Apple Logic Pro 8 User Manual
Page 513
Chapter 21
Editing Audio in the Sample Editor
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The process is single ended, meaning it affects material which is already recorded, and
there is no need to decode the signal during playback. This means that even noise
present in the original signal can be processed.
To use noise reduction:
1
Turn the Spike Reduction function off, by moving the Sensitivity slider to the extreme
right.
This ensures that only the Noise Reduction function is used.
2
Drag the Strength slider to the desired position.
 Off means no edit.
 Min is the smallest possible edit. Values closer to Min have a small effect.
 Max results in the maximum possible reduction of the noise component.
The “correct” value depends on the quality of the material, and your own personal
taste. Good quality material should be edited using Min or values close to it. You will
probably only notice minor changes in the sound. Bad (noisy) quality material should
be processed at higher values, or even Max. If the setting is too high, the treble
component of the signal will be reduced.
3
Click the Process button to execute the function.
Note: The Silencer function is optimized for normalized data. Low level material should
be normalized before processing.
Spike Reduction
The aim of Spike Reduction is to identify and reduce signals such as pops, clicks, or
digital spikes, in order to reconstruct a hypothetical original signal.
To use spike reduction:
1
Turn the Noise Reduction function off, by moving the Strength slider to the extreme
right.
This ensures that only the Spike Reduction function is active.
2
Drag the Sensitivity slider to the desired position. This parameter determines the
threshold level used for the recognition of spikes (loud bits) in the audio file.
 When set to High (sensitivity), relatively small signal spikes are identified.
 When set to Auto, the threshold is controlled automatically. Useful on most
material.
 Use Low to identify most signal peaks as spikes.
3
Drag the Method slider to determine how spikes are processed.
 Gentle is the weakest algorithm, and only slightly smooths the original signal.
 Aggressive is the strongest, and has a very noticeable impact on the audio.