On Ghosts, a variety of keyboards—acoustic piano, electric Fender Rhodes, synths—make up the core of Polish composer, pianist, and singer Hania Rani's sound world. It's an ambient place inflected with delicate melancholia and, occasionally, uplift. A third of the tracks are instrumentals, but rather than simply functioning as musical interludes, the voiceless pieces are an integral part of the album's flow. The hypnotic, slightly ominous instrumental "Oltre Terra" opens the album with carefully crafted pulses, pings, and drones. The piece nicely sets up the incredibly catchy "Hello," where Rani, shaded by backup vocals and jazzy keyboard, gives voice to an irresistible melody that rides rubbery electronic bass and brushed drums. "Don't Break My Heart" hints at gospel and rhythm and blues. Special guest Duncan Bellamy of the British rock band Portico Quartet provides spare and subtle percussion and loops that play off Rani's yearning voice. On "Dancing with Ghosts," Rani is joined by Patrick Watson on vocals and piano; accompanied by a panoply of electronic sounds, their voices mesmerize. The next cut, the gently propulsive "A Day in Never," employs hand percussion and rippling piano to support Rani's rhythmically insistent singing. Icelandic multi-instrumentalist Ólafur Arnalds appears on "Whispering House," where tense breathing and spare and lovely keyboard tones fill the air. The effect is spooky: a haunting of a song that is barely there at all. By contrast, "Thin Line" vibrates with psychedelic energy. Strings arranged by Viktor Orri Árnason wend their way over percolating rhythms as Rani's vocals play with a handful of notes and words. The hypnotic track has a gentle quality but in this dreamy context it qualifies as a rocker.