Telephone (Alexander Graham Bell)

Telephone (Alexander Graham Bell)

The device that transmits human voice as electrical signals was invented by Bell in 1876.

Technology

Keywords

telephone, Bell, telephone set, transmitter unit, receiver unit, telephone call, telephone connection, telecommunication, patent, microphone, sound quality, technology

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Scenes

Father of the telephone

Alexander Graham Bell (1847, Edinburgh - 1922, Baddeck) was born in Scotland. His father was a researcher in acoustic phonology (the physical description of speech sounds). The young Bell was mainly home-schooled and self-taught. Initially he worked as a teacher in a private school for the deaf. He was the first to develop a system for the education of the deaf and mute. He moved to the U.S. in 1871, where he became a professor at Boston University. He researched hereditary deafness and worked on constructing hearing aids. The idea of the telephone occurred to him in 1875, further developing his own previous ideas. The theory was put in practice in 1876, when he patented the apparatus. He established his own company a year later, and by the mid-1880s it became a multinational business.

Bell’s telephone

The primitive system developed by Bell consisted of a transmitter, a receiver and the network (wires) between them. Bell’s apparatus had a diaphragm (a membrane) inside, with a permanent magnet attached to it. Sound waves made the diaphragm vibrate, which caused the magnet to vibrate in the coil wrapped around it. This induced electric current in the coil, which was then sent to the receiver unit through the wires. There it magnetized the coil which caused vibration in the diaphragm and generated sound waves.

Although Bell himself experimented with microphones, the real breakthrough was the invention of the carbon-dust microphone in 1878, as this method improved the sound quality significantly.

An ‘improvement in telegraphy’

A telephone is a telecommunications device which transmits human voice in the form of electric signals. Morse’s invention of the telegraph was the first step in developing the telephone, as it was the first device that transmitted electric signals. From the mid-19th century, many scientists and inventors were working on the development of a prototype. Bell was the first to have had his revolutionary invention patented, in 1876. Later the invention conquered the world. Today (with many improvements, of course) the telephone is one of the most basic and best known objects of everyday life.

Bell’s telephone

The primitive system developed by Bell consisted of a transmitter, a receiver and the network (wires) between them. Bell’s apparatus had a diaphragm (a membrane) inside, with a permanent magnet attached to it. Sound waves made the diaphragm vibrate, which caused the magnet to vibrate in the coil wrapped around it. This induced electric current in the coil, which was then sent to the receiver unit through the wires. There it magnetized the coil which caused vibration in the diaphragm and generated sound waves. Although Bell himself experimented with microphones, the real breakthrough was the invention of the carbon-dust microphone in 1878, as this method improved the sound quality significantly.

Narration

Alexander Graham Bell was born in Edinburgh, Scotland. He attended university in Edinburgh and London, later he moved to the U.S. where he became a professor of acoustic phonetics at Boston University. Together with his father, he researched hereditary deafness. He developed a phonetic writing system called ‘Visible Speech,’ used to aid the deaf in learning to speak. Later on, he became interested in developing a device capable of transmitting the human voice. His ideas soon took a visible shape, and he patented his invention in 1876. The device relied on the principles of Morse’s telegraph; it consisted of a transmitter and a receiver, connected by wire.

The transmitter for Bell’s apparatus had a funnel-shaped mouthpiece which directed the sounds of the voice onto the membrane. The sound waves made the diaphragm vibrate, which caused the magnet to vibrate in the coil wrapped around it. This generated electric current in the coil, which was then sent to the receiver unit through the wires. There it magnetized the coil which caused vibration in the diaphragm and generated sound waves. These left the receiver unit in the form of a human voice through an output funnel.

Bell’s apparatus revolutionized telecommunications in a short time. However, it has been a subject of much debate whether the telephone was actually invented by Bell, who was a highly productive inventor. In the early 2000s the United States House of Representatives accepted a declaration in which Antonio Meucci, an Italian engineer who also worked in Bell’s workshop was declared as the inventor of the telephone. It is a fact however, that Bell was the first to have a patent on the revolutionary device.

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