7-22
Increasing or Decreasing Volume
Pro Audio provides three commands to boost or cut the volume of audio
data. The 3dB Louder and 3dB Quieter commands are used to increase
or decrease the volume by three decibels, respectively. For more
information on the decibel scale, see ÒThe Decibel ScaleÓ on page 7-7. You
can apply these commands several times in succession to get a larger
boost or decrease. The Normalize command ÒnormalizesÓ the audio
data: it boosts the volume until the maximum amplitude is reached
somewhere in the data. By normalizing the data, you achieve the
maximum possible volume without distortion or clipping. In addition,
you can use the Draw tool to adjust the volume of all audio events on a
track in a single step.
Like all the audio processing commands, these commands work by
modifying the waveform data. You can achieve volume changes
nondestructively by changing the event velocity or the volume envelope.
When increasing or decreasing the volume of audio events, you should
consider the following points:
¥ Normalize and 3dB Louder raise the noise ßoor; that is, while
they increase the volume of the signal, they also amplify the noise it
contains. (This is true when you raise the volume by other means,
too.)
¥ 3dB Louder, if applied to a signal that is already fairly loud, may
cause the waveform to exceed the maximum amplitude and clip.
¥ Normalize, by raising the waveform amplitude to the maximum,
puts the signal in danger of being clipped if you subsequently apply
a command or effect that boosts the signal slightly. If this occurs,
you may have to back up and apply 3dB Quieter to the normalized
signal before the other processing.
¥ Each application of 3dB Quieter erodes the signal structure
slightly; you cannot repeatedly apply 3dB Quieter, then use 3dB
Louder. to return to the original waveform.
¥ Due to the nature and limitations of digital audio, the sum of all
audio signals played together (including the effects of event velocity)
cannot exceed the waveform amplitude limit. Even though no
individual event is clipped, the combination may cause distortion.
If the selection contains any loud signals, Normalize may not seem to
have any effect. This is because the volume increase is determined by
the loudest audio in the selection. If an audio event contains segments
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