Car Audio Glossary

Car Audio Glossary

New to car audio and not sure of all the terminology? Fear not, check out this Car Audio Glossary for a full and simplified explanation of all terminology and car audio parts.

Whether it’s the physical car audio equipment or terminology associated with audio science, you will find it below.

Car Audio Glossary


Acoustic Energy

Energy consisting of fluctuating waves of pressure that passes through matter in the form of a wave. It’s what we commonly call soundwaves.

Acoustic Suspension Enclosure

A speaker enclosure in which the box is sealed and has no vents. Acoustic suspension systems are known to reduce bass distortion that can be caused by stiff motor suspensions. It does this by utilizing the trapped air inside the enclosure to assist the suspension of the speaker.

Amperes (A)

Measurement in units for Current, which is shortened as ‘amps’. Amperes are used to express flow rate of electric charge. For any point experiencing a current, if the number of charged particles passing through it is increased, the Amperes of current at that point will increase.


Colloquially called ‘amp’, it’s an electronic device that can increase the power of an electrical signal to your loudspeakers, and help them produce louder and clearer high fidelity.


Is the verb used to mean an increase in signal level, amplitude, or magnitude. In other words, crank up the volume.

Amp Wiring Kit

An all-in-one wiring kit that contains all the essential things you need for connecting your amplifier to your stereo system.


An electrical signal in a format of continuous vibrations that are analogous to the original soundwaves. Before music became digital, it was analog and this captured the continuous wave of the analog signal, which basically means what they hear is what they record.


A hi-fi enthusiast who is fascinated by pure audio, motivated by sound quality and generally has a high interest in audio gadgets. Audiophiles usually take their passion for music one step further, and are maybe curious about how songs are recorded and the science behind how sounds are reproduced.

Audio Signal

An electrical representation of a sound wave in the form of alternating current (A/C) or voltage. Audio signals have frequencies in the frequency range from 20 to 20,000 Hz, which is the lower and upper limits of human hearing.


Bandpass Enclosure

A sealed enclosure with an acoustical filter in front of it that helps limit the high-end of the driver’s frequency response. The name ‘bandpass’ gives it away really, as it refers to the fact that the enclosure will only allow a certain frequency ‘band’ to ‘pass’ through.

Bandpass Filter

An electronic device or circuit which incorporates both high-pass and low-pass filters in order to limit and attenuate both ends of the frequency range.


Refers to the range of frequencies that audio/data can be passed through to transmit a signal.


The low audio frequency output. The bass frequency range extends up to around 400Hz, although most bass playing usually falls between 40Hz and 200Hz.

Bass Booster

Increases the relative gain of bass by using selective filter circuits to apply more gain to low frequencies. It’s commonly found on amplifiers and Equalizers (EQ), but shouldn’t be overused as it can drown out other frequencies.


The process of combining left and right channels of an amplifier into a single, more powerful L & R mono channel. Bridging is common when using an amplifier for a subwoofer as it allows amplifiers to send out a more powerful signal.



A device that’s used to temporarily store electrical energy. They’re made of a pair of conductive plates that are separated by a dielectric material. They’re an essential element of any powerful car audio speaker system that consumes a lot of energy, and will benefit an amplifier and subwoofer, and ultimately your car’s electrical network.

Car Play

Apple Car Play is a feature in new cars and some aftermarket head units that allows you to synchronise many apps on your iPhone to your head unit. You can’t use every application, but there are many you can use such as GPS navigation, YouTube, Siri and much more.


A complete and closed path around which a circulating electric current can flow.

Circuit Breaker

An electromechanical device designed to quickly break the electrical connection if a short circuit or overload takes place. It’s similar to a fuse, but instead of working on an electrical and thermal properties, a circuit breaker works on the electromagnetism and switching principle. Another key difference is fuses cannot be re-used, whereas circuit breakers can.


A form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. It will cause the amplifier to output power beyond its power rating, and could cause your amp to overheat and also damage your speakers.


A device that takes a single audio input and filters it into 2 or more frequency bands that can be separately routed to different range loudspeakers. There are Active and Passive Crossovers.

Crossover Frequency

The sound frequency that starts the cutoff point for crossover filters. It’s the frequency point at which signals are reduced by 3 decibels (represented as -3dB) between each frequency range.


The flow of free electrons through a conductor and measure in units called amperes (amps).


Direct Current (DC)

A flow of electrons that can travels in one direction only.

Decibel (dB)

A logarithmic unit used to measure the ratio of change in sound level. The decibel (dB) scale is a logarithmic system, as opposed to a linear scale, so going from 1 watt to 2 watts of amplifier power gains 3dB of additional output. And going from 2 watts to 4 watts gains an additional 3dB of output.

Digital Signal Processor (DSP)

A DSP is a device that uses a microcontroller to manipulate audio signals, which optimizes the different tones and frequencies. Pretty much all DSP devices on the market include crossovers, equalizers and signal delay features that we can use to optimize your soundstage.


Refers to size 2″ x 8″ opening that a car radio fits into. DIN stands for Duetsch Industrie Normen, which the Germans starting using to standardize car radio sizes. The size is now known as Single DIN, and newer multimedia stereos are generally Double DIN, which is 4” x 8”.


Sound output that has been deformed from its input. This is usually caused by clipping, harmonic distortion, or intermodulation distortion, which is when signals of different frequencies are mixed together and additional signals are formed, usually caused by

DVC (Dual Voice Coil)

A speaker with two voice coils that allow a single speaker to output both stereo channels through one speaker, creating a stereo sound from a single speaker location. Many subwoofers come with DVC as they also offer more flexibility for wiring.

Dynamic Range

The range difference between the quietest and the loudest passages of some music being played.



Often mistaken with Sensitivity, Efficiency is the measurement of a loudspeaker or amplifier’s ability to convert input power to output power. Basically, it’s used to describe how much power a speaker or amp needs to achieve a desired loudness level.


Usually displayed as EQ, it’s an audio filter that’s either hardware or software that’s and acts to isolates certain frequencies and either boosts them, lowers them, or leaves them unchanged. The most basic type of equalization is the treble/bass control on audio equipment.



The property of sound that most determines pitch. It’s made up of a periodic vibration whose frequency is in the band audible to the average human. The SI unit of frequency is the hertz (Hz).

Frequency Response

Describes the range of frequencies a component can reproduce. Frequency response measures how well a particular audio component reproduces all of these audible frequencies and if it makes any changes to the signal on the way through.



Refers to the amount by which the signal-handling capabilities of an audio system can exceed a designated level. It’s basically the safety zone that allows transient audio peaks to exceed the nominal level without damaging the audio signal or even the device.

Head Unit

Also known as the Car Stereo, Car Radio, and Receiver. It is the device that controls the audio, navigation of your vehicle. As well as controlling audio, they’re used as radio tuners, CD/DVD players, auxiliary inputs, and multimedia players and much more.

Hertz (Hz)

The unit for frequency in cycles per second. Each Hertz is often abbreviated as ‘Hz’, and to represent thousands of Hertz we use kilohertz (kHz). The average human can hear between the range of 50 Hz to 20 kHz.

High Fidelity

Often shortened to Hi-Fi or HiFi, High Fidelity refers to high-quality reproduction of sound with no inaudible noise or distortion, and as close to the original sound as possible.

High Frequency (HF)

Radio frequency and electromagnetic waves between 3-30 Megahertz (MHz). In audio it usually refers to frequencies between 2 kHz and 20 kHz.

High Pass Filter (HPF)

An Equalization tool that passes signals with a frequency higher than a certain cutoff frequency and attenuates signals with frequencies lower than the cutoff frequency.



Imaging is the manipulation of a signal within a 180-degree sound stage, for the purpose of creating a perception of locality within that stage. The different instruments playing from the width and definition of the sound stage should appear to be coming from their correct positions, relative to recording.

Impedance (Audio)

A measurement of the resistance to the audio current by the voice coil of the speaker. Ohm (Ω) is the unit of measure for impedance, and speakers have a typical impedance rating of 2 ohms, 4 ohms, 8 ohms or 16 ohms.

Impedance (Electrical)

The dynamic resistive opposition offered by a device or circuit to the flow of alternating current (AC) after a voltage is applied.


An electrical component that impedance increases as the frequency of the AC increases. Inductors are generally used in passive crossovers and are known as ‘coils’ and they help block higher frequencies without having any effect on lower frequencies.


Refers to sounds or signals where frequencies are below the range a typical human being can discern, generally considered to be 20 Hz.

Isobaric Speakers

A mounting technique where two woofers are used together and operate simultaneously as a single unit. The mounting of the woofers should ensure the air chamber between them is small enough to virtually be incompressible. They are most often used to improve low-end frequency response without increasing cabinet size.



A unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second.


Line Output Converter (LOC)

A device used to convert a speaker-level output signal into an RCA preamp-level signal by decreasing the voltage. They’re often needed for integrating an aftermarket amplifier to a factory head unit with RCA cables.


Any electrical component that is connected to a circuit that consumes electricity.

Low Frequency

Radio frequencies within the 30 – 300 Hz band. In audio it usually refers to frequencies in the 40 – 160 Hz band, and is what we call bass.

Low Pass Filter (LPF)

A network of components which attenuate all frequencies above a set frequency. In other words, low-pass filters help in removing short-term fluctuations, and provide a smoother form of signal for your stereo system.


Midbass Speaker

A loudspeaker specifically designed to reproduce a high-frequency bass which gives more depth to the sound. They’re also great for creating low frequencies. They have a frequency range of 80 Hz to 350 Hz.

Midrange Speaker

A loudspeaker specifically designed to reproduce the frequencies in the middle of the audible bandwidth. The driver is designed for more of a middle-frequency spectrum with a frequency range of 350 Hz to 5 kHz.


Noise Floor

The measure of the signal created from unwanted signals, where noise is defined as any signal other than audio outputs. It is generally measured in decibels (dB).



A halving or doubling of frequency. For example, 80 Hz is one octave higher than 40 Hz, whereas 5 kHz is one octave lower than 10 kHz.

Ohm (Ω)

The unit of measurement for electrical resistance. In audio ohms is the term used to represent the impedance of a speaker, which is basically the resistance of the flow of electricity.

Ohm’s Law

Ohm’s law helps us in determining either voltage, current or impedance or resistance of a linear electric circuit when the other two quantities are known to us. It’s a formula used frequently in car audio installation on both the power input and the power output side.

Where E is voltage measured in volts, I is current measured in amperes (amps) and R is resistance measured in ohms: E=I*R

For example, if you need to work out the current moving through a 12 volt circuit and you know the resistance of the circuit is 4 ohms, the equation would look like this:

E = 12volts
I = unknown
R = 4 ohms
I = E/R or I = 12/4 which is I = 3 amps


Pink Noise

A type of noise that we perceive as being balanced throughout the frequency spectrum, and to our ears, the low frequencies sound as loud as the high frequencies.

Ported Enclosure

Also known as Vented Enclosures, Ported Enclosures have a hole (port) in the front that equalizes pressure between the inside and outside of the speaker. They’re known for being more efficient than other enclosures, but also less accurate results from a reproductive sound perspective.


A circuit unit that takes a small signal and amplifies it so it can be fed into the power amplifier for further amplification. The pre-amp supplies voltage only, not a current. It’s the power amplifier that provides the current, so you cannot have one without the other.



A passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors reduce current flow and lower voltage levels within circuits, and are one of the main noise sources in the amplifiers

RCA Connectors

A type of electrical connector used to carry audio and video signals. The connectors male plug is called RCA plug, and the female is called an RCA jack.


The point at which the attenuation of frequencies starts.


Sealed Enclosure

A speaker enclosure that uses the air trapped inside of a completely sealed box to affect the motion and performance of the speaker. The air inside the enclosure acts as a spring, which helps control the movement of the speaker cone. For example, when the speaker moves out, the pressure inside is decreased, and when the speaker moves in, the pressure inside is increased. Sealed enclosures are known for producing richer sounds at lower octaves, and smoother transient responses compared with ported enclosures.


The rating of a driver that indicates the level of sound intensity the speaker produces at a distance of one meter when it receives one watt of input power. It is measured in decibels (dB).

Signal-to-Noise Ratio (S/N)

The S/N Ratio compares a level of signal power in relation to noise. It is usually expressed in decibels (dB). Higher numbers mean a better specification, because the ‘Signal’ is more useful information than the ‘Noise’ which is unwanted.

Sine Wave

A mathematical curve that describes a smooth repetitive oscillation.

Sound Deadening

Sound insulation treatment you can add to a car or a room that helps soundproof it. Sound Deadening works by dampening the resonance your car creates from all the vibrations and external road noise created while driving.

Sound Processor

A device that connects to your head unit and removes unwanted sounds so the signal sent to your amplifier is clean, resulting in drastic sound improvements.


The pattern of disturbance caused by the movement of energy traveling through a medium, such as air or water as it propagates away from the source.

SPL (Sound Pressure Level)

The measure of the loudness of sound. It’s a logarithmic scale that allows us to represent the sound pressure of a sound relative to a reference pressure. The reference sound pressure is typically the threshold of human hearing.


The accuracy with which a stereo system converts audible information compared with the original recording space and the placement of the artists within it.

Subsonic Filter

Basically a HPF filter for your subwoofers and attenuate frequencies so low that your subwoofer cannot reproduce them or that humans are incapable of hearing.


A loudspeaker made specifically to reproduce low audio frequencies that we call bass and sub-bass, generally below 125 Hz that other speaker types cannot reproduce.


Time Alignment

Time Alignment is a feature that allows you to delay the output of the closest speakers to you so that the acoustics from every speaker reaches your ears at the same time. You can get this feature on good quality Equalizers and Digital Signal Processors.

Total Harmonic Distortion (THD)

A measurement of the harmonic distortion present in a signal. THD is expressed in %, and anything under 1%, most listeners will not hear any distortion. Some musicians and audiophiles, however, may notice that level of distortion.


Also known as a Treble Speaker, a tweeter is small driver meant to reproduce high audio frequencies, typically from around 2 kHz to 20 kHz, which is considered to be the upper limit of human hearing.


Voice Coil

A coil of wire that is attached to the apex of a driver and takes in the electrical energy coming from the amplifier and converts it into acoustical energy or mechanical motion.


Watt (W)

The basic practical unit for measuring electrical power. The Watts of a loudspeaker is the effect that a loudspeaker can withstand under specific conditions.

Watt’s Law

Defines the relationship between power, voltage and current and states that the power in a circuit is a product of the voltage and the current. P=IV

You can use Watt’s law to find or calculate the voltage, power, ampere, and resistance. It can also be combined with Ohm’s Law to get many useful formulas including P=I2R and P=V2/R.


The distance a cycle of sound or electromagnetic wave travels from point to point.

Wiring Harness

A bundled system of wires used to keep many wires or cables organized. The wires are cut to the same length, bundled and clamped to terminal or connector housings to form a single piece. For example, the many small different color wires that we connect to the back of a head unit.

Wire Gauge

The measurement of a wire, either its diameter or cross-sectional area. The gauge of a wire determines how much current can flow through it, and it also determines the resistance of the wire and its weight per unit of length. Wire gauge is usually specified in AWG, with lower numbers being thicker wire.


A loudspeaker that is well suited for reproducing low and midrange frequencies from 50 Hz to 1000 Hz. They’re typically 4-8 inches in diameter when used in car audio applications. Woofers do most of the work in reproducing the frequencies you hear.



The distance a speaker can move while keeping a constant number of voice coil windings inside the magnetic gap of the speaker.


Leave a Comment