Page 12 - Spring 2009

Fig 16. Scanning Electron Microscope micrograph of Analog Devices microphone
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diaphragm.
Fig. 15. Akustica serpentine mesh diaphragm design.
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recent commercial success of Knowles. It is further fascinating to examine the parallels between the early days of electret con- denser microphone commercialization and what is happening today in MEMS. With Gerhard Sessler’s and Jim West’s back- ground in electret microphones and MEMS and Ray Stata’s contributions to MEMS, converters and amplifiers, the meet- ing at Reeves-Reed arboretum was a unique historical event.
Electret condenser microphones meet micro-electro- mechanical-system microphones
It is very interesting to reflect on the evolution of a tech- nology from the early development phase to ultimate com- mercial success. More interesting is the unique opportunity to witness a discussion between such industry veterans who played a sustained role in creating and developing successful
products that have achieved ubiquity.
Interestingly, their informal discussion began with some
keen observations of the state of consumer electronic devices in the 1960’s. At that time consumer products were mostly items like television sets and radios. Audio tape recorders were just beginning to emerge for the consumer market and most recorders used external microphones to minimize mechanical noise pickup in the microphone from the recorder motor. Sessler and West noted that the electret condenser microphone offered significant potential advantages in terms of small size and vibration sensitivity versus the dynamic microphones that
Condenser Microphones 11