Audio Terminology And Definitions Dictionary

 

Harmonics  Multiples of the fundamental sine wave frequency. A 50 Hz sine wave has a second harmonic at 100Hz, a third harmonic at 150 Hz, a fourth harmonic at 200 Hz, a fifth harmonic at 250 Hz and so on. The timbre of a musical instrument is defined by the complex mix of harmonics overlain on each note. In amplifiers, harmonic distortion is the addition of unwanted harmonics to the signal. Total Harmonic Distortion is the summation of all harmonic distortions.

 

Harmonic Distortion     Harmonic distortion is always related in some way to the frequency of the original signal. For instance, an input signal consisting of a 440 Hz tone (middle "A" to musicians) might result in an output signal with a large 440 Hz component and a much smaller 880 Hz component (a multiple of the original). Small amounts of frequencies that are harmonically related to the original are rarely audible. Larger amounts generally are audible, but this depends on how complex the original signal was in the first place. Humans hear harmonic distortion more readily when the original signal is composed of pure tones than they do when listening to complex musical passages. (Also known as Total Harmonic Distortion, or THD.)

 

HD-DVD   A high-resolution video disc format originally backed by Toshiba. It lost the most recent "format war" to Blu-ray. 

 

HDCD (High-Definition Compatible Digital)    HDCD is a codec (encode/decode) process that places additional information on a Red Book–standard CD without affecting playback compatibility on conventional CD players. 

 

HDCP (High-Bandwidth Digital Copy Protection) HDCP is a flexible copy-protection process for high-definition video content implemented through a software/hardware combination. It allows for specific use restrictions to prevent unauthorized copying of protected material. 

 

HDMI (High-Definition Multimedia Interface)  HDMI is an evolving standard that allows component-to-component video and audio signal transfer through a single multi-conductor cable. Be aware that there are multiple HDMI versions, each with its own list of potential capabilities. Also note that this list is not mandatory and that not all HDMI Version 1.4 implementations, for example, have the same features. HDCP is incorporated in HDMI. 

 

HDTV (High-Definition Television)     HDTV refers to a series of FCC-approved broadcast standards for consumer use as well as guidelines for the hardware used to display HDTV images.

The two main HDTV broadcast standards are:

·   720p (720 lines of resolution scanned progressively): provides a film-like image and takes up less bandwidth than 1080i. ABC and FOX are early adaptors of 720p. 

·   1080i (1,080 lines of resolution scanned in interlaced format, with alternate fields consisting of 540 lines each): the most common HDTV format. Used by PBS, NBC, CBS, and others. 

In addition, 1080p (1,080 lines scanned progressively) is a popular non-broadcast standard, but this standard requires on-board processing in the display device. Many Blu-ray discs provide 1080p signals. 

 

Hertz (Hz)   The frequency of an audio signal, or the number of times per second an object vibrates. This was originally stated as "cycles per second." The term "hertz" is named after Heinrich Hertz (1857–1984), a German physicist who did important work on electromagnetism. One hertz is defined as one cycle per second, so an object vibrating sixty times per minute (60 RPM) has a frequency of one hertz.  As stated elsewhere, audible frequencies (those we can hear) range from 20 Hz (low bass) to 20,000 Hz, often stated as 20 kHz (high treble).

 

Hi-Fi   Abbreviation of High Fidelity. Literally means honesty or truthfulness. In audio terms the context is accuracy to the original recorded signal, or more  broadly authenticity to the composed music.

 

High-Pass Filter  A circuit (e.g., a speaker crossover) that progressively attenuates signals below a pre-determined frequency but allows higher frequencies to "pass" through. (See also: low-pass filter.)

 

Home Theater Receiver   Also called an A/V (audio/video) receiver, this component is the functional equivalent of a conventional stereo receiver but includes many more inputs and outputs specific to the needs of a home theater user.

 

Home Theater System  A collection of audio and video equipment designed to closely replicate the commercial theater experience in a home setting. A typical home theater system will include a large-screen television, a high-quality program delivery system (such as a DVD player, HD satellite TV, or HD cable TV), and a multi-channel surround sound audio system.

 

Home Theater in a Box (HTiB)  An all-in-one home theater audio system often marketed, packaged, and sold in a single box. This "all-in-one" packaging supposedly makes a consumer's buying decision simpler, but frequently it offers substantially less performance than systems composed of separate, individually chosen components.

 

Horn   A flared structure often used to assist a 
loudspeaker. Horn-loaded loudspeakers are 
considerably more efficient than ordinary moving coil 
loudspeakers in turning electrical into acoustic energy.

 

Hz   Shortened form of Hertz (cycles per second).