User Guide

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ADOBE AUDITION
User Guide
If Dither isn’t checked, quiet audio passages will just fade in and out of a disruptive, “choppy” sound that resembles
falling rain or static. Whether or not dithering is used depends on the audio that’s being converted and, of course, your
preferences.
Enable Dithering Check this box to activate Dithering; uncheck the box to turn Dithering off.
Note: If Dithering isn’t enabled, Adobe Audition truncates instead. This means that bits that aren’t used are simply chopped
off and discarded. This gives a “crackly” effect that fades in and out on very quiet audio passages.
Dither Depth (bits) This sets the bit amount of Dither to be applied. Generally, values of 0.2 to 0.7 give the best results
without adding too much noise. Note, however, that as this value is lowered, other unwanted harmonic distortion noise
will appear. (You can usually get away with lower values for the Dither Depth when you use Noise Shaping.)
p.d.f.: The “probability distribution function” controls how the dithered noise is distributed away from the original
audio sample value. Five p.d.f. types are available from the drop-down list: Rectangular, Triangular, Gaussian, Shaped
Triangular, and Shaped Gaussian.
The Rectangular function means there’s an equal chance that the noise value added will lie anywhere between +1 and -
1 (i.e., the likelihood of a value of -0.8 being chosen is the same as that of 0.2, or 0.3, or any value between -1 and +1).
The Triangular function chooses random numbers that are generally closer to 0 than to the edges -1 or +1 (i.e., the
chance of 0 being chosen is twice as great as the chance of choosing 0.5 or -0.5). All dithering distribution functions can
linearize the quantization noise, meaning that the noise that’s heard doesn’t depend on the frequency of the dithered
audio, thus no harmonic distortion appears. The SNR Loss is measured against the undithered case. If modulation is
present, the audible noise floor rises and falls depending on the amplitude of the signal, so generally one doesn’t want
this either.
Usually a Triangular p.d.f. function is a wise choice, because it gives the best tradeoff between SNR, distortion, and noise
modulation.
Noise Shaping Select one of the several noise shaping presets (known as “noise shaping curves”) to have Adobe Audition
determine the placement when moving noise to different frequencies. The same amount of noise overall is present, but
you can choose less noise to be placed at one frequency at the expense of placing more noise at another. You may also
specify that no noise shaping is used.
p.d.f. SNR Loss Modulation
Rectangular 3dB Yes
Triangular 4.8dB No
Gaussian 6dB Negligible
Shaped Triangular 4.8dB No
Shaped Gaussian 6dB Negligible