The SPEAKER and / or even the ACOUSTIC DIFFUSER (generally meant a set of loudspeakers each entrusted with a specific frequency range) is an actuator that converts an electrical signal into sound waves. It can therefore be generically defined as an "electroacoustic" transducer. In the Audio chain of a sound reproduction system (Hi-Fi or better), this device is the last link; the next stage is our auricles, our acoustic perception.
The sound, in essence, is generated by a series of compressions and rarefactions of the air. In a nutshell, the speaker's task is to generate such compressions and rarefactions in the listening environment. There are many types of Loudspeakers such as: Magnetodynamic, Electrodynamic, Electrostatic, Piezoelectric, Plasma. In turn these can work in various configurations such as: free field, open panel, closed case or pneumatic suspension, low reflex and, finally, horn loaded. Finally, in modern times, a further distinction has been made, namely: "active or amplified", that is, the amplifier module is also contained within the speaker or "passive" which is nothing more than the single link of the Audio chain of referred to above.
