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PROCESSING AUDIO CHP. 10
Normalize to
This fader specifies the level to which the highest peak should be set.
• With
Peak level, if the peak level is -10 dB and the Normalize to value is -3 dB, a constant boost of 7 dB is
applied to the entire file.
• With
Average RMS power, normalizing to 0 dB means boosting the signal until it has the same apparent
loudness as a 0 dB square wave. This results in all the dynamic range of the signal being flattened and all
peaks being either clipped or seriously compressed. For more information, see If clipping occurs on page 161.
Note:
As a rule, normalizing using Peak levels to 0 dB is
acceptable, but normalizing using
Average RMS power to
anything above -6 dB is not recommended.
Scan settings area
The controls in this area allow you to determine the response of the RMS power scan to the dynamics in the
file.
• The
Ignore below fader determines the level of audio data included in the RMS calculation. Data below
the threshold is ignored, effectively eliminating silent sections from RMS calculation. The
Ignore below
fader should be set a few dB above perceived silence. If
Ignore below is set to -Inf., all audio data is used.
However, if the value is set too high (above -10 dB) the RMS value may never rise above the threshold.
In this case, normalization cannot occur. For this reason, you should evaluate the threshold by clicking
the
Scan Levels button. For more information, see Scan Levels on page 160.
• The
Attack time value determines how quickly the scan responds to transient peaks.
• The
Release time value determines how quickly the scan should stop using transient peak material after it
begins to drop in level. Slower release times result in more data being included in RMS calculation.
• Selecting the
Use equal loudness contour check box allows the scan to compensate for the Fletcher-Munson
Equal Loudness Contours. The Fletcher-Munson Equal Loudness Contours illustrate that very low- and
high-frequency audio is less perceptible to the human ear than mid-range audio. Therefore, selecting this
option forces the scan to factor this into RMS calculation.
Scan Levels
Clicking Scan Levels initiates Peak and RMS scans on the audio and displays the RMS level and the highest
peak level detected. When previewing a normalize effect, the entire file must be scanned to preview a even
small selection. Clicking
Scan Levels saves the current Peak and RMS values and allows you to preview
different
Normalize to settings without re-scanning the entire file.
An asterisk adjacent to a level value indicates that the value is not current. This occurs when the selection is
updated or the dialog is initially opened. To update values, click
Scan Levels.
Current Peak and RMS levels
Noncurrent Peak and RMS levels