An audio component is a device used to process sound. A WOOFER is a loudspeaker designed to produce low-pitched audio frequencies. STEREO is a type of sound reproduction in which two or more independent audio channels are reproduced through two or more speakers. A TUNER is an electronic device that receives radio signals and converts them into audio signals. An EAR is a device used to listen to sound. VIDEO is a type of electronic signal used to transmit moving images. ECHO is a sound effect produced by the reflection of sound waves off a surface. A preamp is an electronic amplifier used to increase the strength of a weak signal before it is sent to a power amplifier.