Doctor R.R.Vreden engaged in developments in the field of telephony completely by accident.
As the best known acoustic specialist, he conducted numerous studies in an attempt to reproduce the human auditory system. These experiments eventually led to his invention of the original microphone.
In April 1880, he completed production of the first ‘electro-acoustic device (which he called the fonofor). It was basically a highly sensitive microphone (essentially an artificial ear) for which he received privilege (patent pending). This device had the ability to take all sound vibrations, even weak and distant ones (including those that were barely audible to the human ear) and transmit them in an amplified manner to one or more phones simultaneously over any distance. The device worked on a similar principle to that of the human ear.
Two years later, in 1882, R.R.Vreden invented another instrument, which he called the ‘phone-protector’, designed to automatically protect telegraph and telephone equipment from strong currents. Widespread use of this device did not take place but the principle of its operation was subsequently used to create the automatic overcurrent.
From 1884 to 1890 R.R.Vreden received patents for the following: a microphone with a movable closing device contact, the sensitivity of which was not affected by its accessories; an underwater microphone to transmit vibrations through liquids and gases; water microphones; the theater fonofor; home microphone etc.