It's 15 seconds because the song uses a four bar chord progression. 4 bars * 4 beats per bar = 16 beats. The song is around 64 bpm so you do the math and it c

It's 15 seconds because the song uses a four bar chord progression. 4 bars * 4 beats per bar = 16 beats. The song is around 64 bpm so you do the math and it comes out to 15 seconds