Audio/Video Terms and Definitions

Audio/Video Terms and Definitions

By: CE Critic

Whether you're a home theater enthusiast, an audiophile, or simply someone who wants to understand the technical side of your headphones, navigating the world of audio and video can involve a lot of jargon. This list compiles the most common terms you'll encounter in A/V, Hi-Fi, and headphone audio, helping you demystify the specs and features you see advertised. 

Audio Terms

  • Amplitude: The intensity or loudness of a sound wave, often measured in decibels (dB). Amplitude in sound wave

  • Bit Depth: The number of bits used to represent each sample of audio in digital audio. Higher bit depth means greater dynamic range and finer detail.

  • Clipping: Distortion that occurs when an audio signal exceeds the maximum level that a system can handle.

  • Compression: The process of reducing the dynamic range of an audio signal, making loud sounds quieter and/or quiet sounds louder.

  • Decibel (dB): A unit for measuring the relative loudness of sound.

  • Distortion: Any unwanted alteration of an audio signal.

  • Dynamic Range: The difference between the loudest and quietest parts of an audio signal.

  • Equalization (EQ):The process of adjusting the balance of different frequencies in an audio signal.

  • Feedback: A high-pitched squealing sound that occurs when a microphone picks up sound from the speakers and amplifies it, creating a loop.

  • Frequency: The number of cycles a sound wave completes in one second, measured in Hertz (Hz). Frequency determines the pitch of a sound.

  • Frequency Response: The range of frequencies that an audio device can reproduce accurately.

  • Gain: The amount of amplification applied to an audio signal.

  • Hertz (Hz): The unit of measurement for frequency (one cycle per second).

  • Mix: The process of combining and balancing multiple audio tracks into a final stereo or multi-channel output.

  • Noise: Unwanted sound that interferes with an audio signal.

  • Panning: The placement of a sound in the left-right stereo field.

  • Reverb:Echoes created when sound reflects off surfaces in a space.

  • Signal-to-Noise Ratio (SNR): The ratio between the strength of a desired audio signal and the level of background noise.

  • Sound Pressure Level (SPL): Measurement of the intensity of sound, in decibels.

  • Waveform:A visual representation of an audio signal.

  • ARC (Audio Return Channel): A feature of HDMI that allows audio signals to travel back up the HDMI cable from a TV to a soundbar or receiver. This simplifies audio connections.

  • eARC (Enhanced Audio Return Channel): An updated version of ARC included in newer HDMI specifications (HDMI 2.1). eARC supports higher bandwidth audio formats like Dolby Atmos and DTS:X.

  • DAC (Digital-to-Analog Converter): A chip that converts digital audio signals (like those from a computer or streaming device) into analog signals that can be amplified and played through speakers.

  • ADC (Analog-to-Digital Converter): The opposite of a DAC, it converts analog audio signals (like from a microphone) into digital form for recording or processing.

  • Speaker Wire: Specialized cables that connect your amplifier or receiver to your speakers.

  • XLR: A type of connector with three pins, commonly used for balanced audio connections.

  • RCA: A type of connector, often color-coded red and white, found on most consumer audio equipment for unbalanced connections.

  • 12v Trigger: A control signal that allows one component to automatically turn on/off another component. For example, a receiver could trigger a power amplifier when it's switched on.

  • Standing Wave: Standing waves are a phenomenon where sound waves within an enclosed space reflect and interfere with each other. These reflections can create areas of high pressure (loud) and low pressure (quiet), resulting in uneven frequency response and muddy sound. Standing waves are caused by the dimensions of your room. They are most problematic with low-frequency sounds (bass), making some notes boom unnaturally while others seem weak. Proper speaker and subwoofer placement, along with acoustic treatments, can mitigate these issues.

  • Phase Alignment: Refers to the timing relationship between sound waves from different sources. When two or more sound waves are "in phase," their peaks and troughs align, resulting in a stronger combined signal. If they are "out of phase," they partially cancel each other out, leading to a weaker, less clear sound. Phase alignment is crucial when you have multiple speakers, especially a subwoofer paired with main speakers. A misaligned subwoofer can make your bass sound muddy or weak.

  • Phase Switch: A simple switch (often 0 or 180 degrees) found on some subwoofers and audio equipment to adjust the phase relationship. The phase switch is a tool for tweaking the alignment between a subwoofer and your main speakers to achieve the optimal bass response in your room.

  • Low-pass Filter: An electronic circuit that allows low-frequency signals to pass through while blocking or reducing higher frequencies. Used in subwoofers to ensure only deep bass frequencies are reproduced, preventing unwanted midrange and high frequencies from muddying the sound.

  • High-pass Filter: An electronic circuit that allows high-frequency signals to pass through, while blocking or reducing lower frequencies. Often used in main speakers to prevent them from trying to reproduce very low bass notes that they aren't designed to handle. This improves their clarity and efficiency.

  • Crossover: An electronic circuit that divides an audio signal into different frequency bands (e.g., low, mid, high).

  • Bass Traps: Acoustic panels designed to absorb low-frequency sound energy, minimizing the effect of standing waves and improving bass clarity. Bass traps are placed in corners or along walls to control the excessive buildup of low frequencies and create a more balanced sound in a room.

  • DSP (Digital Signal Processor): A specialized microchip that manipulates audio signals digitally. DSPs can perform tasks such as equalization, room correction, crossover management, and more. DSPs are used in some subwoofers and AV receivers to fine-tune the sound and automatically correct for acoustic problems in the room.

  • Transducer: A device that converts one form of energy into another. In audio, transducers convert electrical signals into sound waves (speakers) or sound waves into electrical signals (microphones). In multi-way speakers, crossovers send the correct frequencies to the woofer, midrange driver, and tweeter. In a subwoofer system, the crossover manages the frequency split between the main speakers and the subwoofer.

Video Terms

  • Aspect Ratio:The ratio of the width of a video image to its height. Common aspect ratios include 4:3 (standard definition) and 16:9 (widescreen).

  • Bitrate: The amount of data used to represent a video signal per second, usually measured in kilobits per second (kbps) or megabits per second (Mbps). Higher bitrate usually translates to better image quality.

  • Codec: Short for "coder-decoder." A software or hardware device that compresses and decompresses digital video.

  • Color Depth: The number of bits used to represent the color of each pixel in a digital image.

  • Contrast Ratio: The difference between the brightest white and darkest black that a display can produce.

  • Frame Rate: The number of individual frames or still images displayed per second, measured in frames per second (fps).

  • HDMI:(High-Definition Multimedia Interface) A digital interface for transmitting both audio and video signals.

  • Interlacing: A technique where alternating lines of a video image are scanned in separate passes, used in older television standards.

  • Pixel:Short for "picture element." The smallest individual point of a digital image.

  • Progressive Scan: A scanning method where all lines in a video frame are displayed in a single pass, common in modern displays.

  • ABL (Average Brightness Limiter): A feature in some displays (especially OLED) that limits the overall average brightness of the screen. This is meant to protect the display from potential damage caused by prolonged display of high-brightness images.

  • OLED (Organic Light-Emitting Diode): A display technology where each individual pixel is made up of an organic material that emits its own light. This provides incredibly deep blacks, excellent contrast, and vivid colors.

  • APL (Average Picture Level): The average brightness level of a particular image or video frame. ABL systems on displays often take this into account when adjusting brightness.

  • HDR (High Dynamic Range): A standard for image and video content that offers a wider range of brightness and contrast compared to traditional content (SDR). HDR delivers a more realistic and immersive viewing experience with brighter highlights and deeper shadows.

  • WCG (Wide Color Gamut): A range of colors that can be represented, wider than the traditional color standard (sRGB). HDR content often takes advantage of WCG to create images with more vibrant, lifelike colors.

  • MLA stands for Micro Lens Array. It's a new technology designed to enhance the performance of OLED TVs. MLA involves adding a layer of microscopic lenses on top of the existing OLED pixels. These lenses are incredibly small – thousands can fit over a single pixel.

Turntable Components

  • Phono (more specifically, Phono Preamplifier): An essential component for turntables. The signal from a turntable cartridge is very weak, and a phono preamplifier boosts this signal to a level that can be properly handled by an amplifier or receiver.

  • Cartridge: The part of a turntable that houses the needle (stylus). The cartridge converts the vibrations from the record grooves into an electrical signal that's sent to the phono preamp.

  • Tonearm: The arm that holds the cartridge and guides it across the record. The tonearm has crucial adjustments for proper tracking force and alignment.

  • Platter: The heavy rotating disc where you place the vinyl record.

  • Headshell: The detachable part at the end of the tonearm where the cartridge is mounted.

  • Counterweight: A weight on the tonearm that helps adjust the tracking force (how much downward force the stylus applies to the record).

  • Plinth: The main base of the turntable that houses the motor, platter, tonearm, and other components.

  • Belt: In belt-drive turntables, an elastic belt connects the motor to the platter, transferring the rotational power.

  • Motor: The component that drives the platter at a consistent speed.

  • Stylus: The tiny needle-like part of a cartridge that makes direct contact with the grooves in your vinyl records. The vibrating movement of the stylus is translated into electrical signals that become the sound you hear.

  • Belt: A rubber belt found in belt-drive turntables. The belt connects the motor to the platter, transferring the rotational power that spins your record.

  • Feet: The small supports on the bottom of a turntable. Their primary function is to isolate your turntable from vibrations, ensuring a smoother playback experience.

  • Direct-drive Motor: The platter is directly attached to the motor shaft.

  • Belt-drive Motor:The motor is connected to the platter via a belt (see above).

  • Dust Cover: A hinged plastic cover that protects your turntable from dust and debris when not in use.

  • Needle: Another term for the stylus.

  • Switch: Controls the power to the turntable (on/off), and oftentimes controls playback functions like start and stop.

  • RPM: Stands for "Revolutions Per Minute". It indicates how many times a record spins in one minute.

  • 33 1/3 speed: The standard speed for playing long-playing records (LPs). Most full-size albums are designed to be played at this speed.

  • 45 speed: The standard speed for 7-inch singles

  • 78 speed: This speed was for older records, primarily produced before the 1950s. You'll need a specialized turntable or cartridge to play these.

Amplifier Classes

  • Class A Amps: These amplifiers keep their output transistors constantly conducting current. This leads to very low distortion but also lower efficiency (generating more heat).

  • Class B Amps: Use two sets of transistors, with one set handling the positive half of the audio signal and the other the negative half. This is more efficient than Class A, but can introduce crossover distortion.

  • Class A/B Amps: A very common design that combines aspects of Class A and B. It offers a good balance between sound quality and efficiency.

  • Class D Amps: These amplifiers use a switching design, resulting in very high efficiency. They are common in compact and portable audio devices because of their power efficiency.

Core Components

  • Receiver: A central hub for your audio system. It usually includes the following:
    • Amplifier to power speakers
    • Radio tuner (AM/FM and possibly digital radio)
    • Inputs for various audio sources (CD player, turntable, streaming devices)
    • Surround sound processing in home theater receivers.
  • Amplifier: A device that takes a weak audio signal and boosts it enough to drive speakers. Amplifiers can be standalone or integrated into receivers.
  • Processor: Primarily found in home theater setups, a processor decodes surround sound formats (Dolby Atmos, DTS:X) and manages audio signals before they reach the amplifier.
  • Integrated Amplifier: Combines a pre-amplifier and power amplifier into a single unit, offering streamlined control over your audio sources and speaker output.
  • Pre-Amp: Handles input switching, volume control, and (sometimes) tone adjustments. It prepares the signal before it's sent to the power amplifier.
  • Phono Stage: A specific type of pre-amplifier designed to boost and equalize the very weak signal from a turntable's cartridge.

Input Types

  • Unbalanced Inputs: Mostly use RCA connectors. These are standard for most consumer audio equipment.
  • Balanced Inputs: Mainly use XLR connectors. They're often found in professional audio gear for their superior noise rejection abilities.
  • Optical Inputs: Use fiber-optic cables to transmit digital audio signals. Common for connecting TVs, CD players, and other digital sources.