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NAB
- The National Association of Broadcasters.
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Nasal - Reproduced sound
having the quality of a person speaking with his/her
nose blocked. Like the vowel "eh" coloration. In a
loudspeaker, often due to a measured peak in the upper
midrange followed by a complementary dip.
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Native
- Not counting, or prior to applying, any of:
scaling, upconversion, downconversion, encoding,
decodiing, modulation, demodulation, etc. For example
the native resolution of "720p HDTV" is 720
pixels high by
1280
pixels wide
but a particular TV set with a native 4:3 aspect ratio
resolution of 640 by 480 on an LCD panel can convert a
720p 16:9 program to fit by displaying half the
program's resolution horizontally and vertically, 640 by
360.
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Native
Format - Most digital televisions will
convert the 18
ATSC formats
into 1 or 2 formats and will draw only those. For these
sets, the ‘native’ format is the format the set will
draw.
·
Naturalness - Realism.
·
Near Field - Technically,
the region where the particle velocity is mostly out of
phase with the sound pressure-meaning that it can be
very close to the listener at higher frequencies.
Popularly (and incorrectly), it is often considered to
be any point where the direct sound is significantly
louder than the reflected
sound.
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Negative
Feedback - In all amplifiers, a part of the
output signal that is fed back and added to the input
signal out of phase, somewhat reducing the gain,
limiting distortion, and imparting stability. Negative
feedback, when used properly, can also improve frequency
response. At higher frequencies, the feedback may not
be fast enough, and the result will be increased
transient intermodulation distortion. Under most
conditions, this will not be audible. Feedback may be
used "locally," in sections of an amplifier, or
"generally," to control the response of the whole unit.
·
Negative
Gain Screen - Material that reflects less
light than a reference material. Often used for DLP and
LCD projection systems.
·
Neutral - Free from
coloration.
·
Noise
- An unwanted signal such as hiss, hum, whine,
static, buzzing, etc. Any spurious background sounds,
usually of a random or indeterminate pitch: hiss,
crackles, ticks, pops, whooshes.
·
Noise
Floor - The noise generated by an audio
device in the absence of any input signal.
·
Noise
Reduction (Audio) - A blanket term to
describe a variety of background-noise-suppressing
systems (Dolby, dbx, CX, etc.), which are employed in
audio and video sound systems. Even hi-fi video
recorders have proprietary audio noise-reduction
circuitry. Most digital-audio systems do not require
it.
·
Noise
Reduction (Video) - On some VCRs and
laser-video players, digital noise reduction is used to
improve picture quality, especially as it relates to
video grain and snow in dark.
·
Noise
Shaping - Digital recording techniques that
take advantage of the ear's reduced sensitivity at high
frequencies.
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Nominal - In home audio
there are two main uses of this term: 1. nominal power
rating- minimum amount of power recommended for a
speaker. 2. nominal impedance- theoretically the minimum
impedance a speaker will present to the amplifier.
·
Nonresonant - Materials that
don't vibrate much or absorb vibrations, which can
affect sound reproduction; materials often included in
the construction of a loudspeaker.
·
Notch
Filter - In video systems, this removes a
small part of the TV signal where color information is
most concentrated, reducing unwanted artifacts from
less-than-perfect signals.
·
Noticeable
- In aural perception, any sonic quality which is
clearly audible to most people.
·
NR
- Noise Reduction.
·
NTSC
(National Television System Committee) - U.S.
government and industry committee which defined the
525-line 60 (59.94) interlaced fields per second analog
broadcast TV standard over 50 years ago. (This format
is referred to as NTSC.) Of the 525 scan lines, 480
(give or take a few) contain the picture and the rest
contain synchronizing information, hold the encoded
closed caption text, and provide a time delay to move
the electron beam back to the top of the screen. NTSC is
used mainly in North America and Japan. Originally 30
frames per second, the standard was changed slightly to
29.97 frames per second at the time color was introduced
since that change made it easier to incorporate the
color information into what is now a composite video
signal. The change was so small that practically all
older TV sets continued to receive the signal properly
without loss of vertical hold.
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Numbering Scheme
(and disclaimer) - There are several numbering schemes
for
NTSC scan
lines as seen in textbooks. A few are described: (a)
Odd numbers between 1 to 483 inclusive denote lines for
the first field, then odd numbers from 485 to 525 denote
a vertical retrace interval, then even numbers from 2 to
482 denote the second field, then even numbers from 484
to 524 inclusive make up a vertical retrace interval.
(b) A retrace interval comes first, using odd scan
lines from 1 to 41 inclusive, then odd lines 43 to 525
inclusive make up the first field, then even lines 2 to
42 make up a retrace interval, then even lines 44 to 524
make up the second field. (c) Scan lines numbered
consecutively 1 to 21 make up a retrace interval, lines
numbered 22 to 263 make up the odd field, the following
retrace interval consists of lines numbered 264 to 284,
the lines of the even field (even) are numbered 285 to
525. Disclaimer: In any case the picture is supposed to
occupy at least 480 but not more than 483 scan lines. If
it does not occupy all 483 allowed scan lines, which
extra lines are left black may vary depending on the
make and model of equipment.
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Numerical Aperture
- A
number that represents the lens aperture of a laser
pick-up device.
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NUON
Enhanced -
Refers to a DVD
player that is NUON capable. VM Labs, Inc.'s NUON
feature provides the DVD player additional interactive
capabilities, such as game playing, when used with
software with NUON content. |
