Founded by Dr. Fritz Sennheiser just a few weeks after the end of the Second World War to build test and measurement equipment, Sennheiser became a manufacturer of microphones when the Siemens Corporation came to them looking for a supplier for an existing microphone, the DM 1. Discovering a new market, Sennheiser developed a new mic, the DM 2, which they successfully brought to market in 1947. Shortly thereafter, they released the DM 4, the first noise-compensating microphone, which quickly became a favorite of hucksters and sales booth announcers. It was also durable enough that it became known as the "Bug Hammer," after it was used to kill insects that were bothering the announcer, then immediately returned to its intended purpose, none the worse for wear.
They were also innovators in headphone design, releasing the first open headphones, the HD 414, in 1968. The HD 414 could be said to have created the modern headphone market, as the open design vastly improved both the sound and comfort experience for the listener. Sennheiser has followed through with continued innovation in mics, headphones and especially in the field of wireless, which they had pioneered in the '50s. The acquisition of Georg Neumann GmbH, manufacturer of studio condenser mics of the highest quality, rounded out the Sennheiser family of products, adding a further shine to the company's sterling reputation.
This reputation for innovative design and durable construction expanded their market. Dr. Sennheiser was enthusiastic in his support of developing new technologies in-house and not resting on their laurels, as the company began to develop power amplifiers and mixers to complement their mics. They continued with a number of firsts—the first interference tube microphone for film and television and the first wireless mic, the Mikroport in 1957, and the classic MD 421 dynamic mic, released in 1960, remains a favorite of both studio and live sound engineers today.