Music Machinery

One of the challenges faced by a music streaming service is to figure out what music to play for the brand-new listener.  The first listening experience of a new listener can be critical to gaining that listener as a long time subscriber. However, figuring out what to play for that new listener is very difficult because often there’s absolutely no data available about what kind of music that listener likes. Some music services will interview the new listener to get an idea of their music tastes.

Selecting your favorite genres is part of the nifty user interview for Beat’s music

However, we’ve seen that for many listeners, especially the casual and indifferent listeners, this type of enrollment may be too complicated. Some listeners don’t know or care about the differences between Blues, R&B and Americana and thus won’t be able to tell you which they prefer. A listener whose only experience in starting a listening session is to turn on the radio may not be ready for a multi-screen interview about their music taste.

So what can a music service play for a listener when they have absolutely no data about that listener? A good place to start is to play music by the most popular artists.  Given no other data,  playing what’s popular is better than nothing. But perhaps we can do better than that. The key is in looking at the little bit of data that a new listener will give you.

For most music services, there’s a short user enrollment process that gets some basic info from the listener including their email address and some basic demographic information. Here’s the enrollment box for Spotify:

Included in this information is the date of birth and the gender of the listener. Perhaps we can use basic demographic data to generate a slightly more refined set of artists. For starters, lets consider gender.  Let’s try to answer the question: If we know that a listener is male or female does that increase our understanding of what kind of music they might like?  Let’s take a look.

Exploring Gender Differences in Listening
Do men listen to different music than women do? Anecdotally, we can think of lots of examples that point to yes – it seems like more of One Direction’s fans are female, while more heavy metal fans are male, but lets take a look at some data to see if this is really the case.

The Data – For this study,  I looked at the recent listening of about 200 thousand randomly selected listeners that have self-identified as either male or female.  From this set of listeners, I tallied up the number of male and female listeners for each artist and then simply ranked the artists in order or listeners. Here’s a quick look at the top 5 artists by gender.

Top 5 artists by gender

Among the top 5 we see that the Male and Female listeners only share one artist in common:Bruno Mars.  This trend continues as we look at the top 40 artists. Comparing lists by eye can be a bit difficult, so I created a slopegraph visualization to make it easier to compare. Click on this image to see the whole slopegraph:

click for full chart

Looking at the top 40 charts artists we see that more than a quarter of the artists are gender specific. Artists that top the female listener chart but are missing on the male listener chart include: Justin Bieber, Demi Lovato, Shakira, Britney Spears, One Direction, Christina Aguilera, Ke$ha, Ciara, Jennifer Lopez, Avril Lavigne and Nicki Minaj. Conversely, artists that top the male listener chart but are missing on the top 40 female listener chart include: Bob Marley, Kendrick Lamar, Wiz Khalifa, Avicii, T.I. Queen, J.Cole, Linkin Park, Kid Cudi and 50 Cent. While some artists seem to more easily cross gender lines like Rihanna, Justin Timberlake, Lana Del Rey and Robin Thicke.

No matter what size chart we look at – whether it is the top 40, top 200 or the top 1000 artists – about 30% of artists on a gender-specific chart don’t appear on the corresponding chart for the opposite gender.  Similarly, about 15% of the artists that appear on a general chart of top artists will be of low relevance to a typical listener based on these gender-listening differences.

What does this all mean?  If you don’t know anything about a listener except for their gender, you can reduce the listener WTFs by 15% for a typical listener by restricting plays to artists from the gender specific charts.  But perhaps even more importantly, we can use this data to improve the listening experience for a listener even if we don’t know a listener’s gender at all.  Looking at the data we see that there are a number of gender-polarizing artists on any chart. These are artists that are extremely popular for one gender, but not popular at all for the other.  Chances are that if you play one of these polarizing artists for a listener that you know absolutely nothing about, 50% of the time you will get it wrong.  Play One Direction and 50% of the time the listener won’t like it, just because 50% of the time the listener is male.  This means that we can improve the listening experience for a listener, even if we don’t know their gender by eliminating the gender skewing artists and replacing them with more gender neutral artists.

Let’s see how this would affect our charts.  Here are the new Top 40 artists when we account for gender differences.

Artists promoted to the chart due to replace gender-skewed artists are in bold. Artists that were dropped from the top 40 are:

• Avicii – skews male
• Justin Bieber – skews female
• Christina Aguilera – skews female
• One Direction – skews female
• Demi Lovato – skews female

Who are the most gender skewed artists?

The Top 40  is a fairly narrow slice of music. It is much more interesting to look at how listening can skew across a much broader range of music.  Here I look at the top 1,000 artists listened to by males and the top 1,000 artists listened to by females and find the artists that have the largest change in rank as they move from the male chart to the female chart. Artists that lose the most rank are artists that skew male the most, while artists that gain the most rank skew female.

Top male-skewed artists:
artists that skew towards male fans

• Iron Maiden
• Rage Against the Machine
• Van Halen
• N.W.A
• Jimi Hendrix
• Limp Bizkit
• Wu-Tang Clan
• Xzibit
• The Who
• Moby
• Alice in Chains
• Soundgarden
• Black Sabbath
• Stone Temple Pilots
• Mobb Deep
• Queens of the Stone Age
• Ice Cube
• Kavinsky
• Audioslave
• Pantera

Top female-skewed artists:
artists that skew towards female fans

• Danity Kane
• Cody Simpson
• Hannah Montana
• Emily Osment
• Playa LImbo
• Vanessa Hudgens
• Sandoval
• Miranda Lambert
• Sugarland
• Aly & AJ
• Christina Milian
• Noel Schajris
• Maria José
• Jesse McCartney
• Bridgit Mendler
• Ashanti
• Luis Fonsi
• La Oreja de Van Gogh
• Michelle Williams
• Lindsay Lohan

Gender-skewed Genres

By looking at the genres of the most gender skewed artists we can also get a sense of which genres are most gender skewed as well.  Looking at the genres of the top 1000 artists listened to by male listeners and the top 1000 artists with female listeners we identify the most skewed genres:

Genres most skewed to female listeners:

• Pop
• Dance Pop
• Contemporary  Hit Radio
• Urban Contemporary
• R&B
• Hot Adult Contemporary
• Latin Pop
• Teen Pop
• Neo soul
• Latin
• Pop rock
• Contemporary country

Genres most skewed to male listeners:

• Rock
• Hip Hop
• House
• Album Rock
• Rap
• Pop Rap
• Indie Rock
• Funk Rock
• Gangster Rap
• Electro house
• Classic rock
• Nu metal

Summary

This study confirms what we expected – that there are differences in gender listening. For mainstream listening about 30% of the artists in a typical male’s listening rotation won’t be found in a typical female listening rotation and vice versa. If we happen to know a listener’s gender and nothing else, we can improve their listening experience somewhat by replacing artists that skew to the opposite gender with more neutral artists.  We can even improve the listening experience for a listener that we know absolutely nothing about – not even their gender – by replacing gender-polarized artists with artists that are more accepted by both genders.

Of course when we talk about gender differences in listening, we are talking about probabilities and statistics averaged over a large number of people. Yes, the typical One Direction fan is female, but that doesn’t mean that all One Direction fans are female.  We can use gender to help us improve the listening experience for a brand new user, even if we don’t know the gender of that new user. But I suspect the benefits of using gender for music scheduling is limited to helping with the cold start problem. After a new user has listened to a dozen or so songs, we’ll have a much richer picture of the type of music they listen to – and we may discover that the new male listener really does like to listen to One Direction and Justin Bieber and that new female listener is a big classic rock fan that especially likes Jimi Hendrix.

update – 2/13 – commenter AW suggested that the word ‘bias’ was too loaded a term. I agree and have changed the post replacing ‘bias’ with ‘difference’