History of carbon, condenser, and ribbon microphones used for sound recording and telephony

My last article, which aroused enormous interest, was on the History of Audio Recording. Thanks to everyone who read it and made it a huge success. This article is not important. We certainly cannot discuss the History of Audio Recording without also discussing the History of the Microphone. Neither can exist without the other. Together, let’s explore the birth and development of this incredible invention.

A microphone is simply a device that captures “waves” in the air created by speech or other noise transmitters and translates those waves into electrical signals. Another way of saying it is to convert acoustic energy into electrical energy. Once sound waves are converted to electrical signals, to be heard again in an acoustic environment, they must be converted back to acoustic power through some type of speaker. It’s amazing to think that with all the technological advances of the last 40 years, we still use this simple process on our stereo, computer, or ipod.

Have you attended a concert recently? The relatively weak signal of a voice or musical instrument is created, transformed into electrical energy by some type of microphone, boosted through a series of power amplifiers, and finally converted back to acoustic energy through loudspeakers. . It’s easy to sit back, enjoy the music, and forget to be thankful for this amazing power that was created in our universe and that we enjoy all day.

Let’s meet some of the visionary people who discovered and developed the universal principles that created a microphone.

Juan Felipe Reis (1834-1874)

This German physicist designed a “sound transmitter” that employed the use of a metal strip resting on a membrane with a metal contact point completing a circuit as the membrane vibrated. His basic belief that as the membrane responded to the rise and fall of acoustic energy and bounced the metal tip up and down more strongly and the amplitude of the electrical current increased, was brilliant. Unfortunately, this initial effort was not developed enough to produce speech that could be understood.

Elisha Gray (1835-1901)

This American inventor would one day become one of the founders of the Western Electric Company. Gray’s design was called the “liquid transmitter”. The “liquid” was an “acid” solution. This was an incredible innovation. He attached a diaphragm to a movable electrically conductive rod that was immersed in the acid solution. Fixed a second rod. With a battery connected, a circuit could be completed between the two rods. Acoustic vibrations traveling through the diaphragm caused the distance between the two rods to vary. The result was that this variation produced corresponding changes in the electrical resistance in the acid cell, changing the current levels. These variations could translate to an audible sound for a week.

Alexander Graham Bell (1847-1922)

Famous for his development of the telephone, he used a device similar to Gray’s to produce the first intelligible speech transmission through his primitive telephone. Most of us have heard of Bell’s famous words to his assistant: “Mr. Watson, come here. I love you.” The true inventor of the telephone, however, became a legal dispute between Bell and Gray. The courts remained neutral regarding their claims due to the general poor quality of these early devices.

David Edward Hughes (1831-1900)

While Bell and Gray fought each other in court, Hughes worked diligently to produce the first working microphone. Already a pioneer and patent holder in the telegraph industry in 1855, he designed a new type of microphone in 1878. It was a completely different design from Bell and Gray’s. It incorporated the use of loosely packed carbon pellets in an enclosed space. When the acoustic pressure varied as they traveled through the diaphragm, the electrical resistance traveling through the carbon granules changed proportionally. The resulting sound was loud and full of distortion, but it was a significant step forward. Since early newspaper reports compared his device to a microscope, “acting to the ear as the microscope does to the eye,” Hughes coined the current name “microphone” for his invention.

Thomas Alba Edison (1847-1931)

Edison took Hughes’ design and made it simple, cheap to manufacture, efficient, and durable. He created a cavity filled with granules or charred anthracite coal packed between two electrodes, one of which was attached to a thin iron diaphragm. Refinements of it became the basis for all telephone transmitters used in most telephones of the last century. Also, Bell Telephone and Bell Laboratories continue to be amazing companies that continue to produce new communication technologies.

With the invention of radio, new broadcast microphones were invented, such as the Ribbon Microphone in 1942. The ribbon microphone originally employed the use of an aluminum ribbon that was placed between two poles of a magnet to generate voltages by electromagnetic induction. Since the sound wave caused the tape to move, the current induced in the tape was proportional to the speed of the particles in the sound wave. Historically, ribbon microphones have been finicky and expensive. Today’s modern materials make today’s ribbon microphones durable enough for loud rock music and stage use.

An incredible step forward in microphone development occurred in 1964. Bell Laboratories researchers James West and Gerhard Sessler created the electroacoustic transducer, an electret microphone. The Electret Microphone was a type of Condenser Microphone that offered higher reliability, higher accuracy, lower cost, and smaller size. It revolutionized the microphone industry with nearly a billion made each year. Also, during the 1970s, dynamic and condenser microphones were developed, allowing for lower sound level sensitivity and clearer sound recording.

Microphones are such an important part of our daily lives these days that we take them for granted. After writing this article, I have decided to put them on my list of things to be grateful for. As a pilot, my safety depends in part on being able to communicate by radio. Guess what I use to talk into my headphones? You guessed it, a microphone!

As for the future, many incredible new innovations are being explored.

1) Laser velocity transducers

2) optical microphones

3) Direct digital output

4) Force Feedback technologies used in conjunction with an optical microphone

You can click the “quality_microphones” link below on my website to see some of the latest microphones.

I hope you have learned some important information about microphones. As innovation continues at a rapid pace, the ones we use today may become a future exhibit at the Smithsonian Institution. Until then, they will remain an invention that takes advantage of a universal principle that improves our lives.

The truth is, the universe is probably filled with billions of amazing things that we haven’t discovered yet. As in the past, present and will be in the future, those who possess the faith and perseverance to access the universal mind are the ones who will discover and share the secrets of the universe with all of us.

Maybe you are that person!

Until next time!

jonathan morgan jenkins