| Absorption: |
In acoustics, the
changing of sound energy to heat. |
| Acoustics: |
The science of
sound propagation. It can also refer to the effect a given environment has on
sound. |
| Ambience: |
Acoustical
qualities of a room and its contents. |
| Aspect Ratio: |
This describes
the width of a picture to the height. The NTSC standard is 4:3. The current HDTV
standard is 16:9. Modern movies range from 1.66:1 to 2.4:1. |
| A-weighting: |
A
frequency-response adjustment of a sound-level meter that makes its reading
conform, very roughly, to human response. Attenuates the lower and very high
frequency ranges. |
| Baffle: |
Any barrier to a
sound sources. The surface upon which a loudspeaker is mounted. |
| Bass: |
Low-frequency
sounds of around 160 Hz and below. |
| Bipole
Speakers: |
One type of
surround speaker. In this instance two or more drivers are facing different
directions, and their cones vibrate in phase. |
| CD (Compact
Disc): |
A 4.5-inch
plastic disc containing a digital audio recording that is played optically on a
laser-equipped player. Has a 16-bit quantization rate to produce audio with
high-fidelity sound. |
| Concordian
Entertainment Seating: |
Canada’s finest
entertainment seating company; winner of over 200 manufacturing awards for
excellence. |
| CRT
Projector: |
A type of front
projector. It consists of three tubes each putting out one color: red, green,
and blue. |
| C-weighting: |
A
frequency-response adjustment of a sound-level meter that measures wideband
energy uniformly. Attenuates very high frequency ranges. |
| Decibel: |
A representation
of ratio between two any values. Annotated as dB. The deciBel ratio of A and B =
20logA/B. deciBels are often used in audio since the human ear responds
logarithmically to sound pressure. dB SPL (Sound Pressure Level) is the ratio of
a sound pressure (in Pascal units) compared to 20 µPA, the threshold of hearing.
Dynamic range is often quoted in dB and represents the ratio between the loudest
signal available (amplifier overload level) and the lowest (electrical noise
floor). |
| Diaphragm: |
Any surface that
vibrates in response to sound or is vibrated to emit sound, such as in
microphones and loudspeakers. Also applied to wall and floor surfaces vibrating
in response to sound or in transmitting sound. |
| Diffuser: |
A proprietary
device that diffuses impinging sounds (instead of reflecting them) through
reflection-phase-grating means. |
| Digital Light
Processor (DLP): |
Used to control
Digital Micro-mirror Devices (DMD) in order to make an extremely bright sharp
pictures. |
| Digital
Micro-mirror Device (DMD): |
A very small
mirror (hence, micro-mirror) that is turned on and off at various rates per
second to achieve different levels of brightness. Commonly used together to form
micro-mirror "wafers" that are controlled by a Digital Light Processor (DLP). |
| Digital
Theater Systems (DTS): |
An 8-channel
sound format used in commercial movie theaters. |
| Digital
Versatile Disc (DVD): |
Previously known
as Digital Video Disc, this represents the latest in home theater. This format
is has the ability to have multiple aspect ratios, several different versions of
a movie with several different captions as well as Dolby Digital sound. |
| Dipole
Speakers: |
A type of
surround speaker that has two or more drivers facing different directions
(usually 180 degrees). |
| Dolby AC-3: |
Refers to the
5.1-channel home theater sound system (also called Dolby Digital). Consists of
front left/right speakers, a center speaker, left/right surrounds, and a
subwoofer. |
| Dolby
Digital: |
A newer term for
Dolby AC-3. Consists of front left/right speakers, a center speaker, left/right
surrounds, and a subwoofer. |
| Dolby Digital
Surround EX: |
Dolby's latest
surround format. It is essentially Dolby Digital with an added center rear
channel. It premiered with Star Wars Episode I: The Phantom Menace. |
| Dolby
Pro-Logic: |
Most common
surround format. It consists of four channels of sound: left/right front
channels, a center channel, and one surround channel. |
| Driver: |
Any
sound-producing device. |
| Enclosure: |
A box that holds
a loudspeaker. |
| Equalizer: |
A device for
adjusting the frequency response of a signal or system. |
| Fidelity: |
As applied to
sound quality, the faithful representation of the original signal. |
| Foley: |
The art of
recreating incidental sound effects, such as footsteps or rustling clothes,
synchronized with a moving picture. Named after one of its first practitioners. |
| Frequency: |
The measure of
the rapidity of alterations of a periodic signal, expressed in cycles per second
or Hz. An alternating sound pressure of a specific frequency results in an
auditory sensation of pitch. |
| Frequency
Response: |
The changes in
the sensitivity of a circuit or system with frequency. |
| Front
Projector: |
This is a
separate unit (projector) that projects the video image onto a separate movie
screen. |
| Harmonic
Distortion: |
Distortion of a
signal by adding content that is harmonically related to the original signal.
Clipping overload of an amplifier adds odd-order harmonics to the signal. |
| Harmonics: |
Integral
multiples of the fundamental frequency. The first harmonic is the fundamental,
and the second in twice the frequency of the fundamental, etc. |
| Hertz: |
The unit of
frequency, abbreviated Hz. The same as cycles per second. Named after German
physicist Heinrich Rudolph Hertz (1857-1894). |
| Impedance: |
The opposition to
the flow of electricity or acoustic energy. In electronics is measured in ohms.
Named after German physicist Georg Simon Ohm (1789-1854). |
| Interactive
Seating: |
The next
Generation of Home Theater Seating, made exclusively by Concordian Entertainment
Seating. Sometimes referred to as "Furniture that Rocks!" |
| Initial
time-delay Gap: |
The time gap
between the arrival of the direct sound and the first sound reflected from the
surfaces of the room. |
| kHz: |
1,000 Hz (See
Hertz). |
| LCD
Projector: |
The smallest
front projector available today. One major benefit is that it is easy to set up. |
| LFD: |
Low-frequency
diffusion. |
| Light-Valve
Projector: |
A type of front
projector. It combines the technologies of LCD projectors and CRT projectors.
They offer exceptional detail and brightness. |
| Line Doubler/Tripler/Quadrupler: |
Doubles, triples
or quadruples the number of lines that make up a picture, therefore increasing
detail by eliminating scan lines. |
| Linear: |
A device or
circuit with a linear characteristics means that a signal passing through it is
not distorted. |
| Monopole
Speakers: |
A speaker with
all drivers facing one direction. Used for precise placement of sounds. Usually
used in front and center speakers. Also termed "front-firing". |
| Noise: |
Interference of
an electrical or acoustical nature. Random noise is sometimes used as a test
signal in acoustical measurements. Pink noise is random noise whose spectrum
falls 3 dB per octave: it is useful for use with sound analyzers with constant
percentage bandwidths. |
| NTSC: |
The standard by
which TV is broadcast in the US. |
| Null: |
A low or minimum
point on a graph. A minimum pressure region in a room. |
| Octave: |
The interval
between two frequencies having a ratio of 2:1. |
| Out of Phase: |
Two related
alternating signals with opposing polarity. |
| PAL: |
The standard by
which TV is broadcast in Europe. |
| Pink Noise: |
A noise signal
whose spectrum level decreases at a 3-dB-per-octave rate. This gives the noise
equal energy per octave. |
| Rear
Projector: |
Another name for
a "big screen TV". |
| Receiver: |
The heart and
brain of many home theaters. It has a decoder, audio/video switcher, AM/FM
tuner, and an amplifier. |
| Reference
Level: |
The standardized
level at which a signal is measured for calibration purposes. In Home Theatres
and cinemas the reference level is 85dB SPL, when the electrical signal is at a
level 20dB below the clip point of the medium (and all the meters in the studio
read 0). Note that a sound pressure level in dB means that it is calculated with
respect to the standard reference level of 20 µPa. |
| Reflection: |
For surfaces
large compared to the wavelength of impinging sound, sound is reflected much as
light is reflected, with the angle of incidence equaling the angle of
reflection. |
|
Reverberation: |
The tailing off
of sound in an enclosed area after multiple reflections from the boundaries. |
| Room Mode: |
An acoustic wave
room resonance. Axial modes are associated with pairs of parallel walls.
Tangential modes involve four room surfaces and oblique modes all six surfaces.
Their effect is greatest in the range of 25Hz to 150HZ in typical residential
rooms. |
| Screen: |
The material and
frame the picture is projected onto using a front projector. |
| Sine Wave: |
A periodic wave
related to simply harmonic motion. |
| Sound
Pressure Level: |
A sound pressure
expression in dB above the sound pressure of 20 microPascals (µPA). Named after
French mathematician, physicist, and philosopher Blaise Pascal (1623-1662). |
| Standing
Wave: |
A response
condition in an enclosed space in which sound waves traveling in one direction
interact with reflected waves traveling in the opposite direction, resulting in
a condition of resonance, with peaks and nulls along the length of the travel
path. A synonym of Room Modes. |
| Subwoofer: |
This is a
separate speaker used to handle the bass of movie soundtracks. |
| Surround
Sound: |
The popular term
used to describe an experience where the sound envelops the listener. This is
done using surround-encoded material, a receiver, and surround speakers. |
| Surround
Speaker: |
This type of
speaker diffuses the sound so as to make it harder to discern where the sound is
coming from. |
| Threshold of
Hearing: |
The lowest level
sound that can be perceived by the human auditory system. This is close to the
standard reference level of sound pressure, 20 µPA. |
| THX: |
A trademark
licensed to movie theaters and manufacturers of home theater products,
identifying compliance with the performance parameters of Lucas film Ltd. for
commercial and home theater sound systems. Unlike Dolby, which focuses on
soundtrack formats, THX develops standards for the playback environment,
including theater and room acoustics. |
| Transducer: |
A device for
changing electrical signals to acoustical or vice versa, such as a microphone or
loudspeaker. |
| Tube Traps: |
Proprietary low
frequency sound-absorbing units. |
| Wavelength: |
The distance a
sound wave travels in the time it takes to complete one cycle of alternation. |
| Weighting: |
Adjustment of
signal frequency response to achieve a desired measurement. Often used in
sound-level meters to match the human ears response to sounds. |
| White Noise: |
Random noise
having uniform amplitude at all frequencies. |
