1837 Page used electromagnets to produce sound
1876 Bell and Watson applied for a telephone patent and invented the first practical telephone receiver
1877 The German Siemens proposed Patent for the prototype of the loudspeaker
1878 British physicist Rayleigh published the "Principles of Acoustics"
1890 A. White invented the shoulder-mounted microphone (now the telephone Prototype)
1907 De Frorest invented the triode tube
1911 Lever-type speakers for radios appeared (as shown in Figure 1-6)
1917 E.C. Weute invented the electrostatic microphone
1918 The American Wester Electric Company produced a sound amplification device that combined a telephone receiver and a phonograph horn
1919 A.G. Webster An application of mathematical methods to speaker horn design
1920 Johnson & Johnson issued a patent for radio speakers
1921 Magnavox Company produced horn speakers
1922 Siemens' Glock ( E.Gterlach invented the ribbon electroacoustic transducer
1923 Kellev proposed an open baffle and a sealed box at the back
1924 The American Wester Electric Company produced electromagnetic paper cone speakers ( As shown in Figure 1-7)
1924 A.S. Sykes and Glock invented the electric loudspeaker
1924 Rice and Kellogg in the United States invented the electric microphone< /p>
1925 Hanna and Slperian in the United States discussed the design method of horn speakers
1925 Ribbon speakers appeared (as shown in Figure 1-8)
1926 The electric paper cone speaker was put on the market by Magnavox
1927 The positive seam ring was adopted
1929 Kyle launched the classic speaker