The same equipment with very important sound system is sound box, sound box is composed by horn unit and box body commonly. The horn unit is used as a sounding part, and the box is used as a supplement to the horn unit to correct the sound. Sound principle of speaker unit is a kind of electrical energy into sound a transformation, when different electron energy to coil, coil produces a kind of energy with magnet magnetic field interaction, paper plates, vibration caused by the interaction because the electron energy at any time change, loudspeaker coil will forward or backward movement, so the speaker paper plates will follow movement, These movements change the density of the air and produce sound.

Acoustic psychological

When a tree fell in the forest, there was a loud noise, but no one was in the original forest, so the sound could not be heard. Does that count as a sound? Sounds must have been made, because when tree trunks and branches touch the ground, they all produce certain sounds that no one hears, but that sound is different to what a human or other animal would hear. So it's called Psychoacoustics.