Generally, an enclosure system comprises anumber of loudspeakers configurated eletricallyand acustically, in order they can reproduce the full spectrum of audio frequencies.
For the proper matching between the loudspeakers it is utterly important to know their frequency response.
Good loudspeakers specifications includ a graph of the frequency reponse. The graph shows the maximum deviations form a perfectly flat response, and where the deviations occur.
Many loudspeakers manufacturers measure the frequency response in a room without echoes, as known as an anechoic chamber.
In spite of so many improvement in the electroacustical measurement techniques, the interpretation of the frequency response specifications often is difficult due the number of variable involved.
Over the year the acustical engineers were devoted to create types of loudspeakers which could be able to reproduce as much as possible the full range of the audio frequency spectrum.
Such continuous search for the ideal loudspeaker led to the birth of specific type of loudpeakers as kwown as frequency transducers for reproducing low, mid and high.

A: The low frequency driver and its frequency reponse graph or curve also commonly called as woofer.

B: The midrange, or the mid frequency driver and its frequency response graph or curve

C: The high frequency driver and its frequency response graph or curve also commonly called as tweeter