35.1 Introduction

For more than 2000 years acoustic phenomena have been perceived, and manipulated subjectively. Reference can be made in this context to Marcus Vitrius, the ancient Roman architect who described at this early time the application of acoustic laws in theatrical spaces. But only since the end of the Middle Ages and particularly during the last century has acoustics developed into an independent science.

In the beginning, improvements in acoustics were achieved by changing the acoustic properties of rooms and open spaces. The development of electronics has given rise to modem processing techniques and the simulation of acoustic properties became increasingly possible with the help of electroacoustic tools.

Highlights on the way to a scientifically calculated design:

• Roman/ Greek Times/ Middle Ages - knowledge based on experience and first trial and error reports, e.g., by the Roman Architect Vitruv AD 5.

• Since the 18th century - investigations, e.g., Chladni or in 1875 Lord Rayleigh, Prof. Helmholtz.

• since 1900 - room acoustical basics; Prof. Sabine/United States 1923, radiation of sound; H. Stenzel/ Germany 1930, and H.F. Olson/United States 1947.

• By 1935 - measurement in models and "Auralization" in physical models; Prof. Spand ck M nchen, Prof. Rcichardt Dresden/Germany.

• Since 1965 - computer-model investigations; Prof. Krokstad Trondheim/Norway, afterwards many similar works have been done.

• Since 1995 - Auralization by means of computer models became generally available.

35.2 Variation of Room Acoustic