Mobile phone speaker history

Since 1877, the American inventor Thomas Edison invented the roll barrel type phonograph began, entered the mono recordings of the era. By 1958, people were recording and playing audio, still in a single channel. Single channel refers to the audio signal from different directions mixed by the recording device to record it, and then by a speaker playback. The effect of the replay is simple and is distorted relative to the real natural sound. Mobile phone speakers are divided into single channel, dual channel, stereo three parts! In the single track audio equipment, you can only feel the sound, music and the front and back position and tone, volume, and can not feel the sound from the left to the right, and so on. Popular to say that is a two voice channels and electrical signals in the circuit they tend to their own transfer is not the same, electro acoustic experts in pursuit of stereo, due to technical limitations, in the earliest time only by dual channel to achieve, so stereo and dual channel seems to have become a thing.