I was recently recording a CD for a veteran blues singer, and one of the last sessions involved a duet with a guest vocalist. The instrumental tracks had already been recorded and, as is common in pop music production, the final vocals were being added at the end of the process. The two singers were in the studio – each acoustically isolated but positioned so that they could see each other through a window. As they listened to the instrumental tracks on headphones they traded choruses, each also ad-libbing along with the other's lead vocal. At the end of the song, during the vamp, they traded ad libs by drawing from the lyrics of the previous choruses. All well and good in principle – but the reality was a bit of a mess. The first take had great spirit and enthusiasm, but also a lot of ‘problems’ – the vocalists were stepping on each other's lines (the ad-libbing ‘comments’ obscuring parts of the other singer's chorus melody) and there were a variety of nonsensical passages when a less than apt choice of phrase was used to respond to the sung lyric. The trading in the vamp was equally spirited – and equally flawed.

We made a few more complete takes of the vocals but the flaws remained, and where the singers had been loose and excited on the first take, in the subsequent takes they lacked that spontaneous enthusiasm. In the earlier, tape-based era of record production we would have had to resort to recording each section piece by piece, repeating the performance on each part until a satisfactory take was recorded. Eventually we would have got a performance that had sufficient compositional integrity to bear repeated listening, but it would surely have lacked the genuine excitement of that initial run through. Instead, I simply sent the singers to the lounge (they weren’t interested in the process, only the result) and went about reconstructing that first take by rearranging the parts so that they made musical and lyrical sense. This involved moving and adjusting vocal lines so that they fitted neatly into a call and response kind of duet performance without conflicting with each other.