Enter the maze

The colour of music

a mobile phone with a rainbow emerging from the screen

Music is all about emotion. From a slushy love ballad to the head-banging, no nonsense roller coaster of thrash metal, the songs we listen to can make or change our mood. We have favourite tracks to play when we need cheering up, even maybe some music that keeps melancholic company with us when we are lost in thought. Emotions are what it’s all about, and with portable music players built into many of today’s mobile phones we can listen to music whenever and wherever we want. So how do you ensure that the music you are listing to is right for the mood you are in? Of course you have playlists, lists of your favourite songs, which you can flick through to find the right song for the right mood, but is there a better way? This is the question Queen Mary computer science student Daniel Fiegenschuh asked, and his answer was a smart and colourful one.

a hand playing an electric guitar, bathed in red light

I’m in the mood for some colours

Dan realised that we tend to associate particular colours with particular emotions. Red, for example, might be associated with feeling angry, blue when you are feeling chilled, yellow when you are feeling happy, and so on. We each tend to give colours an emotional ‘tag’. That is, we associate them with a mood. Of course we all tag colours differently. Red might be a colour that makes you feel happy, and blue makes you feel sad. It’s something very personal. So Dan decided to write some software to let people tag their favourite songs with a colour. For example, your chill-out songs might all be green. That’s an emotional association that works for you. Dan’s software, which works on a mobile phone, creates a picture filled with clouds of the different colours you chose that are important to you, and lets you automatically create a playlist of tunes depending on your mood. You move the cursor over, say, the green cloud, click and you create a playlist of the songs you tagged as green. The software comes up with the playlist, so you’ll maybe have some surprise tracks in there. Unlike a playlist you created yourself, the system chooses colour-tagged songs near the point you selected.

Phone a friend

Dan tested to see that his system was easy to use by giving it to his mates to try out for real over several days. He then asked them what they thought of it. This process is called user evaluation and all software should go through this to check it's easy to use, and does what it’s supposed to (though in a professional setting it wouldn’t just be your mates who tested it of course).

The feedback was that they liked it, it was easy to use and also looked cool, but they didn’t like the idea of having to tag all their tracks by hand (too much hassle). They also thought that sometimes a track was in the wrong colour cloud. It wasn’t such a red track after all. There were several times that they skipped tracks in the playlist because of that. Armed with these comments Dan took the project to the next level, and in came some artificial intelligence to make the phone smart.

a person playing the trumpet, silhouetted against a blue background

Clever colours

Dan used a simple computer learning technique called negative selection to add some smartness to the phone. When people skipped a track or just played a little of it, the tune was obviously in the wrong colour cloud. So the duff tracks now start to move round on the screen. They get chucked out of, say, the green cloud as they are negatively selected (skipped) and have to find another better cloud to join. The distance they are moved depends on how long they were played for; shorter plays get them chucked further away from the original colour cloud centre. This way the tracks that aren’t green end up in a different colour cloud. After playing with the system for a bit Dan’s friends found that the artificial intelligence had moved any wrongly tagged tracks into the right colour clouds.


This negative selection idea also meant that any tracks you hadn’t tagged to start with could be tagged with a random colour and then would rattle around through different clouds, like a ball in a pinball machine, till they settled in the right place. The artificial intelligence had solved the problem of automatic tagging of songs and also correcting the tagging of songs in one go. Result! His mates agreed the new system worked and after a bit it was generating exciting mood-enhancing playlists for them whenever they wanted. Maybe one day soon Dan’s smart colour cloud software will float onto your phone. When it does let’s hope it’s a yellow day: a happy day that is.