The Australian Navy needed to recruit Electronic Spectrum System Operators. It’s an intelligence role that’s difficult to recruit for and involves identifying threats at sea by manipulating frequencies in the electromagnetic spectrum – also known as The Invisible Battlefield. So, that’s where we ran our ad. With a small budget for social media, we created a single audio file that was so much more than something to listen to. We challenged people to analyse it, decode it, manipulate its frequency content and discover its hidden message – a poster, painted with sound.

An enigmatic yet assertive voice tells us we’re taking part in an exercise for the Australian Navy. The voice tells us to listen closely as we hear strange beeps and bloops. We're challenged to analyze the audio with a spectrogram and the voice suggests there’s something yet to be identified. Suddenly, the transmission ends, but it's not over yet. By roleplaying as an intelligence officer in the Navy and analyzing the audio file with a spectrogram, listeners are rewarded with something unexpected: a hidden image in the form of sound that revealed the role in the Navy we needed to recruit for.

This audience is notoriously hard to reach. They’re interested in technology and problem-solving, so connecting with them required an idea that challenged them and invited participation. The Audio Ad You Can See did that – it asked them to roleplay as an intelligence officer and use the same technology they would in the Navy. Not everyone could find the hidden message, so we knew the people visiting the job page were high quality candidates – they had found the direct link to the website. The collection of data was a simple process in tracking downloads, streams, social interactions and visits to the job page.

First, a designer created a poster, which was converted into audio using an image synthesizer, before the voice and soundscape elements were added. Extensive use of additive EQ, subtractive EQ, compression and the micro-automation of volume were meticulously used to ensure each sound had its own sonic space in the frequency spectrum. Essentially, the audio engineer was painting with sound. The audio also contained other hidden sounds to misdirect the audience, such as sonar pings, whale sounds, muffled communications, and Morse code – with its own hidden message that spelled out ‘Keep Looking’.

This was one of the Navy’s most successful direct recruitment campaigns. On social media, it had more interactions than any other organic post from Australia’s Defence Forces with 512% more impressions, resulting in 80 times more engagement with the job listing, all from high quality candidates. The media reach also helped position the Australian Navy as an innovative and tech-based employer for anyone interested in science, technology, engineering and mathematics. The Audio Ad You Can See gave high quality candidates an experience that went beyond listening to an ad or looking at a poster – it put them in the shoes on an Electronic Spectrum Systems Operator and helped them imagine a career in the Navy.