Today I will talk about an important, I think has positively invention mà influenced human race, it is the voice thoai.Dien electricity is a tool that is used to transmit and receive audio, the most common is the voice of the people Phone Voice work by converting sound waves into electrical signals and by converting electrical signals into sound waves. Alexander Graham Bell, who was born in Scotland invented. Phone is a very important invention of the 19th century has helped to improve communication between people at a distance. The first telephone exchange links people have telephones together so they can communicate by telephone was conducted in Hartford, Connecticut in 1877 and the first telephone exchanges linking the two cities was conducted in 1883. This exchange of city connections to New York and Boston. To this day, the phone is an indispensable material for human life
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