The familiar Sydney sound spliced into Billie Eilish's Bad Guy

<span>Photograph: Frederic J Brown/AFP via Getty Images</span>
Photograph: Frederic J Brown/AFP via Getty Images

If you listened carefully, you might just have heard it. Sitting underneath the pulsating chorus of Billie Eilish’s Grammy award-winning smash hit, Bad Guy, there is a familiar sound for many Australians: the rapid tick you will hear at a pedestrian crossing when the light turns green.

The 18-year-old, who was the big winner at this year’s Grammys, picking up gongs including best new artist, album of the year and song of the year, revealed she used the Australian-themed sample in an interview with Rolling Stone late last year.

But new and more casual Australian fans might have only been made aware of the local connection – albeit a small one – after Eilish became the first female winner of Triple J’s Hottest 100 at the weekend.

Related: Billie Eilish becomes first solo female artist to win Triple J Hottest 100

It turns out the sample was recorded on Eilish’s iPhone. “My mum and I went for a walk in Sydney,” she said. “We were like across the street from the hotel and the crosswalk is this little – you press it and it’s like ‘doop, doop’. And I was like, ‘That’s hard!’ That’s the sound that it makes when you have to wait.”

Eilish then plays the interviewer the recording. “And then I was not prepared for this part,” she said.

And then light turns green on the recording. “That scared me,” Eilish is heard saying in the iPhone recording.

Related: Catharsis queen: how Billie Eilish became the voice of Gen Z – and the Grammys

Her brother, producer Finneas, told Rolling Stone that the recording of the crossing sound needed some work before it could be used in the song. “Unaltered it’s not the right speed,” he said.

“The hilarious part about all this is we were just in Australia in May and my dad goes, ‘Have you heard these crosswalks?’

“And I was like, ‘Yeah, it’s the chorus in Bad Guy.’ And he goes, ‘What?’ I was like, ‘Yeah … never mind man.’”

Bad Guy, taken from her album, When We All Fall Asleep Where Do We Go?, was one of five songs Eilish had in this year’s Hottest 100.

Sydney’s traffic light buttons were designed to meet the needs of blind and visually impaired people and rolled out from 1984 onwards. They were later exported to other countries including the US, New Zealand, Ireland and Singapore.