"The infographic is based on the part of my book called 'Rihanna: Track-and-Hook.' It’s the heart of The Song Machine, which is about how pop songwriting has changed over in the last twenty-five years, from a craft into industrialized process," he explains to Billboard.
"This has happened partly as a result of technology — mainly the ability to program songs on the computer, and share them easily over the Internet. Whereas songwriters used to work alone or in pairs, they now work in groups of four or six or more. Songwriting has become more like writing a TV show. But even more fundamentally, the basic method of creating song has changed. It used to be that songs were made by melody and lyric writers working together. Now they are collaborations between producers and top liners. The producer spends hours in the studio working up beats, chord progressions, and instrumentation (electronic, of course) into elaborate sound tapestries, and the top liners come in and sprinkle magic around the room, in the form of hooks — the sugary coating on the sonic doughnuts. The artists then bring the songs to life," Seabrook adds.
See the graphic below: