The 'invisible' invention in 90% of our microphones: How two men changed how the world speaks forever.

In 1962, inventors James West and Gerhard Sessler revolutionized audio technology by patenting the electret microphone. This innovation quickly moved from research labs into the hands of consumers, being widely embraced in various electronic devices. Its compact, cost-effective design propelled the growth of personal tech. Today, electret microphones, renowned for their resilience and audio fidelity, dominate the market, constituting around 90 percent of all microphones produced globally.

In 1962, James West and Gerhard Sessler were granted a patent for a new kind of microphone, a small improvement in electronic engineering. It was compact, inexpensive, and sensitive enough to provide clear sound. Few could have predicted that this simple design would become one of the world's most widespread inventions. Today, according to the National Inventors Hall of Fame, this invention can be found in approximately 90% of the two billion microphones produced every year, quietly powering smartphones, laptops, hearing aids, and smart speakers.

Why microphones needed to change

By the early 1960s, microphones were already standard equipment in telephone lines, broadcasting, and recording studios. However, some of the best-performing microphones on the market were condenser microphones. These were expensive, relatively bulky, and required an external power source to operate, which counted as limitations and made them unsuitable for many everyday consumer products.

Bell Labs began searching for a microphone that would combine high-quality performance with a relatively small, inexpensive design, making mass production possible. Rather than improving existing designs, James West, an acoustical scientist, teamed up with physicist Gerhard Sessler and came up with a solution. Their goal was to create a microphone that was reliable, durable, lightweight, and affordable without sacrificing sound quality.

A different way of capturing sound

The change began with the invention of an electret, a material capable of holding an almost constant electrical charge. West and Sessler devised a microphone using an extremely thin sheet of electret film coated with metal on one side. As sound waves struck the film, it vibrated, producing electrical signals that accurately represented the original sound. Because the electret retained its own electrical charge, the microphone no longer required the large external voltage source used by conventional condenser microphones.

The result was a microphone that combined excellent audio quality and a simple design. It was smaller, lighter, cheaper to manufacture, and reliable enough for mass production. As technology became more advanced, manufacturers realized that electret microphones could be used in almost any product that previously lacked a high-quality microphone. Researchers at the Lemelson-MIT Program noted that the electret microphone's compact size, low production cost, and durability made it possible for them to be used in different products, including telephones, hearing aids, camcorders, tape recorders, etc.

Electret Microphone Amplifier (Image credit: Wikimedia Commons)

From laboratories to daily life

The electret microphone soon moved from the laboratory into commercial products. Its extremely low cost, small size, and good sound quality made it attractive to companies that wanted to install microphones in various devices. The use of the electret microphone extended the use of microphones from recording studios, making it possible to use them in a variety of products people could use in their everyday life. The telephone was one of the first and most successful applications of this type of microphone, but it was not the only one. Other applications included the hearing aid, tape recorder, camera, baby monitor, portable audio devices, and others. As consumer electronic devices were also becoming smaller, the small size of the electret microphone was a great advantage. Its simple construction allowed manufacturers to produce it in high quantities and at the same time keep the quality of the microphone high.

As personal electronics became more common in the years that followed, demand for reliable microphones surged. Many communication and recording devices needed an affordable, compact microphone. The electret microphone met those expectations well.

A simple innovation ignited for decades

Unlike many other devices, it did not become outdated because it continued to deliver high-quality sound at low production cost. Over time, the technology improved, and the device became more efficient, but its basic operating principles remained unchanged. Today, electret microphones are installed in smartphones, laptops, wireless headphones, hearing aids, monitoring systems, smart speakers, and many more.

Modern devices contain more than one microphone for noise cancellation, voice and sound quality improvements, and voice command recognition. Even though technology has advanced significantly since the 1960s, electret microphones remain the basis for many electronic gadgets. Today, around 90 percent of the 2 billion microphones that are produced every year are based on James West and Gerhard Sessler's invention, which was patented in 1962.