All About Horn Loudspeakers
One of the oldest forms of loudspeakers are the horn loudspeakers that not only provide pure, high efficient, natural music but also fast and accurate transient response.
Basically what happens in the horn loudspeakers is that the diaphragm that is run by an electromagnet is supported by a horn, which improves the coupling efficiency between the speaker driver and the air. However, the horn is like an acoustic transformer that usually gives impedance matching between the diaphragm material and the air, having a low density. This will show the difference in density and motion of the air and of the driving element.