What device converts an AC electrical signal into an acoustical signal?

A loudspeaker is the device that converts an AC electrical signal into an acoustical signal. The way a loudspeaker functions involves taking electrical audio signals, which are typically in alternating current (AC) form, and converting them into sound waves that we can hear. This is achieved through the movement of a diaphragm within the speaker that vibrates in response to the electrical signal, creating sound.

The microphone works in the opposite direction; it converts sound waves (acoustical signals) into electrical signals. An amplifier boosts the strength of an audio signal but does not convert it; it essentially enhances the electrical signal before it reaches a loudspeaker. A receiver, often used in radio and communication systems, may process and convert signals, but it does not directly create sound; it typically demodulates and amplifies signals for output. Thus, the loudspeaker is specifically designed for the function of acoustical signal production from electrical input.