This paper is about the early part of the history of the Acoustics in Denmark. It is based on previous anniversary writings, the author’s interviews with Dr. Brüel and his own notes ”Episodes and Results in Acoustics before 1954”. Starting with the invention of the ”Telegraphone” in 1898 and other early acoustical inventions (loudspeakers, sound film, radio production), the paper will concentrate on Dr. Brüel and the company he established in 1942 with Dr. Kjær (B&K). The acoustical instrument development took its early start with the world’s first frequency analyzer with constant relative bandwidth (1940) - where B&K’s iconic light-green front plate was seen for the first time. Some background story for Dr. Brüel’s multifaceted effort in acoustics will be revealed, e.g., his work with the acoustics in the new building for the Danish Radio (1941), his work with sound absorbers and university activities in Sweden during WWII (1942) and the doctoral thesis ”Use of the standing wave-method in Acoustics” (1944). The early groundbreaking instruments from B&K include: The tapping machine (around 1945), the level recorder (after 1943; 1949), the pistonphone (around 1950), the condenser microphones (1950; 1955). Finally, the Danish hearing aid companies and loudspeaker companies will be mentioned.