Even Vashti Bunyan‘s blockbuster collaborations are as understated as a quiet morning walk through nature. Heartleap, the English folk singer’s first album since 2005′s Lookaftering, is due out in the United States on October 7 via DiCristina and a day earlier across the pond via FatCat. She has already shared the gorgeously tranquil “Across the Water,” but much press coverage has focused on the album’s collaborations with two Bunyan disciples, Devendra Banhart and Vetiver‘s Andy Cabic. Now, almost without notice, here the two are, cooing soft backing vocals behind delicate guitar, misty strings and quiet synth on Heartleap‘s “Holy Smoke.” The best descriptions of Bunyan’s songs are sometimes her own titles for them. In this case, she’s singing about her breaths in the cold air, not exclaiming about something astonishing. And yet, boy: holy smokes.