Liz Phair’s voice is thin and dry, perfectly suited to the conversational tone of her 1993 indie-rock masterpiece, Exile in Guyville, but nowhere near muscular enough for the belters she’s trying to write these days. It’s weird to hear such a brilliant mumbler turn into such a mediocre singer — and work so hard at it. On Somebody’s Miracle, she goes for a folksy, acoustic style, but she still oversings, holding notes too long and tackling pop choruses she doesn’t have half the voice for. As on her last couple of albums, the lyrics are sitcom-ready romantic scenarios (“Leap of Innocence,” “Table for One”) burdened by plain and forgettable music: a classic case of inspired amateur become bored pro. Maybe Phair will loosen up and make another album as fluent as Exile or Whip-Smart; more likely she’ll move on to screenplays.