“Idyllic” and “tranquil” are probably two words that get used much too often when discussing a particular type of quiet and measured folk music. But damn it, Shannon Lay’s solo work (she also leads rock group Feels) is undebatably idyllic and tranquil. Her new single, “The Moons Detriment,” has such a pronounced calm to it that it still the choppy waters seen on the above cover art. Each guitar strum and every wisp of string work seems carefully considered, like Lay thought for hours about whether or not they would intrude on the environs. Her voice, which floats somewhere in the Sibylle Baier/Linda Perhacs zone, doesn’t so much seize the song as it gently inhabits it. In fact, gentle is another word that’s perhaps overused but apt for this kind of austere work. Whatever passive descriptor is used, this is work that demands active attention.