Album: St Petersburg Chamber Choir, Tranquillity: Voices of Deep Calm (Decca)

After the success of various monks', priests' and nuns' albums, and the growing popularity of choral groups like Tenebrae, it was only a matter of time before the liturgical solemnity of Russian Orthodox choir singing became packaged for a broader audience.

Its profoundly calm, soothing character is apparent from the opening version of Rachmaninov's "We Praise Thee", with its seemingly wordless vocal drones – an impression sustained through subsequent material by less renowned writers such as Kalinnikov and Tchesnokov. The most recent piece here is "De Profundis" by Paul Mealor, notable for including the lowest notes ever written for a choral arrangement, an extraordinary subterranean vibration of fundamental impact.