Apple Logic Express 7 - Manual (Page 295)

Chapter 11 Sample Editor 295
Audio Energizer
The purpose of the Audio Energizer is to increase the perceived volume of audio
material, while altering the sound as little as possible, and without causing clipping.
Digital distortion (which would be the inevitable result of simply increasing the level,
and which sounds very unpleasant) is avoided by using this algorithm.
You could compare the effect to that of an analog tape which is saturated by a high
recording level. The distortion factor and effect on the audio material is much lower,
however.
Here’s an example of the effect. If a normalized audio file (audio data which is already
at the maximum dynamic range) is edited, the effect is as follows: a VU meter will
show a higher level, indicating increased average energy in the signal. A peak display
will show the same level as before, as the maximum signal level has not been
exceeded.
Opening the Audio Energizer
Select Factory > Audio Energizer in the Sample Editor. The function is executed by
clicking the Energize button.
Parameters
The main parameter is Factor. This is where you select the amount of average level
boost. 0% means no alteration, while higher values produce an increase in energy. The
setting you make here will depend on the audio material, situation, and personal taste.
Begin by trying values in the 40 to 100% range. Values below 10% will have little effect,
values over 100% can lead to undesirable alterations in the sound, depending on the
material. Values over 200% are not recommended with normalized files, because they
will have detrimental effects on the sound and it’s dynamics. They can also greatly
increase the required computation time. On non-normalized audio data, even high
values can be effective because the overall level is initially increased to it’s maximum,
without affecting the dynamic range.