The correct answer is Microphone.Microphone: Converts a sound wave into an electrical signal. The basic use of a microphone is best explained with the help of the following diagram:Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, radio, and television broadcasting.They are also used in computers for recording voice, speech recognition, VoIP, and for non-acoustic purposes such as ultrasonic sensors or knock sensors.Additional InformationA stylus (or stylus pen) is a small pen-shaped instrument that is used to input commands to a computer screen, mobile device, or graphics tablet. Speakers are one of the most common output devices used with computer systems..Speakers are transducers that convert electromagnetic waves into sound waves.A digital camera uses digital optical components to register the intensity and color of light and converts it into pixel data.