Per Vilhelm Brüel

Per Vilhelm Brüel was a Danish physicist and engineer who pioneered and made fundamental contributions to the development of the physics of sound and vibration. He also formed and founded the world's largest manufacturer and supplier of sound and vibration measurement equipment, systems and solutions, Brüel & Kjær. Brüel was a close friend of Niels Bohr, and despite danger Brüel traveled from Sweden to Denmark during the German occupation with important documents of Bohr's work. Brüel was fluent in Danish, German, English, Swedish, and spoke French and Italian.