Music has an incredibly powerful effect on the brain. It has the power to change your mood, enhance it, make you feel things that few other mediums can or to transport us to another time and place entirely. We've all had the experience of going about our day innocuously enough, only to hear a stray bar of music or lyric from a song and be instantly transported back to another time in our lives. If you're running a business or a brand, that's not something you can afford to ignore.

Indeed, studies have shown that music activates numerous parts of our brains, including those associated with the processing of emotion. It's been said that music expresses something that can't be achieved through other means. While that's true (even Thom Yorke, lead singer of Radiohead, couldn't quite pin down the effects of music in his recent episode of Desert Island Discs) neuroscientists are beginning to get close.

Malini Mohana, a Neuropsychology researcher working at the University of Cape Town, South Africa, says that music functions as a form of 'perceptual illusion' much like a visual collage. Our brains create structure and meaning around sequences of sound and basically create whole new systems of meaning.

It stands to reason, then, that music can be a powerful tool in making an impression on our customers and setting a tone or feeling for our brand or business. This isn't new stuff, although in an age of heightened global competition and online marketing it may be getting a little more scrutiny from businesses looking to gain an edge. Academics have been studying the effect of music at retail since Dr Ronald E. Milliman did groundbreaking research into how background music impacts the behaviour of shoppers as far back as the 1980s. It has been shown to be just as impactful as visual elements and branding, for example.

Music is, quite literally, your brand's voice. It's the soul and inexpressible feeling of your business that says something to your customers about who you are at a gut level.

You can use it in different ways. In a physical space, Soundtrack Your Brand's in-store music researcher Jasmine Moradi says that the best music should create an enchanting atmosphere but operate below the level of perception.

It used to be difficult for retailers to monitor music across multiple different locations and to ensure that staff didn't simply play whatever they wanted to listen to, but with new technologies it's becoming more possible to track and enforce.

Two places where brands remain in control of the music that represents them, however, are in advertising materials and in online spaces.

In days gone by, when the world had become less saturated by advertising and consumers weren't as savvy (and cynical) as they are today, businesses could be a little more on the nose with their messaging.

In 1971 Coca Cola told the world that it would 'Like to Teach the World to Sing', with a chorus of thoroughly wholesome-looking singers cheerfully crooning about world peace and letting us know that they'd like to buy the world a coke. To modern ears this blatant association of a fizzy drinks brand with fuzzy sentiments about bringing the planet together sounds way too blatant a marketing ploy, but for a generation of shoppers a bar or two of that song still brings back a palpable feeling of cheerfulness.

In online spaces music can be used in more subtle ways, however. Take a brand like 888ladies bingo. It's a business that's bringing what was traditionally a bricks and mortar form of entertainment into a digital space. However, in transitioning away from a social setting that comes with the company of friends and the background chatter of other players, something could be lost. Land-based Bingo Halls don't usually play music to ensure that the calls are audible to customers, but without that background chatter that's less of an issue. 888ladies fills that space with music, and by introducing music it's able to recreate the sense of atmosphere that might have been lost by shifting to a digital space.

Another strong example of music being deployed well by brands, of course, is in the annual round of Christmas adverts. As noted, however, businesses like Coca Cola or supermarket chains can't be as on the nose as they were in the past (unless, as you sometimes see with Coca Cola, they're opting to illicit a kick of nostalgia by re-releasing an older ad). Instead they need to score adverts with music that simultaneously tugs at the heartstrings while not feeling retro, schmaltzy or cheesy.

Apple's use of Billie Eilish's 'Come Out and Play' is perfect in both its representation of the brand and the effect it achieves in its Christmas ad. Apple's target audience are young (in spirit, if not physical biology), current, contemporary, on-trend, creative and (as much as a mass audience for a single brand can be) individual. That is what the Apple logo on the back of your laptop or phone should, in theory, express about you.

In practice, of course, the audience is much broader than that - ranging from working class teenagers who have grown up in deprived areas to pensioners walking their dogs in Hunter wellies - especially in the smartphone category.

Apple's choice of music, then, must represent and appeal to its perceived young, hip audience while not alienating its actual, much broader audience. 'Come Out and Play' straddles the divide perfectly, carrying a strong hint of credibility while being a safe choice for the sort of viewer who still buys CDs at the supermarket. Simultaneously it's a) quite a good song and b) takes the viewer on an emotional journey that mirrors the narrative arc of the ad and leaves on a warm fuzzy note at the end.

Whether you're a worldwide tech giant like Apple, an online entertainment offering like 888ladies or a bricks and mortar retail store, the smart and thoughtful use of music can do a lot to both represent your brand and enhance a customer's specific experience with you.