A few years ago, Keane caused a hullaballoo by forgoing the use of guitar on their pop-rock ponderings. Shunning an instrument that most bands build their sound around was an interesting manoeuvre - but Naturally 7 have gone one better, and don't use any instruments to create music. To be slightly more accurate, the seven-piece vocal group somehow use their voices to create the sound of a full band.

They may be a new name in this part of the world, but the New Yorkers have already had huge success in Central Europe, scoring hits with their Boyz II Men-styled R 'n' B hits, and covers of songs like Phil Collins's 'In the Air Tonight' in Germany, Switzerland, Poland and beyond. 'Wall of Sound' takes tracks from their first three studio albums in a bid to launch them in this corner of the continent - but occasionally impressive as their vocal gimmick is, there's nothing in this collection to really sink your teeth into.

Naturally 7 are undoubtedly talented singers; their beatboxing skills, smoother-than-a-baby's-bum harmonies, and tight arrangements of songs like Mr. Mister's 'Broken Wings', Extreme's 'More Than Words' and Simon & Garfunkel's 'Bridge Over Troubled Water' are all effective, if not completely predictable. The schmaltz element overrides the swoon factor one too many times to be forgiven, however - rendering the whole affair irrepairably boring after just five or six tracks, even despite their instrument-less strategy.

If you like your R 'n' B laced with pop and soul, and delivered with enough sheen to dazzle Stevie Wonder, you'll love Naturally 7. For casual onlookers, though, this is simply predictable balladry hiding behind a silky subterfuge.