Apple Soundtrack Pro 3 - Manual (Page 351)

Placing Stereo Music in a Surround Mix
The simplest option for stereo music in a surround project is to just leave it in stereo. If
you just use the stereo panner for a music track, the left and right signals remain in their
respective channels. However, some surround mixes include a hint of music in the rear
channels as well. With the Surround Panner HUD, you can place the right music channel
somewhere between the right front and right rear position, with more emphasis on the
front speaker. Do the same with the left side and listen to the mix. Make adjustments as
needed.
Using the Center Channel
In a multichannel system, there are three ways to achieve a centrally placed sound image:
Create a “phantom center” (mix sound to the left and right equally, as with stereo)
This is a common strategy, but it assumes the listener is seated exactly between the
speakers. The timbre of sound is not the same as from a direct speaker because of
cross-cancelation effects.
Use the center channel alone
This creates a stable center image for listeners in any location. (To prevent the audio from
sounding too focused or narrow, its reverb can be spread to the left and right channels.)
Use all three front channels equally or in various proportions
This method allows for greater control of the range of spatial depth and width. The
phantom center can be reinforced by additional signals in the center channel, which can
be enhanced by signal spread into the left/right pair. The disadvantage is that sound
from all three speakers may not blend well or may not arrive at the listener at the same
time, causing side effects such as comb filtering, shifts in tone color, or smearing. To
counteract these side effects, you can first process the additional signals to change their
spatial character, timbre, or prominence relative to the main center signal.
Using Surround Channels
Subtle surround effects can greatly enhance the listener’s sense of depth compared to
conventional stereo. Popular music often benefits from creative use of surround. But
don’t overdo it. The film industry guideline for visual effects applies equally well to
surround effects—don’t let effects distract the listeners from the story.
Using Surround Effect Plug-ins
Soundtrack Pro includes a collection of professional surround-specific effect plug-ins for
shaping your surround mix, including Surround Compressor, Delay Designer, Space
Designer, and Multichannel Gain.
For a complete list of these true surround effects and a full description of each, see the
Soundtrack Pro Effects Reference document, available in the Help menu. For information
about using processing and realtime effect plug-ins, see
Working with Audio Effects .
351 Chapter 13 Mixing Surround Sound