Overview
James Edward Maceo West (born 1931) co-invented the electret condenser microphone at Bell Labs with Gerhard Sessler in the early 1960s. By using a permanently charged polymer film instead of an external polarising voltage, they made the condenser microphone cheap, small and robust. It is the element in the overwhelming majority of microphones made since. He holds more than 250 patents.
What You Need
- Born 1931, United States
- Anchor year: 1962 — the electret condenser microphone
- Strand: overlooked — ubiquitous device, unknown name
Steps
The problem as it stood
Condenser microphones sounded excellent and needed a polarising voltage supply, which meant bulk, cost and power. That was acceptable in a studio and impossible for a telephone handset, a hearing aid or a consumer device.
What he actually did
West and Sessler used an electret — a dielectric material carrying a permanently trapped electrical charge, analogous to a permanent magnet — as the diaphragm or backplate. The bias is built into the material, so no external polarising supply is required.
How it worked
A charged polymer film holds its charge for decades. Sound moves the diaphragm, changing capacitance against the backplate, and because the charge is fixed the voltage varies with the spacing. The result is a condenser microphone that needs only a small amplifier, can be made a few millimetres across, and costs pennies.
What it made possible
Microphones in telephones, hearing aids, camcorders, laptops, headsets and eventually every smartphone. Estimates put electret and its MEMS descendants at around ninety per cent of microphones manufactured. Every voice note, video call and podcast recorded on a phone goes through this invention.
What happened to him
West spent forty years at Bell Labs and later became a professor at Johns Hopkins. He has been a prominent advocate for increasing the participation of Black and other underrepresented students in science and engineering, and co-founded programmes to that end.
Where the credit landed
West and Sessler are properly co-credited in the technical literature and almost unknown publicly, which is the standard fate of component inventors at large laboratories. The work is Bell Labs work and the patents were the company's. West being a Black engineer who built a distinguished career at Bell Labs from the 1950s is worth stating plainly, as is the fact that his invention is probably in the device you are reading this on.
Pro Tips
- An electret is to charge what a permanent magnet is to magnetism.
- No polarising supply is what made condensers cheap enough for consumer devices.
- Roughly ninety per cent of microphones made today use this principle.
Knowledge Base
What You'll Learn
The most-manufactured transducer in history, and hardly anyone can name its inventors.
From electret to MEMS
The modern successor is the MEMS microphone, etched from silicon and small enough that phones carry several for beamforming and noise cancellation. Sessler was involved in that development too. The operating principle is unchanged from 1962 — a moving diaphragm varying a capacitance with a built-in bias — but manufacturing moved from assembly to semiconductor fabrication, which is why a phone can contain four of them.
Where This Fits
This guide covers one specific part of the history of media technology. The wider picture — how each link in the chain from capture through transmission to display was actually built, who built it, and why the credit so often landed somewhere else — is in A History of Broadcast Technology: The Chain From Capture to Screen, which frames the discipline as a whole and links out to the detailed guides underneath it, including this one. If you are starting from scratch rather than solving a specific problem, read that first and come back here.
FAQ
Q: What is an electret microphone?
A: A condenser microphone using a material with a permanently trapped electrical charge instead of an external polarising voltage. This makes it small, cheap and low-power, which is why it appears in almost all consumer devices.
Q: Who invented it?
A: James Edward Maceo West and Gerhard Sessler, at Bell Labs in the early 1960s. Both are credited in the technical literature.