The year was 1924 when Dr. Walter H. Schottky and Erwin Gerlach co-invented the ribbon microphone. The design was made up of a very fine ribbon suspended in a magnetic field that could generate electric signals.
In the early 30s, along came Harry F. Olson, a pioneer in acoustic engineering, and his colleague Richard W. Carlisle both from RCA Victor Company in New Jersey and did some ground-breaking work with the Ribbon microphone. (See Reference 1).
In 1934, Olson and Carlisle developed the Lapel Microphone based upon the ribbon technology that Schottky and Gerlach defined. The microphone had unique conditions that had to be met in order to be a viable solution. It needed a broad bandwidth that could be compensated for the diffraction of the human voice about the head of the person speaking (This was solved by compensating for the diffraction via a calculation of it). The output needed to stay level even when the person’s head moved from side to side (Easy—use the velocity principle. Make the microphone construction so that its output would be proportional to sound pressure and not wave velocity). A good sensitivity and a lightweight construction was a must to make it transparent and not cumbersome to the user wearing it.
The frequency response was a pretty flat +/- 2 dB over 80 Hz to 7kHz (See Figure 1) while being only 1/40th the volume of a standard microphone design.
A is the output of a Velocity Microphone on a lapel, being tested with an artificial voice in the position that would normally be occupied by the human voice. B is the ration of the Lapel Velocity Microphone output, being tested in front of the artificial voice, to the ideal characteristic of a Lapel Microphone in Velocity operation. C is the same curve as seen in A without correction for artificial voice spatial characteristics. (0 dB = 1V/bar open circuit emf in a 250 ohm line) (Image courtesy of Reference 1)
Now we move forward 74 years from the Ribbon Microphone invention to Royer Labs which has re-energized the life of the Ribbon Microphone with a new patented design renovation.
Finally, we move on to The Technology and Beauty balance in the creation of a product and the iPhone where Knowles wins microphone slots in iPhone 6S.
Where we go next in this journey is anyone’s guess. What do you think?
1 A LAPEL MICROPHONE OF THE VELOCITY TYPE* BY HARRY F. OLSON AND RICHARD W. CARLISLE, (RCA Victor Company, Inc., Camden, New Jersey), Proceedings of the Institute of Radio Engineers, Vol.22, Number 12, December 1934.