What device is used to convert sound waves into an audio signal?

A microphone is the device specifically designed to convert sound waves into an audio signal. It operates by using a diaphragm that vibrates in response to sound waves. These vibrations create electrical signals that correspond to the sound, which can then be amplified, recorded, or transmitted. This process is fundamental to various applications, such as recording music, broadcasting audio, and communication technologies.

Speakers, on the other hand, work in reverse by converting audio signals back into sound waves. Transmitters are typically used to send audio signals over distances, and amplifiers increase the strength of audio signals but do not convert sound waves into signals themselves. Understanding the distinct roles of these devices helps clarify why the microphone is the correct answer in this context.