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SR
An acronym for Sound Reinforcement, which
refers to the process (or a system for) amplify-
ing acoustic and electronic sounds from a per-
formance or speech so that a large audience can
hear clearly. Or, in popular music, so that a
large audience can be excited, stunned or even
partially deafened by the tremendous amplifica-
tion. The term “SR” is to “PA” (Public Address)
as the term “environmental cleanup technolo-
gist” is to “garbage collector”.
steradians
Just as a radian is an angular unit of measure in
2-dimensional space, so a steradian is an angu-
lar unit of measure in 3-dimensional space
(solid angle).
stereo
Believe it or not, stereo comes from a Greek
word that means solid. We use stereo or ste-
reophony to describe the illusion of a continu-
ous, spacious sound field that is seemingly
spread around the listener by two or more
related audio signals. In practice, stereo often is
taken to simply mean two channels.
surround sound
Multi-channel audio playback systems in four,
five, or six channel formats. Surround sound is
typically found in movie theaters and home
theater systems.
sweep EQ
An equalizer that allows you to “sweep” or con-
tinuously vary the frequency of one or more
sections.
symmetrically balanced
See
balanced
.
T
tinnitus
The ringing in the ears that often results from
prolonged exposure to very loud sound levels.
A sound in the ears, such as buzzing, ringing, or
whistling, caused by volume knob abuse!
trim
In audio mixers, the gain adjustment for the
first amplification stage of the mixer. The trim
control allows the mixer to accommodate the
wide range of input signal levels that come
from real-world sources. It is important to set
the trim control correctly; its setting determines
the overall noise performance in that channel
of the mixer. See
mic preamp
.
TRS
Acronym for Tip-Ring-Sleeve, the three parts of
a two-conductor (plus shield) phone plug. Since
the plug or jack can carry two signals and a
common ground, TRS connectors are often
referred to as stereo or balanced plugs or jacks.
Another common TRS application is for
insert
jacks, used for inserting an external processor
into the signal path.
TS
Acronym for Tip-Sleeve, the two parts of a sin-
gle conductor (plus shield) phone plug. TS con-
nectors are sometimes called mono or
unbalanced plugs or jacks. A 1/4” TS phone
plug or jack is also called a standard phone plug
or jack.
U
unbalanced
An electrical circuit in which the two legs of the
circuit do not have the identical impedance to
ground. Often one leg is also at ground poten-
