5.1 System:  A designation describing a sound system incorporating 5 channels of sound/ speakers and one subwoofer.
Amp:  The unit of measure used with an electric current.
Amplifier:  An electronic component or device that takes low-level signals and recreates the signal with more power.
Attenuators:  A device that reduces an amplified signal without distortion.
Baffle:  A box-like structure that a speaker is placed into to enhance the bass sound of the speaker.
Bass: The lowest existing frequency range usually below 200 Hz.
Bookshelf Speaker:  A small speaker which is designed to sit on a bookshelf or shelf.
Center Channel:  A third front audio channel that is usually used to enhance the clarity of dialog being heard within a sound system.
Coaxial Speaker:  A type of speaker driver where the high frequency driver (the tweeter) is located inside a low or mid-frequency driver (the woofer).
Crossover:  A component that splits up the frequency depending on ranges and directs them to certain drivers.
Current:  The flow of electricity through a circuit as measured in amps.
dB Decibel:  A logarithmic scale measuring the intensity of the sound pressure level of a noise.
Digital Surround Sound:  See definition for 5.1.
Driver:  The cone-like component of a speaker that pushes back and forth to sound waves.
Dual Voice Coil:  A speaker that accepts both right and left channels into one speaker providing full range sound in a smaller space than two speakers.

Floor Standing Speaker:  A specific type of speaker enclosure with an acceptable level of sound height that stands directly on the floor.
Frequency:  The number of repeating sound cycles in a given period, measured in hertz or kilohertz. Human hearing is usually 20Hz to 20KHz with the lower frequencies representing the bass and higher representing the treble.
Grille:  An aesthetic front plate covering for speakers.
Horn:  An element used to increase sound efficiency by placing the driver at the end of a megaphone-like structure.
Hz (Hertz):  Number of cycles per second of sound waves used to measure frequency.
Impedance: The resistance to the flow of an electrical current as measured in Ohms.
kHz (Kilohertz):  One thousand sound cycles per second.
Magnet:  A component of a speaker that uses electromagnets to create movement of the driver reproducing sound.
Midrange:  The middle band of audio frequencies between 150/200 Hz to between 1,000/2,000 Hz.
Ohm:  A measure of resistance in a circuit to an electric current.
Outdoor Speaker:  A speaker that is weatherproofed.
Power Rating:  The maximum amount of power in watts that an amplifier can put out or a speaker can be driven with.
RMS (Root Mean Square): The average continuous power output an amplifier is capable of producing or a speaker is capable of receiving.

Subwoofer: A type of speaker used to reproduce the lowest portion of the frequency spectrum, usually 80Hz and below.
Sensitivity or SPL: A measure of the sound pressure level measured from a distance of one meter from a speaker when the speaker receives a 2.83-volt signal - -1 watt at 8 ohm.
Shielded: A term relating to specific speakers having their magnetic fields contained as to not harm video displays.
Three-Way Speaker: A speaker system containing three individual drivers covering three frequency bands.
Transformer: An important component of the power supply that pulls electricity from a source and then transforms it into power that can be used in electronic devices.
Tweeter: A speaker driver designed for receiving high frequencies usually above 2,000 Hz.
Two-Way Speaker: A speaker system with two individual drivers covering two frequency bands.
Voice Coil: A tightly wrapped coil of wire attached to a speaker driver's diaphragm and located near the stationary magnet.
Watt: A measurement of power obtained by multiplying current by voltage.
Woofer: A speaker driver that handles low frequency signals.