Recording and Voice Processing, Volume 1

3Microphones

Today, most of us carry a microphone without really knowing it. Our smartphones necessarily incorporate one of these devices, and it should be noted that the advent of the telephone was fundamental in the invention and evolution of the microphone. By metonymy, the piezoelectric and electromagnetic transducers are also called microphones.

We could start by asking ourselves why we chose the term microphone to designate this device. It can be broken down into two parts from the Greek (mikros), the affix “micro”, which means small, and the word “phone” (fôné), which means sound or noise. Microphone can, therefore, be translated as “small sound”, which is not without meaning, since this device is intended to process small sound signals.

The role of a microphone is to transform mechanical energy, sound, into electrical energy, an audio signal.

3.1. A little history

The term microphone was first used by the English physicist, Sir Charles Wheatstone¹.

He was one of the first physicists to understand that sound is transmitted via waves that travel through a gaseous, liquid or solid medium and to create devices capable of amplifying sound to transmit it from one place to another.

Figure 3.1. Sir Charles Wheatstone

In 1861, Johann Philipp Reis² designed a device that converts a sound into an electrical signal that can be transmitted via an electrical wire to a second device, ...