SFX + Six Channels = a Roomful of Sound

Surround Gives Sound Effects a New Dynamic

Sound mixers need to become comfortable with multi-channel sound effects — because viewers already expect them. That means not only figuring out the best way to convey spatial relations across 5.1 channels, but also getting ready for some new investments in processor power and storage space to handle the ever more granular demands of SFX mixing.

"The DVD market is heavily influencing the evolution of sound effects on television," says Jonathan Porath, managing director of New York post facility Sound One, which does surround-sound design for both film and TV. "What used to be just in the theater is now in the home theater."

The need to spread sound effects effectively around a surround sound field is forcing new dimension into TV audio. "In stereo, you can use a couple of layers of sound effects to fill the space, and that’s plenty. In surround, you need multiple layers because each element has so much space around it in its own channel," explains Porath.

Andy Kris, lead mixer at Sound One for HBO’s The Wire, puts that theory into practice. "To get the sound as dense as it would be in stereo requires a lot more sound layered in," he says. Gunshots, for instance, are given added dimension by using the production sound to trigger gunshot samples from the facility’s central SFX database. Those samples are spread in stereo while the production sound is placed in the center channel. Reverberation from a T.C. Electronic TC6000 is positioned in the surround channels to create an ambient envelope. The rest of the processing is done via Pro Tools|HD plug-ins, including Metric Halo’s Channel Strip and Digidesign’s Reverb One and Revive convolution reverbs.

Another example of surround SFX on The Wire is the use of what Kris calls "loop groups" for the knots of drug dealers that cluster on street corners in scenes in downtown Baltimore. These are walla-type stems — indistinguishable murmurs and snatches of conversation — with keywords denoting which type of drug each group is selling. Kris, using Digidesign’s ProControl, will pan them around the soundscape, nesting the primary dialog in the center channel. "You get the effect of chaos, but [you] never have the dialog compete for the viewer’s ear."

Like many of HBO’s series, The Wire has developed an avid core of fans, and, says Kris, surround sound effects are another way of involving critical viewers. "The layers are aimed at the fans," he says. "They’ll watch an episode five or six times, and each time they do they’ll notice some additional cues from the sound effects channels. The show has no score at all, so the sound effects elements are used to tell part of the story."

Kris will use surround channels to expand the sense of scale of the set on The Wire. "When the police raid a house, we’ll put enhanced sounds of them rummaging through different rooms into the surrounds," he says. "It creates a sense of chaos that you couldn’t pull off with location sound and that stereo can’t do justice to. When those sound effects are in surround, it feels like they’re in a much larger house than the set would suggest."

It’s a Scream

The Creative Group in Manhattan posts for HD channels such as InDemand. (In October, it launched its own HD channel, Scream TV.) Senior sound designer and mixer Troy Krueger says discrete multi-channel surround has demanded some unique processing techniques for sound effects. "I hear people putting effects into the front and rear channels simultaneously, as though it was just another kind of stereo spread," he notes. "But when you excite the front and rear speakers at the same time, you get no sense of depth or dimensionality." The solution, he says, is to put the dry, or unprocessed, effects into the front stereo pair. The same signal is then fed to a reverb processor with 30 to 60 ms of pre-delay dialed in. "The result is that you hear the initial attack of the effect in the front speakers, then the effect with processing on it milliseconds later in the surround channels. This approach [establishes] time and space — the cues that people use to establish a sense of place in their minds. You could never do it as effectively as this with stereo."

Krueger’s sound effects are stored on a 5 TB central RAID server. Increasingly, he and other post mixers turn to dedicated 5.1 sound effects libraries from companies including Renaissance, Urban Atmospheres and Immersion, which provide ready-to-wear multi-channel effects. But the field is still a DIY environment. Mixers will create layers and stems in six channels, piece by piece and pan by pan. "And when we’re not crunched for time — which is rare — I’ll go back over them and print them to Pro Tools as files on a single I/O," says Krueger. That keeps the finished sound effect intact, but still allows its pan relationships to be adjusted to suit the next application.

This technique will also eat up exponentially larger amounts of storage space and processing power. Many mixers familiar with surround expect that multi-channel SFX are going to drive industry platforms to integrate faster processors and to spur implementation of TB-scale server systems.

Cinema Meets TV

Rex Recker, co-owner and mixer at audioEngine in New York City, says the proliferation of digital television is driving a convergence of broadcast and cinema techniques for surround effects mixing. He just finished mixing a series of spots for Microsoft’s Xbox, which were to be shown first in theaters and then on television with the same 5.1 audio mix.

Recker notes an interesting disparity between cinema and broadcast surround. Dolby specifications call for the surround channels in multi-channel film sound mixing to be done at 82 dB; for television broadcasting, the spec is 82 dB in the LCR and 85 dB in the rear channels. "For whatever reason, the surrounds are a little hotter in television," he says. That changes how viewers hear the mix — particularly the effects, which tend to be transient, spiky and perceptually louder. Recker also uses Sound Miner, a sound effects database manager application that comes bundled with Pro Tools and allows him to manage the facility’s growing database of stereo sound effects. He converts them to 5.1 using the quad panners on the Pro Controller. "Stereo effects are good in 5.1 as static ambient effects," he explains. "When you want something that’s going to whip around the room, that will be a mono effect."

Giving NASCAR Some Gas

At RainMaker, a post house in Richmond, VA, specializing in sound design for spots, sound designer Jeff McManus says a recent series of eight spots for NASCAR illustrates how multichannel manipulation can change the nature of audio elements. Car-engine sound effects are fairly stock stuff, although there are nuances differentiating the buzz of 1950s cars from the roar of more recent models. Using his ATC LCR front array and the rears, however, McManus gives them new dimensionality. "We add sound effects, like jet engines, but the real effect comes from the perspective we get by moving the cars through the speakers as they move across screen," he explains. Just as a car reaches the apex of perspective — the Doppler midpoint — McManus adds a whump! from a bass guitar to punctuate the move. In pit stops, the pneumatic lug guns are in the rear channels, putting the viewer in with the pit crew.

Surround actually allows McManus to use music as a sound effect, he says. The campaign’s theme song, Boston’s "Long Time," starts with an organ fugue that the mixer put through reverbs and delays before routing it to the rear speakers. "It gives you a swirling, sound-design sort of effect, but without disguising the song," he says.