A vocoder is a device that analyzes speech and synthesizes it for communication purposes. Its name was created by combining the words voice and encoder into one title. The vocoder was created in the 1930s as a tool for use in telecommunications functions. Its main purpose was to code speech for mass transmission. The vocoder’s dual function as a speech analyzer and a voice synthesizer allowed for a more precise method of encrypting sound for radio broadcast.
A vocoder works on the same principles that assist in the creation of human speech. The vocoder works on the principle of producing a sound that is identified as the fundamental frequency, similar to how sound is created by opening and closing the glottis in the vocal cords, then filtering the sound through the nose and throat. The frequency is then filtered to produce a variety of sounds that emphasize the subtle nuances of the fundamental frequency, resulting in clear and concise pitch and tone.
The first vocoders were analog devices with a series of band pass filters that allowed them to transmit on several different radio frequencies. Bell Labs began experimenting with the concept of the voder or vocoder in 1928, and the first patents were filed in 1935. While vocoders were first used for radio transmissions, it was only a matter of time before they were used for private communication as well, particularly secure military communications during World War II.
The use of a vocoder expanded beyond simple radio communications over time. The basic principles behind vocoder technology found value in early developments in the new medium of television, and the movie industry found applications that aided in the production of ancillary products that could be used to promote new releases.
The vocoder made its way into the recording studio with a number of popular artists in the latter half of the twentieth century. Instead of using voice as the primary source of information for the vocoder, musical instruments were used. The vocoder’s technology evolved from analog sound production to more sensitive digital sound production, making it an excellent choice for creating soundtracks for films, television shows, and enhancing live stage performances.