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multimedia files quickly, so the client browser
or plug-in can start displaying the data before
the entire file has been transmitted.
Subwoofer
The extra-low frequency drive-unit
(loudspeaker) that can be used to augment
both stereo and surround system.
T
Treble
High frequencies at the top end of the audio
band i.e. above 3kHz.
Tweeter
The drive unit (loudspeaker) that reproduces
high frequency sounds.
U
UPnP (Universal Plug and Play)
Universal Plug and Play is a networking
architecture developed by a consortium
of companies to ensure easy connectivity
between products from different vendors.
UPnP devices should be able to connect to a
network automatically, handling identification
and other processes on the fly. The standards
developed by the UPnP Forum are media-,
platform-, and device-independent.
USB (universal serial bus)
A hardware interface used to connect devices
such as computer audio players, digital
cameras, and more. USB is UPnP enabled
(also called hot-swappable), meaning that a
computer does not need to be turned off
when new devices are plugged in and the
devices do not need to be configured. USB
supports data transfer rates of up to 60MB
per second (in USB 2.0).
V
VBR (variable bit rate)
With VBR, the encoder takes as much bits
as it needs. So black pictures get few bits and
PDIF allows the transfer of digital audio signals
from one device to another, without the need
to convert first to analog. This prevents the
quality of the digital signal degrading during
transfer to analog.
Sampling rate
The precision with which a digital file
describes the analog sound it represents.
Basically, a lower rate produces files that
sound worse and take up less drive space
than those with a higher rate. CDs have a
sampling rate of 44.1kHz, and DAT machines
have a sampling rate of 48kHz. MiniDisc
player/recorders with a built-in sampling rate
converter can handle both rates.
Sensitivity
Volume that a speaker offers for a specific
voltage input, expressed in decibels per watt
(dB/W).
Shuffle
A feature that plays audio files (tracks) in
random order.
Signal to noise ratio
Represents the difference between the level
of the audio signal, and any interference. The
larger the figure, the purer the sound.
SPL (sound pressure level)
An acoustic measurement of sound energy.
1 dB SPL is the smallest increment in sound
level to which the average human is sensitive.
Theoretically, 0 dB SPL is the threshold of
human hearing while approximately 120 dB is
the threshold of pain.
Stereo
Literally means solid. Usually taken to refer to
two channel stereo, though developments in
digital audio facilitate multichannel stereo.
Streaming
A technique for transferring data such that it
can be processed as a steady and continuous
stream. Streaming technologies are often used
on the Internet because many users do not
have fast enough access to download large
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