World War II
World War II would see massive changes in what had been a relatively stable technology. In the U.S., the federal government acted as an agent of change, perhaps inadvertantly, by acting as a buyer for new forms of dictation technology.
Dictaphone was the first to change, introducing this long-duration, automatic recorder for the military market around 1944. It used a new medium- still basically a cylinder, but now a thin, flexible vinyl medium that they called a belt.
This operated in several ways. The first was the government and military demand for recording systems for special purposes. Dictaphone Corporation (the company had now renamed itself) introduced a machine, still based on wax cylinders, using electronic amplfiers, electromagnetic cutting-heads, and multiple cylinders to make long-duration recordings via telephone lines. These were employed for various purposes by government agencies, such as providing centralized office dictation systems and radio-monitoring systems.
Secondly, military agencies provided new markets to competitors, who Edison and Dictaphone had successfully staved off for decades. Notable were the Soundscriber Corp. and the Gray Manufacturing Company (their product was called the Audograph). These new entrants abandoned the wax cylinder medium, opting instead for plastic discs made of soft vinyl. Without those early government purchase orders, it is unlikely either company would have succeeded. The third way the government changed the situation was to encourage the production of magnetic recorders, particularly wire recorders.
Armour wire recorder
These recorded onto steel wire or tape and were the predecessors of today's audio and video tape recorders, computer hard drives, and many other technologies. By 1945 when the war ended, Edison and Dictaphone were scrambling to introduce a new line of products to head off what they predicted would be a wave of new competition in the U.S. market.