Audio devices are electronic devices designed to capture, produce, and/or process sound. Popular examples of audio devices include microphones, speakers, amplifiers, receivers, and recorders. Microphones are used to capture sound waves which are then amplified, filtered, and processed. Speakers are the most familiar type of audio device and they produce sound by converting electrical signals into audible sound. Amplifiers take a weaker signal and increase its strength to produce higher sound levels, while receivers are designed to receive and process radio signals. Finally, recorders are used to store audio for playback.