What device is capable of converting sound waves into electrical signals?

The correct choice is a microphone because this device is specifically designed to convert sound waves, which are mechanical vibrations in the air, into electrical signals. This conversion is achieved through various mechanisms, such as the movement of a diaphragm that cuts through an electromagnetic field in a dynamic microphone, or by the variation of capacitance in a condenser microphone.

Microphones are essential in a variety of applications, including recording, broadcasting, and communication, all of which rely on accurately capturing sound and transforming it into an electrical format for further processing or amplification.

In contrast, a speaker converts electrical signals back into sound waves, an amplifier boosts electrical signals to drive speakers, and a receiver typically processes signals, which may include electrical signals from various sources. Each of these devices plays a different role in the audio system, but only the microphone focuses on translating sound into electrical signals.