The system, called Soundtrack Your Brand, plays music that reflects a brand's values, evoking a range of positive emotions in customers and increasing guest satisfaction.
Researchers from HUI Research, a research-based consulting firm in Stockholm, conducted the largest ever academic study of background music, to design the system.
Professor Sven-Olov Daunfeldt, who led the study, said: 'This is without doubt the largest field study on the influence of music in restaurants to date, and we've analysed an enormous pool of data.
'When done right, music has a major positive effect on sales, largely stemming from guests purchasing more items such as desserts and sides.
'Play the wrong music, and you just might find that you're alienating that very same customer and selling significantly less.'
While most restaurants play music in an attempt to shape their customers' experience, they choose their songs casually and without much thought.
Over the course of five months, across 16 McDonalds restaurants in Sweden, the researchers analysed a pool of nearly two million unique transactions. In particular, sales of desserts and sides rose by more than 11 per cent, while the sales of smoothies and milkshakes increased by 15 per cent
Over the course of five months, across 16 McDonalds restaurants in Sweden, the researchers analysed a pool of nearly two million unique transactions.
The results showed that the difference was 9.1 per cent over the period of the study.
Music that fit the brand made customers more likely to buy additional items than if the restaurant played random popular music.
The formula for success appeared to be a mix of popular and less known songs that still had a good brand fit.
Ola Sars, CEO of Soundtrack Your Brand, told MailOnline: 'The Soundtrack Your Brand technology takes into account factors such as the time of day and the type of people likely to be in a certain location, creating a tailored atmosphere for both the brand and consumer.