AIFF--Audio
Interchange File Format developed by Apple for the Macintosh
OS. Compare to the Windows .wav format, but these files
contain more information in a header section which allows the
possibility of more advanced audio processing.
ALIASING--Unwanted
noise
that occurs from sampling a frequency at a sample rate that is less
than what is required to accurately represent that frequency. (See
Nyquist Theorem.)
AMPLITUDE--Amplitude
represents the loudness of a signal, measured by its distance from
the center-line (= 0 amplitude value). Amplitude is most often
measured in decibels (dB).
ANALOG--Represents
events that are recorded as continuous, as opposed to digital,
where events are recorded as discrete steps or numbers.
Example: a wristwatch with hands would be analog, whereas an
LED/LCD watch with only number readings would be digital. In
terms of recording, an analog recording uses voltages to represent
acoustical vibrations that are normally recorded as a corresponding
series of magnetic fluctuations on tape.
AU--A
file format native to Sun workstations. It remains in use due
in part to the fact that most Internet servers are running
Unix.
AUDIO FILE FORMAT--The
method used for writing audio data to disk for storage is known as
File Format. Not all file formats are compatible. Windows PCM
(.wav) is found most often in the Windows environment. Typically, a
variety of file formats
can be chosen under the menu heading File when saving.
BAUD RATE--The number of bits per second being
transmitted.
BIOS--Basic Input Output
System that controls a computer and provides its low-level routines.
It is the BIOS which handles the instructions for starting a
computer, initializing the hardware, and launching the operating
system.
BIT--Part of the digital
numbering system used in electronic equipment. A bit makes up a
larger number, called a word, which is used to represent the voltage
level (amplitude) of an analog signal. The number of bits used to
make up a word determines the bit resolution, which in turn
determines the number of voltage levels possible in representing
amplitude. Therefore, greater bit resolutions make for higher
signal-to-noise ratios.
BIT RESOLUTION--The
number of bits used in measuring amplitude for a sample. Choosing
8-bit resolution will provide 256 possible unique
"volumes", while choosing a 16-bit resolution will provide
65,536 possible unique "volumes," which results in a 96 dB
signal-to-noise ratio. Obviously, a much greater dynamic range can
be reproduced at 16-bit resolution than at 8-bit resolution, which
only has a 48 dB signal-to-noise ratio. Compact disk players have a
16-bit resolution. Some sound cards support resolutions greater than
16-bit. Audition supports up to 32-bit sample
rates. It is best to remain at the 32-bit level while working in
Audition, and convert down for output, in order to best represent
the audio after transforms have been preformed. (The more bits are used to describe each sample, the more possible amplitudes it has. Eight-bit sound allows for each sample to have 256 possible amplitudes, 16-bit allows for
65,536, and 24-bit allows for almost 16.8 million amplitudes.)
BROWN NOISE--See Noise, Brown.
BURN--Writing
to a CD-R or CD-RW.
CD--Compact disc (audio only). A digital
storage medium that holds 700 MB of data, or 80 minutes of digital
audio; uses a 44.1kHz sample rate, Stereo, 16-bit
linear PCM.
.CDA--Compact Disc Audio (CD-DA, Compact
Disc-Digital Audio), a format which is the basis for most commercial
CDs.
.CEL--Cool Edit Loop file format, compressed
but does not extend file time lengths.
CD-R--A
CD that may be recorded one time--available in two capacities: 650 MB (74-minute) and 700 MB (80-minute).
Mini CD-R--available in a 180 MB (21-minute) capacity only.
CD-RW--A CD
that may be re-recorded--available in a 650 MB (74-minute) capacity only..
You cannot play a music CD made on a CD-RW disc in most home or car stereo CD players.
CHORUS
EFFECT--Combining the main signal with several delayed versions
of the signal. It replicates the effect of a chorus singing a single
note providing a fuller sound.
CLICK TRACK--An
audio track comprised of clicks that keep time, like a metronome.
They are silenced for the finished product.
CLIPPING--When
the amplitude of a signal exceeds the maximum level that is
available for current conditions (i.e. 256 in 8-bit audio), a
process known as clipping occurs. This causes the signal to distort,
and visually appears in the display as a "chopped-off"
waveform at the top. Lower recording, or source output, levels when
recording if you experience clipping.
CROSSFADE--To fade from one audio track to
another. One track fades as another increases in volume.
DAC--Digital-to-Analog Converter.
DAT--Digital Audio Tape. DAT
tapes are sampled at 16-bit and 32,000, 44,100, and 48,000 (which is
considered "DAT quality") samples per second.
DECIBEL (dB)--A
standard unit of loudness; 1/10th of a Bel (named after Alexander
Graham Bell). Example: threshold of hearing = 0 dB; normal
conversation = 60 dB; threshold of pain = 130 dB.
DIGITAL--Events
are recorded as discrete steps or numbers, as opposed to analog,
where events are recorded as continuous. Using numbers
(digital) to represent acoustical vibrations which are measured at
equal intervals of time.
DISC--Storage medium for music or video information.
DISK--Computer storage medium, usually 3.5".
DITHERING--Adding a low level of noise to an audio signal
so that fainter audio can be heard that otherwise would be cut off
when converting from a higher bit rate to a lower bit rate (e.g.,
converting 24-bit to 16-bit).
DVD--Digital Video (or
Versatile) Disc. A storage medium similar to Compact Disc (CD), but
with much higher bandwidth and storage capabilities. Audio stored on
DVD movies is generally 96 kHz/24-bit.
EFFECTS--Echo, Chorus, Digital Delay,
Reverb and other modifications produced by passing a sound or audio
signal through an effects processor.
EQUALIZATION--Changing the frequency balance of the
original waveform by boosting or eliminating particular frequency
bands. An equalizer has a series of sliders, each with a
particular frequency listed beneath. One may increase or
decrease the volume of particular frequency ranges by adjusting the
sliders. (See Equalizer graphic under SoundStream on Roxio
Easy CD Creator page.)
FILE SIZE: Remember
that changing any of the three sample categories (sampling rate,
mono/stereo, bit resolution) will significantly change the file
size, as the chart below illustrates. Simply experiment to see
what settings will best meet your needs. (Red cell represents
CD-quality rate ... 10.3MB per minute.)
Approximate
file size for ONE MINUTE of sound
(1 floppy = 1.44 MB)
(1 CD-R = 700 MB) |
| Channels |
MONO |
MONO |
STEREO |
STEREO |
| Resolution |
8-BIT |
16-BIT |
8-BIT |
16-BIT |
| Sampling Rate |
|
|
|
|
| 44,100 Hz |
2.5 MB |
5.1 MB |
5.1 MB |
10.3 MB |
| 22,050 Hz |
1.2 MB |
2.5 MB |
2.5 MB |
5.1 MB |
| 11,025 Hz |
646 kb |
1.2 MB |
1.2 MB |
2.5 MB |
| 8,000 Hz |
469 kb |
938 kb |
938 kb |
1.8 MB |
FREQUENCY--Measured in Hertz (Hz),
vibrations per second that determine pitch. For example, the
orchestral tuning note, A440 = 400 vibrations per second, sounding
the pitch of "A."
FREQUENCY
RANGE (of human hearing)--A sound must have a frequency of roughly 20 Hz or
more on the low end to be heard. On the high end, young ears
can hear frequencies of up to 17,000 Hz (17 kHz) or more.
Older folks are doing well to hear 12 kHz frequencies.
HERTZ
(Hz)--The unit of measurement of frequency
equal to one cycle of a periodic waveform per second (in English ...
vibrations per second ;-). (K = thousand. 3 kHz = 3,000 Hz)
IMA--Interactive
Multimedia Association file format which has a 4-to-1 compression
ratio.
LEVEL METERS / VU (Volume Unit) METERS--Visual
meters that indicate the volume levels of incoming and outgoing
audio signals.
LIMITER--Limiters
are compressors with a compression ratio of 10:1. They reduce or
"limit" input signals that exceed a specified threshold
level, so that the output does not increase in gain beyond the
specified point.
MIDI--Musical Instrument Digital Interface, a
standardized protocol for communication between electronic devices
and computers. File extension is .mid
MIDI TIME CODE (MTC)--A method
of sending timing information between
MIDI
devices. For instance, SMPTE, which is an audio signal, can be
converted to MTC to sync to and control Cool Edit Pro's transport
from a device such as a VCR or tape deck.
MINIJACK
PORT COLORS--The 1/8" phone plug ports are typically color
coded. Red = microphone.
Green = speakers. Blue =
Line In. Black = Line Out. Hot Pink = Man, where'd you
buy that computer??
MINIPLUG--A 1/8" phone plug (stereo or
mono).
MIXDOWN--The process
of combining the output of all enabled tracks (or selected tracks)
into a new, single stereo waveform. When doing a Mixdown, track properties
such as Volume and Pan are reflected in the resulting waveform.
Mixdown is generally the final operation, done when you are happy
with the way your session sounds, or can be used to create submixes,
or mixes of selected tracks (such as all of the drums) which is
useful for uncluttering your workspace, or for creating alternate
mixes.
MOV--Apple's QuickTime file format, a common
multimedia player.
.MP3--technically,
"MP3-1 Audio Layer 3," as so-dubbed by the Motion Picture
Experts Group (MPEG). The short answer is that MP3 is a file
compression technique that reduces sound files to about one-tenth of
their original size. All the sounds are stored as
numbers. MP3 removes any numbers representing sounds beyond
the range of human hearing. While MP3 files aren't
"exactly" the same quality as a CD audio file, they come
pretty close.
MPEG--Audio
compression schemes created by the Motion Picture Experts Group.
MULTITRACK RECORDING--Recording sounds
on individual tracks that all play back at the same time (unless
muted).
MUTE--A switch
or control that zeroes out or turns off the audio from a specified
track.
NOISE, BROWN--Brown
noise has a spectral frequency of 1/f^2. This means that there is
much more low-end, and there are many more low-frequency components
to the noise. This results in thunder- and waterfall-like sounds.
Brown noise is so called because, when viewed, the wave follows a
Brownian motion curve. That is, the next sample in the waveform is
equal to the previous sample, plus a small random amount. When
graphed, this waveform looks like a mountain range. The wave pattern
is very predictable.
NOISE, PINK--Pink
noise has a spectral frequency of 1/f and is found mostly in nature.
It is the most natural sounding of the noises. By equalizing the
sounds, you can generate rainfall, waterfalls, wind, rushing river,
and other natural sounds. Pink noise is exactly between brown and
white noise (which is why some people used to call it tan noise, but
pink was more appealing). It is neither random nor predictable. It
has a fractal-like nature when viewed. When zoomed in, the pattern
looks identical to when zoomed out, except at a lower amplitude.
NOISE, WHITE--White noise
has a spectral frequency of 1. In other words, equal proportions of
all frequencies are present. Because the human ear is more
susceptible to high frequencies, white noise sounds very "hissy."
Cool Edit generates white noise by choosing random values for each
sample.
NYQUIST THEOREM--Signals
with frequencies up to a little less than half the sample rate can
be sampled without distortion. That is, the sampling rate must be at
least twice the number of cycles of vibration per second of the
highest recorded frequency in order to accurately represent the
sound without distortion. The Nyquist Frequency is that
magic sampling frequency where one can sample without distortion.
PAN--The
placement of sound left-to-right in the stereo field.
PCM--Pulse
Code Modulation is the standard method of digitally encoding audio.
It is the basic uncompressed data format used in file types such as
Windows' .wav and Apple's AIFF.
PINK NOISE--See Noise, Pink.
PUNCH IN--Selecting a specified area in which
to record or re-record.
RAM--Random
Access Memory, the memory required to load and run programs. This is
what you refer to when you say that your computer has 64 megabytes
of memory.
REAL AUDIO
(*.ra)--Real Audio is a compressed format used
for streaming audio over the Internet in real-time. You can save to
this format from 8- or 16-bit, mono or stereo, with a number of
valid sampling rates.
REVERB--An audio effect that adds a
spacious, echo-like character to a sound.
RM
or RAM--Real Audio Media file format used by RealNetworks,
one of the most commonly found streaming technologies on the
web.
RMF--Rich Music Format
developed by Beatnik; similar to MIDI files.
ROM--Read
Only Memory Memory that cannot be written to after it is constructed.
SAMPLE--To
digitize a sound, a number of snapshots, or samples, are taken every
second (sample rate) and are changed into numeric representations. A
sample is a single "snapshot" of the sound. The term
sample can also refer to the digitally recorded sound itself, i.e.,
the word can be a verb or a noun.
SAMPLE RATE--The sample
rate determines the number of times per second the snapshot of the
audio is taken. Higher sample rates produce higher quality audio,
but at the expense of requiring more disk space. Frequencies of up
to 1/2 the sample rate can be produced effectively, so to reproduce
a frequency of 10Khz, a sample rate of at least 20Khz must be
chosen. (See Nyquist Theorem.)
8,000 Hz = telephone quality
11,025
Hz = poor AM radio quality
16,000 Hz = reasonable compromise
between 11 KHz and 22 KHz
22,050 Hz = near FM radio quality
32,075
Hz = better than FM radio quality (Some boards support 32,000
instead)
44,100 Hz = CD quality
48,000 Hz = DAT quality
96,000 Hz
= DVD quality. (Also, see File Size chart above.)
SPECTRAL VIEW--The alternate view of waveform
data, as compared to waveform view. This mode is helpful for
spotting prevalent frequencies via color. Brighter colors
represent greater amplitudes. Dark blue represents virtually
no amplitude components within a frequency range. Bright
yellow represents higher-amplitude frequencies. Lower
frequencies appear near the bottom of the window, and higher
frequencies are displayed from the middle-to-top part of the scale.
SMPTE TIME CODE--Developed
by the Society of Motion Picture & Television Engineers (SMPTE),
this is the standard digital code used to synchronize sight and
sound.
S/N RATIO--The
Signal-to-Noise Ratio is the ratio between the noise floor (present
noise) and signal. Higher ratios are more desirable, as they
mask more background noise.
STRIPE--To
copy SMPTE time code to a single track of a multitrack tape. The
SMPTE is then used to reference time on the other tracks for
purposes of syncing those tracks to other devices.
SURROUND
SOUND--A feature of Audition, although there are a few
requirements your computer will have to meet first. Audition offers
six-channel surround sound whereby six speakers are placed in a
quasi-circular pattern around a central point ... the
listener.
TIME CODE--An
audio or digital signal designed to synchronize time between
multiple devices, such as audio and video. The most common forms are SMPTE and
MIDI
time code (MTC).
TRACK--A channel
on a tape recorder, sequencer or other recording device; one of a
set of concentric circles on a floppy disk.
.WAV--The
audio format for the Windows operating system, which has become the
standard for sampled audio on the web. .WAV encodes sound
using Pulse Code Modulation (PCM), a process that digitizes the
analog sound wave by sampling it a certain number of times per
second and storing each sample as an 8-bit or 16-bit
"word" (bit depth). The higher the sample rate and
bit depth, the more accurate is the sound reproduction. On the
down side, .wav files tend to be large. Audio CD resolution is
16-bit, stereo, 44.1 kHz. Web audio can be as low as 8-bit, 8 kHz.
WHITE NOISE--See Noise, White.
.WMA--Windows Media
Audio file, developed by Microsoft. Like MP3 files, WMA files
compress information. WMA files also have the ability to
program the file so it cannot be copied. WMA file sizes can be
significantly smaller than even the compressed MP3 files.
