The fourth night of “the blinds” – the most exhilarating part of this music competition show – are televised tonight. There are additional nights of the blinds, so many more than there used to be when this series began, because the producers know where the show’s strengths are. And also know that, between the drama and the editing, these early rounds are the best way to showcase not only the singers, but the judges – as, this cycle, new Voice judge John Legend.