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