The objective of the book is to focus insights in the field of Acoustics of Musical Instruments, Room-Acoustics and Psycho-Acoustics on applications in musical performance. In this context, the directional dependence of sound radiation by musical instruments and the voice, as well as questions of concert hall design and room acoustical computer simulations and seating arrangements within the orchestra, or the positioning of microphones is a central issue. The presentation dispenses with mathematical details and prefers conceptual explanations and pictorial representations in order to make the interpretation of acoustical processes accessible to musicians. In this context the pictorial representations of directional characteristics are of particular interest. This translation corresponds to the latest (fifth) German edition (2004). Questions of orchestral arrangements have been revised. Since the first edition was published in 1978, this book has been completely revised and rewritten to include current research. This book is based largely on the Author own research as well as decades of teaching experience in the field of audio engineering (Tonmeister). Noteworthy are also orchestral demonstrations both as conductor and presenter.