No, it is not harmful. And it is better than baby overhearing mom and dad arguing whose turn it is to get up and attend to the baby. Oh my God.... the low levels of argument that sleeplessness can take us to is unimaginable.
Nope! it worked like magic when mine was an infant. it drowned out other noises, so she didn't get disturbed. We used static from a bedside radio for months for both naps and sleeptimes. Eventually I phased it out by lowering the volume a bit everyday / every alternate day.
