmic calling card.
On it was a collection of music, voices, and animal sounds.
The idea was that should aliens encounter Voyager, one of their first impressions of our planet would be of its sounds.
That got us at ABC Science thinking — what sounds would we put on our own record to represent our corner of the earth — Australia?
As a radio presenter, Dr Ann Jones has spent her career recording and collecting sounds, making her the perfect host to take us on a sonic and visual odyssey across the country.
To create a two-part Catalyst television program on sound was an ambitious undertaking.
It required two crews filming for a total of six weeks to travel the country and record over 200 bespoke sounds from which we've created our own "golden" vinyl record called The Soundtrack of Australia.
We wanted to start the show in silence — well, as close to silence as we could find in the natural world.
We chose Warinburna, or Lake Cowan, which is a salt lake near Norseman in WA.
The remoteness of the location and lack of vegetation (no leaves to rustle in the breeze) meant we could demonstrate how even one of the quietest landscapes was still awash with sound.
We recorded wisps of wind, the buzz of a fly and the roof of our tent flapping.
Microphones were attached to each of Ann's boots, allowing us to record in stereo a hyperreal sound of the crunch of her footsteps over the salt.
In order to "see" soundwaves, we invited Aussie beatboxer Tom Thum (who is capable of unbelievable vocal gymnastics) to our acoustic shed.
Loading...With the help of physicist Dr John Debs from ANU, the shed was set up with various equipment, including a Rubens Tube and Chladni Plate, which allow us to see frequency and resonance.
For timbre, we chose one of the most iconic Australian sounds — the didgeridoo.
Ngemba man Kristian Benton showed us how part of the instrument was fashioned by termites — giving each one its own unique timbre.
To hear the rhythm created by Kristian's lips, a microphone was placed close to his mouth, another at the end of the instrument and one placed 10 metres away, to capture the natural reverberation.
No soundtrack of Australia would be complete without one of nature's greatest mimics, but lyrebirds are a notoriously elusive bird.
We'd been liaising with Dr Alex Maisey for weeks about the best times and locations to find a lyrebird singing — he's the go-to man for spotting one — but it wasn't really peak singing season.
A few days before we arrived, he'd taken a French film crew out to try and film some displays but after three days of trying, they'd had no luck.
We knew it was a long shot, but our plan was to get there at the crack of dawn and just wait. Maybe we would be luckier?
Loading...There were some hopeful sounds as we began unpacking the car and headed into the dense tree ferns.
There were definitely some birds about.
Suddenly the crew was running, grabbing gear and hurling cameras onto tripods as fast as possible.
Ten minutes after arriving, there in the bushes, about 100m from where we'd parked, was a male bird giving his best recital.
As we began filming, an even more incredible piece of luck — a young male came up to watch and learn from the display.
This was the most amazing example of the transmission of sounds from one bird to another — exactly what we'd come to the forest to talk about.
After about 20 minutes of filming, with everyone watching on in awe, the birds went about their business.
Ann turned to the crew and joked: "Right then, that's in the can! What do we do for the rest of the day?"
Lyrebirds weren't the only elusive animal we wanted to record.
In order to explore infrasound — sounds below 20Hz that humans can't hear — we set off on a boat trip to Perth Canyon, 20km west of Rottnest Island, WA.
We needed to find one of the most rarely sighted species of whales on the planet – the pygmy blue whale.
The trip on the whale ship was the opposite of the lyrebird story — more of an "endurance" story.
Because the whales are so rarely seen, we'd taken the precaution of sending a spotter plane up so that we would have some clue about which way to go but, after hours of flying, they hadn't seen any.
So, to find them, we had to rely on sound, using sonobuoys to detect their infrasound calls.
An hour later, we finally heard whale song and motored towards it.
By this time, we'd been out on the choppy seas for five hours and both our camera assistant, Amir and sound recordist, Nick, were feeling the worse for wear.
Nick was mid-vomit when a whale was finally spotted.
With valiant dedication to his craft, he raced to the bow of the boat to capture the sound of the whale exhaling.
He missed the first one, but fortunately, the whale surfaced again and he managed to record the second one.
Loading...There are also sounds that break all the rules, called sonic booms or shock waves.
If a sonic boom is big enough, the shock wave it creates can kill.
To understand how they work, we filmed a 2kg explosion with a high-speed camera to capture the fleeting, transparent shock waves as they emanated out.
The crew took up a safe spot 300m from the blast site.
Sound recordist Leo Sullivan remembers: "It was quite extraordinary because we were a fair distance back from the blast and the explosion just looked like a little puff of smoke, but when the sound hit us it was huge! I could feel the shock wave hit my chest."
Our last stop was a trip to The Dish.
For decades, it was thought that in the vacuum of space, sound couldn't exist.
But scientists discovered a black hole in the centre of the Perseus galaxy cluster which has been found to emit pressure waves — the very nature of sound.
If you've ever wondered what space might sound like, it would probably be close to this:
Loading...It took some doing, but now our recording of the country's sound is ready for audience ears.
The two-part Catalyst program, The Soundtrack of Australia, begins Tuesday, August 15 at 8:30pm on ABC TV and iview and the entire soundtrack can be heard on Nature Track podcast on ABC Listen