After its foundation in 1947, the Third Institute of Physics (Drittes Physikalisches Institut) at the University of Göttingen soon became one of the main centers of acoustics research in Germany, and also in Europe and possibly the world. This advancement was strongly connected with the personalities of Erwin Meyer, the founding director, and his successors, Manfred R. Schroeder and Werner Lauterborn. But also the variety, broad interest and interaction of all research groups at the Institute contributed to a special, cooperative and very fruitful atmosphere at the "Drittes". Here, we very briefly review some scientific topics and important achievements at the Institute until the turn of the millennium, referring to general and physical acoustics, room and concert hall acoustics, underwater sound, and ultrasound and cavitation. The latter subjects are described in more detail to highlight the very early, but partly not well-known, fundamental and seminal works that had been conducted in Göttingen, already paving the way to important applications and actual research until today.