The Multichannel M

Multichannel mix formats extend the sound field beyond the frontal boundaries of a two-channel mix to include additional rear channels (Ls and Rs), a discrete center channel (C), and an LFE or boom channel. These additional channels are used to develop the mono, stereo, and surround components that constitute the multichannel sound field (Figure 11.3).

Stereo imaging produces a phantom image (the sense that sound is coming from the center even though there is no physical center speaker present). In 5.1, a physical center channel is provided that creates a discrete output occurring in the same position of the phantom image (Figure 11.4).

The surrounds (Ls and Rs) are often used to reproduce ambient elements and to facilitate front-to-back panning effects. The LFE (low-frequency effects) channel is a unique one created for the pur- pose of carrying low-frequency effects such as earthquakes, explo- sions, and vehicle rumbles. LFE signals are boosted by an addition- al 10 dB and equalized to remove all frequencies above 120 Hz.

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The LFE is an optional channel for consumer playback systems; therefore, any LFE content essential to the narrative must also be present in the main loudspeakers, as well.

I. Multichannel Panning

Panning is to the film mix as staging (blocking) is to theater. Panning is either fixed (static) or dynamic (moving). Fixed pan- ning promotes stability in the mix and is used to support static visuals or ambient elements. Dynamic panning is used to main- tain perspective with visuals moving on-screen. Off-screen panning and flown effects are supported by multichannel mix formats such as Dolby SR. Flown effects utilize all of the available full-range loudspeakers.

1. P

D

5.1

Dialog carries different information than that found in SFX and music. Michel Chion categorizes dialog as semantic (linguistic) while Walter Murch refers to it as encoded (perceptual). Regardless of the terminology, theorists generally agree that additional cogni- tive processing is needed to derive both literal and implied (sub- text) meaning from dialog; consequently, audiences focus on the content rather than the placement of dialog in the mix (panning and volume). This explains, in part why dialog is routinely panned to the center (Figure 11.5A) and volume levels are kept fairly con- sistent regardless of camera angles. In some situations, however, additional panning options are appropriate.

For example, the stereo (L and R) channels are often used for narration or voice-overs, providing additional contrast between nonsync and sync dialog (Figure 11.5B). Walla is often treated as Designing Sound for Animation

146

FIGURE11.3. The sound fields.

an ambient element and panned to the surrounds (LsRs). Dialog is often included in the screen channels to provide additional cov- erage for larger theaters (Figure 11.5C). Perspective and off- screen panning are used when the panning position is an essen- tial component of the narrative (Figure 11.5D). An extreme example of perspective panning can be heard in the film Casper where the voices are flown (Figure 11.5E). Dialog is rarely included in the LFE. One notable exception can be heard in the Walt Disney feature Aladdin; in this example, the cave is person- ified with an omnidirectional voice carried (but not exclusively) in the LFE.

2. P

SFX

5.1

Sound effects are typically panned to reflect the on-screen objects or to suggest off-screen movement (Figure 11.6A and B). The addi- tion of the center channel (creating a LCR subpath) helps to smooth the transition of dynamically panned effects moving from left to right in the front channels (Figure 11.6C). In some cases, SFX are panned dynamically between all five full-frequency chan- nels (flown effects; Figure 11.6C). An undesirable panning conse- quence known as the exit sign effect can occur when hard effects, placed discretely in the surrounds, draw the audience’s attention away from the screen.

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Unlike dialog and underscore, sound effects are routinely panned dynamically to follow the objects they represent. When panned dynamically, sound effects enhance the perception of motion and spatial perspective implied on-screen. Sound effects are often used as transitional devices. By creating subpaths within the 5.1 channel configuration, SFX can be dynamically panned discretely to and from specified channels (Figure 11.7).

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FIGURE 11.6. Panning SFX.

3. P

A

5.1

Ambience helps to define the boundaries of the mix and is routine- ly panned to any and all available channels (Figure 11.8). When ambience is panned in the screen channels, the audience can be made to feel like spectators. When ambience is placed in both the screens and the surrounds, the audience feels as if they have been placed within the scene. It is not unusual to place separate ambi- ent elements in both the stereo screen channels (LR) and the sur- rounds (LsRs).

4. P

M

5.1

In multichannel formats, the music for title sequences often uti- lize all available channels for maximum coverage and impact (Figure 11.9A). Then, as the narrative begins, the placement of the score is reduced to stereo (L and R). Underscore is traditional- ly placed in the stereo screens (Figure 11.9B). Source music (mono) is often panned to an on-screen or implied perspective (Figure 11.9C). Chapter 11 POSTPRODUCTION 149 FIGURE11.8. Panning ambience. FIGURE11.9. Panning music.