Los Angeles -- There's an episode of the old "Batman" TV series in which a villain ties Robin to the clapper of a giant clock bell. When the clock is to toll at midnight, the sheer cacophony of the ensuing gonging is supposed to spell a particularly gruesome auditory doom for the Boy Wonder.
Not to suggest that the makers of "Batman Forever" have plotted the same fate for moviegoers, but certainly, if you see and hear the movie in the right theater, the experience can be akin to hanging out in that bell with the Caped Crusader's hapless sidekick.
When the Batmobile roars to life, "You can physically feel the sound waves surrounding your body. You're in the car," says Peter Macgregor-Scott, producer of "Batman Forever."
"Batman Forever" is hardly the only summer film that allows audiences to revel in the art of noise. Already in theaters are "Die Hard With a Vengeance," in which huge chunks of New York City are blown up in eardrum-wobbling Dolby Stereo, and "Congo," offering the ostensible delight of killer monkeys getting ripped // apart by laser guns while a volcano erupts. On the way: "Apollo 13," which brings you close to a rocket's liftoff, and "Judge Dredd," which posits a grim future as, if nothing else, extremely loud.
As an example of the work that goes into creating the perfect sound mix, Mr. Macgregor-Scott points out that to get the Batmobile noisy enough, "We used 60 separate tracks. Some of our guys went to Rocketdyne and said, 'We'd love to record a jet engine.' They said, 'Sorry, we don't permit film crews here.' They replied that they were creating the sound for the Batmobile, and they said, 'Come on in, boys!' "
To get Gotham City to sound its best, Mr. Macgregor-Scott brought in the team nominated for sound engineering Oscars on his previous productions, "The Fugitive" and "Under Siege." For the famous train crash sequence in "The Fugitive," 240 separate sound effects tracks, four or five dialogue tracks and 48 tracks of music were mixed together in three minutes of film. "The Fugitive" employed a staff of 100 for the film's sound; "Batman" used slightly fewer.
Time for a quick listening lesson: Sound, measured in decibels, is first discernible to the human ear at roughly 20 decibels (roughly the sound of a feather brushing the ground). Normal conversation measures about 75 decibels, while conversations in movies -- those on screen, not the loudmouthed louts sitting behind you -- weighs in at 85 decibels. Noise can become harmful to the human ear around 130 to 160 decibels if held for sustained periods. Movie cacophony at its loudest is designed to be played between 110 and 120 decibels, and then for only fractions of a second at a time.
Along with the Batmobile, the highest decibel reading in "Batman Forever" comes when Tommy Lee Jones, as Two-Face, shoots off a gun in his lair and the sound ricochets around the room, good enough for a momentary 115 on the decibel level. But that's a high-end sound effect, not the gut-rumbling bass of Batman's wheels.
"Before the digital world, before Dolby, such gunshots would snap the speakers," Mr. Macgregor-Scott says. "You could never get the full range, because the speaker couldn't handle it."
"We in the film business have historically been 15 years behind the record business in terms of audio sophistication," says Dennis Maitland, a sound mixer ("Die Hard with a Vengeance") whose work has earned two Oscar nominations. "Now, we're still behind, but we're coming up in leaps and bounds."
Technology has allowed sound mixers such as Mr. Maitland to capture even the quietest of sounds amid the mayhem of an action film. While working on "Die Hard with a Vengeance," he offered to bet star Bruce Willis their respective homes that he could record logistically difficult scenes without any dialogue needing to be re-recorded in post-production. Mr. Willis declined the offer; Mr. Maitland says he would have won.
David MacMillan, sound mixer on "Apollo 13" and part of the Oscar-winning sound team of "Speed," says some of the rocket take-off effects came from tracks provided by astronaut Dave Scott, a technical adviser on the film.
"They were recorded by NASA, and we heard what taking off sounded like with a lot of noise the public doesn't hear," Mr. MacMillan says. "We actually matched or used parts of the tape to create the feeling of what it was like in the capsule itself."
Back at the theater . . .
Still, all this work, and then the theater's sound system can mess it up.
"We send theaters a reference tone that they can align their equipment to, but they can play it so low you can't hear everything or so loud it's irritating," Mr. Maitland says. "Sound works in an almost subliminal way -- if you have difficulty understanding people on screen, the minute that happens, you're out of the movie, out of the make-believe."
"I saw 'Speed' twice last year, once in a good theater, and once not," Mr. MacMillan says. "The difference in the soundtrack is amazing. It's pretty disappointing to hear a movie through a bad sound system. It makes you realize how most theater operators feel that sound is secondary, when it's obviously part of the whole experience. It really pays to see a movie in a first-class theater."
How to choose that first-class theater? There are three maiformats: Dolby Stereo and Dolby Stereo Spectral Recording (SR) both play in two-track stereo. Dolby Digital is six track, surrounding the theater and offering plenty of "boom." And Sony Dynamic Digital Sound (SDDS), which plays in both eight and six tracks.
According to Mr. Macgregor-Scott, Sony Dynamic Digital Sound can be the most dynamic, but there aren't enough theaters that can accommodate the eight-track format. Thus the sound is automatically "folded down" into six tracks.
Therefore, Mr. Macgregor-Scott says, the most reliable is Dolby Digital, because it's "true six-track, absolute perfection."
The difference between a theater with a six-track Dolby Digital sound system and one with a two-track SR system, Mr. Macgregor-Scott says, "is like listening to a $20,000 stereo system down to a boombox."