Adobe AUDITION 1.5 - Manual (Page 292)

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Glossary
Normalize To adjust the highest peak of a waveform to a certain percentage relative to the
digital maximum, 0 dBFS, thereby raising or lowering all other peaks accordingly.
Typically, audio is normalized to 100% to achieve maximum volume, but Adobe Audition
lets you normalize to any percentage.
Nyquist Frequency Also called Nyquist Rate, this frequency equals half the current sample
rate and determines the highest reproducible audio frequency for that sample rate. For
example, audio CDs use a sampling rate of 44,100 Hz because the resulting Nyquist
Frequency is 22,050 Hz— just above the limit of human hearing, 20,000 Hz. Likewise, to
reproduce a signal with an 11,000 Hz frequency range, you must use a sample rate of at
least 22,000 Hz. To avoid aliasing distortion, nearly all analog-to-digital converters filter
out frequencies that exceed the Nyquist Frequency before the analog-to-digital conversion
process. For the best audio quality, record and edit at higher sample rates and then convert
down if needed.
O
Offline editing See “Destructive editing” on page 279.
Order A value that determines the slope of an audio filter. First-order filters attenuate an
additional 6 dB per octave, second-order filters attenuate 12 dB, third-order filters 18 dB,
and so on.
P
PCM (Pulse Code Modulation) PCM is the standard method used to digitally encode audio
and is the basic, uncompressed data format used in file formats such as WAV and AIFF.
Peak files Cache files with the extension .pk that enable Adobe Audition to open, save, and
redraw audio files more quickly. You can safely delete peak files or deselect the Save Peak
Cache Files option in the Settings dialog box. However, keep in mind that without peak
files, larger audio files will reopen more slowly.
Phase The position of a sound wave relative to other sound waves. As a sound wave travels
through the air, it compresses and expands air molecules in peaks and troughs, much like
an ocean wave. In the waveform display, peaks appear above the center line, troughs
appear below. If two channels of a stereo waveform are exactly opposite in phase, they will
cancel each other out. More common, however, are slightly out-of-phase waves, which
have misaligned peaks and troughs, resulting in duller sound.
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