The Sound Of Star Wars

Science World, May 10, 1999 by Maria L. Chang

HOW DO YOU CREATE SOUNDS FOR A FANTASTIC UNIVERSE?

A sneak moment from this summer's blockbuster movie The Phantom Menace, the latest installation in the, Star Wars saga: Jedi knight Obi-Wan Kenobi (left) duels with the evil Darth Maul. Their sword-like lightsabers flash and sizzle as they clash. The warriors lunge at each other, yet their footfalls are barely audible on the metal floor.

Now imagine the same scene--but instead of the lethal buzz of lightsabers, you hear cracking wooden sticks. Instead of the thud of fighters' leaps on metal, you hear thumps on a creaky wooden stage set. Sound like a big yawn?

Just as dazzling visual effects turn a sci-fi fantasy movie into near-reality, sound effects add the finishing notes. In the past few years, powerful computers, advanced software, and synthesizers (keyboard-like instruments that produce electronic sound signals) have elevated sound effects to new heights. After all, how believable is a computer-generated invading army of androids when you don't hear a single stomp or whir?

MAY THE SOUND BE WITH YOU

Whether or not you're aware of it, sound plays a key role in how you perceive reality. Picture a scene where a solitary car races down a stretch of empty highway. But what you hear is the churn of motorscycle. Your brain instantly alerts you to the fact that what you hear doesn't match what you see. In other words, your senses are in conflict--a phenomenon called cognitive dissonance. In a movie, this would immediately distract a viewer. Popcorn time?

Directors know that realistic sound is vital to hooking an audience. But what do laser cannons or a mobbed alien marketplace sound like? This was the challenge faced by The Phantom Menace's sound designer Ben Burtt.

SOUND BYTES

Burtt and his crew created up to 1,300 new sound effects for The Phantom Menace. "Each sound is for a specific weapon or a particular robot's head revolving around," Burtt says.

You might think the best way to create extraterrestrial sounds would be to invent them on synthesizers and computers. But Burtt's most essential tool is the common tape recorder. "The style of Star Wars has always been to use an organic soundtrack," says Burtt. "That means we collect real sounds that exist out there in the real world. We'll go out and record racing sports cars or a roaring aircraft."

Burtt's secret trick is to alter recorded sounds so they're not recognizable. How? After recording the thrust of a speeding plane, for instance, Burtt rerecords the sound into a synthesizer, which converts the sound signal into a digital signal of 1s and Os. A plane engine's sound is normally high-pitched and whiny. Pitch is how high or deep a sound is and depends on the frequency (the number of complete vibrations of a wave in one second). The higher the frequency, the higher the pitch.

Using the synthesizer, Burtt lowers the frequency and deepens the engine's pitch. "It still sounds powerful, like a vehicle roaring along, but you don't recognize it as a World War II fighter plane," he says. Add an explosion or thunder to the sound, and you've got a booming spaceship.

BACK TO BASICS

Say the spaceship accelerates across the screen to jump into hyperspace. Would it maintain a steady sound? Not really.

Think of a wailing fire truck speeding by. As the fire truck approaches, the siren's frequency increases and its pitch rises. As it passes, the frequency decreases and the pitch drops. This phenomenon is known as the Doppler effect (see below). New computer software easily simulates the Doppler effect. Programs alter the pitch so you get the sensation of an object flying by at breakneck speed.

But there are more imaginative ways to create the same effect. Take the motion of Star Wars' lightsaber, for instance. Believe it or not, its sound came from the motor of an old movie projector and a sputtering TV picture tube. Combining the two sounds produced the humming tone of a steady lightsaber. But to simulate a swinging lightsaber in a duel, Burtt played the original sound over a speaker, whipped a microphone past the speaker, and rerecorded the resulting whish. "You get a big Doppler shift in the sound, as if it's a sword swinging through air," Burtt says.

Creating all the sounds necessary for The Phantom Menace has taken Burtt and his crew about three years to complete. Was it worth it? The audience's ovations will tell.

COMING SOON TO THEATERS: 3-D SOUND

Sound designers Ben Burtt and Gary Rydstrom labored for more than three years to create the fantastic sounds in The Phantom Menace. To ensure that the soundtrack doesn't sound fiat in theaters, LucasFilm THX and Dolby Laboratories created Dolby DigitalSurround EX, a new movie sound format (see right).

Surround EX, which will debut in theaters at the same time as The Phantom Menace, adds extra speakers and a rear sound channel on the back wall. (Current Surround Sound systems separate sound into left; and right; channels, so you hear sounds move from one side of the screen to the other.) "I wanted to develop a format that would place sounds exactly where you would hear them in the real world," Rydstrom says. With Surround EX, audiences can actually hear a plane, for example, fly around them.