Imogen Heap's fourth record is less a coherent album than a collection of crowdsourced collaborations, generated through methods and techniques that include a running app and a pair of gloves that turns the wearer's body into a human harp. Sparks was written in a community garden in Hangzhou, China, and in the Himalayas in Bhutan. There's a song called The Listening Chair that will never be finished, with Heap promising to add a new verse every seven years. If you uploaded images of your footprints to her website, you'll find them reproduced on the cover. (As fan interaction goes, it's definitely one up on a T-shirt.) Musically, Sparks is a bit of a mess. In its dogged determination to be unique, it has sacrificed structure and direction, and it gets bogged down in the sheer volume of all the voices. While it's easy to admire the ambition of this album, it isn't always easy to listen to.