Blue Days Black Night

FREEDY JOHNSTON Blue Days Black Night (Elektra) Sometimes a clear, quiet voice can be more moving than even the most passionate belting. And sometimes it's just boring. Johnston's toothless vocals have always fallen somewhere in between, and his tastefully tame fifth album is no exception. Paired with a distinctive melody (''Changed Your Mind,'' ''Until the Sun Comes Back Again''), his unobtrusive croon is subtly effective. But on too many of these songs, he just shrinks into the background, offering little reason to pay attention. B