Popular songs are often said to have gone viral — and according to new research, they really do spread in the same way as infectious diseases. By comparing the patterns of song downloads to epidemic models, researchers from McMaster University found that the same social mechanisms are at play in both cases.
The research was led by Dora Rosati, a former graduate of mathematics and statistics at McMaster University, and published in Proceedings of the Royal Society A: Mathematical and Physical Sciences.
There are many similarities between the way a song climbs up the charts and the way a disease spreads through a population. In both cases, social interactions are key: many songs become popular through word-of-mouth, while many diseases require face-to-face interactions to spread.
Because of these similarities, Rosati and colleagues were interested in learning whether the same mathematical models could be used to describe both phenomena. They did this by analyzing more than a billion song downloads in 33 different countries over the course of seven years.
After identifying the most popular songs within their sample, the team attempted to fit the download data with epidemic models describing how diseases spread. They found that among the top 1,000 songs downloaded over the course of their study, nearly 90% were best fit by the same models used for infectious diseases.
“This suggests that the social processes underlying song popularity are similar to those that drive infectious disease transmission,” the authors said.
The team then went on to calculate reproduction numbers for each of the songs included in their study. These numbers describe how quickly a disease is spreading — an R number of one, for example, means that one person will affect one other person on average.
Perhaps surprisingly, they found that electronica music had the highest R number, with an average value of 3,430 across the songs they analyzed. This was higher than that of pop music, which had an R number of only 35 on average (and far higher than diseases like measles or chickenpox, which previously had R numbers of 18 and 12, respectively).
The researchers suspect that this may have to do with the communities behind each genre, as well as how songs within these genres gain popularity. They also note that in the case of electronica, this high infectious period only lasted for a few days.
“Electronica fans may be more passionate about their favourite songs and bands than Pop fans, and therefore talk about and promote their favourite songs more,” the authors explained.
“Perhaps Pop, being a more mainstream genre, is spread chiefly through more passive means like the radio.”
The next steps for the researchers will be to expand their analysis to music streaming in addition to downloads. Streaming is becoming an increasingly popular way to listen to music, and the authors are interested in learning whether or not these trends extend to streamed songs.
For musicians, these results could help inform future promotional efforts. Electronica artists, for example, could take advantage of the viral nature of their genre by focusing on word-of-mouth campaigns.
“Popular songs are often described as ‘viral’ or ‘catchy’,” the authors conclude, “[and] perhaps this description is more apt than has been previously recognized.”
