Changes in the construction of musical instruments have always taken place, some with more radical results than others. This book surveys significant twentieth-century developments of Western orchestral and other acoustic instruments, particularly those that offer new forms of expression to composers and performers. Part One of the book provides an overview of wind, brass, string, keyboard and percussion instruments from c.1840 to the present day, focusing on twentieth-century innovations. Patrick Ozzard-Low considers technical, aesthetic and acoustic aspects of these 'new instruments', especially in relation to contemporary music and the late twentieth-century avant-garde. The complex relationship between music and instrumental technique, instrumental design and technology, and instrument acoustics is discussed. Special attention is paid to the use the development of alternative timbres and tuning systems, and to contemporary debate within acoustic and electroacoustic musical aesthetics. Part Two comprises a catalogue of existing 'new instruments' illustrating significant design innovations and technologies. In addition to illustrating the implications of new instrument technology for composition and performance, this section is a useful reference source for instrument makers, researchers and composers.