Percussion has been a pervasive and developing presence in Western music throughout the past century: from the pioneering work of Chávez and Varèse‚ to diversifying of means with Stockhausen and the innovations of Harry Partch. The latter’s concept of percussion is especially relevant to the music of the Glasmusik and Metallmusik ensembles‚ formed by Walter Sons during the 1980s as a fresh approach to improvisation – whether individual or collective – and the evolving of new sound possibilities and playing techniques. Having recorded separately on the Musicaphon label‚ it made sense to bring the ensembles together‚ and the present disc is taken from a performance in Kassel – in which the instruments took on the dual function of sound installation and percussion orchestra. What is evident‚ even on a first hearing‚ is the remarkable variety of tone and dynamics drawn from the instruments‚ as is the sensitivity and imagination audible in the interaction of the ensembles. Given the rigour and purpose with which the nine tracks – which can be heard either as separate pieces or as constituents of a larger work – have been elaborated‚ it might seem invi­dious to highlight certain of them over others. However‚ the contrast between the vibrant ostinato rhythms and sustained sounds of track four‚ and the finely­judged crescendo and echo effects of track 9 exemplify the musical processes at their most resourceful and beguiling (a pity‚ though‚ that the applause was retained at the close). Atmospherically recorded‚ with detailed background notes and a track by track ‘structure’ included as a listening aid‚ this is arelease which ought to find wide appeal among those who value the practical and creative dimension of music­making.