"Insomniac" by Straight No Chaser

Since I've gone far too long without analyzing an a capella song, I will procede to do that right now. "Insomniac" is probably the best known song performed by IU's a capella group Straight No Chaser. The original is done by Billy Pilgrim, and I don't know who that is either, but enough with the background. This song has three main chord progressions, one for the verses, one for the intro and one for the chorus. We begin with a small descant over the intro riff (I-IV-V, repeated) which we do twice before we introduce our chorus progression. This section is very rhythmic, as the bass pounds out eight notes over the rest of the groups staccato quartes on beats on 1, 3 and 4. We repeat I-I-IV-IV for 3 lines, before we complete the progression on the fourth line, leaning into a half cadence. The third line we add a small descant over (ahhhs) over the lead line. When we hit the chorus, our lead line spilts into two lines, the duo interplaying as the accompanying voices beat out our chorus progression, a repeated vi-IV-ii-V progression, with an extension the second time, reducing the voices down to simply the bass and lead, as we return to a PAC. The intro riff comes back, only once though, as we return to our verse riff, the upper accompany voice now crescendoing through each chord, adding another layer of texture, a smoothness that is suddenly cut short before changing chords and repeating. This effect adds an air of restlessness as we return to the chorus riff. After this chorus riff we return to it again, holding off the PAC until after another chorus, including a doubled length of the extension. We return to another chorus progression, our final one, and the trasitional extension now becomes even longer, building slowly as we add overlapping voices. We finally come to the climax of the song, crashing through to a huge fortissimo and we bring back our original intro riff, only once, and we finally resolve it to a PAC. I love this song because it has all the elements of a really good a capella number. The bass is low and rhythmic, the inner voices outline the chord but offer some interesting lines, and the upper voices sky over everything, arching and swelling in and out. Long live a capella!