I know they can add audio in post by Foley artists, but how do they keep sounds of equipment, people, or other background noise that isn’t wanted out of the movie?
I’m especially curious about older movies that were made before the rise of digital audio.
In: Technology
If it was too loud, they did ADR. A majority of films from the 60s and earlier did this. The original track was very noisy and useless because the cameras were very loud, but used as a guide for the actors to dub their voice over it.
Then there was analogue gear that could reduce noise in the background, and later with SFX it sounds great. (Think of being on a busy street in NY… ) The BG noise would be mixed with sound fx, and have a “compander” to pull down the bg noise when a voice wasn’t prominent. This is the whole purpose of a ***dialogue editor***, they make sure the dialogue/background are mixed to sound coherent.
ETA: cameras were very loud
You don’t need digital audio to be able to edit audio. From the start audio was not attached to the video; the first movies had no audio except for musical accompaniment that was actually played live by someone during the viewing!
Later on you could record the actors with directional microphones on poles held just out of frame. These “boom mics” are still used today and you can sometimes see errors as they slip into the edge of a shot. If you can get clean audio of their performance then you can add extra sound effects later.
Finally the equipment, people, and other background noise is just minimized. Ever hear the call “Quiet on the set!” before? That is to minimize the amount of noise that could contaminate the audio and ruin a take.
Microphones.
Microphones are designed to pick up sounds. And by changing the design of the microphone, you can modify the area where the microphone picks up sound.
The most basic kind of microphone is *omnidirectional*, which is pretty much what you’d think it is: it picks up sounds from all around, pretty much equally. This is probably the type of microphone your phone has, as well as the type of mic that’s built into your camera. The quality isn’t great, especially at any kind of distance.
Another type of microphone is the *Cardioid*. This picks up sound mostly in front of the mic, some from the sides, and very little from behind itself. If you see someone with a handheld mic, like a news reporter, that’s probably the style they’re using: when they’re holding it in front of themselves to talk, you mostly hear them. When they extend it to someone else, you’ll hear that person, but not much else.
The third common type of mic is the uni-directional mic, sometimes called a “shotgun” mic. This will pick up sound **only** in a very narrow space in front of the microphone, and only fairly close. If you pointed one of these mics at a person talking to other people in a big group, you would only hear the person the mic is pointed at.
Microphones also can use wind screens and other similar audio-baffles to cut down on unwanted sounds, but the big element is the type of microphone used.
If they record on location then they usually use directional mics that only capture the person speaking the lines. That’s why you see those mics on a stick being held directly above the actors sometimes.
Everything else is added in the edit bay. Even the lines are sometimes re-recorded in the studio, that’s called ADR.
For background sounds/noise they sometimes just record empty rooms and spaces so they have that steady ambiental sound of the space itself, and then they layer sound effects and dialogue on top of that.
Of course there’s been pre-existing libraries of those kinds of sounds for decades so you don’t have to record them for every film.
If you want to see/hear an amazing example of what they could do with analog technology, watch the ‘Telluride’ version of Touch of Evil. The sound in the opening scene is fantastic.
Movie audio is rarely recorded live. It is recorded in a controlled environment at an audio studio and composed together, then played alongside the video.
If you look at a behind the scene photo of almost any movie, you’ll see a guy holding a long pole with the main microphone on it. He’s holding the mic _just_ above the camera frame on the boom pole so that the microphone is as close to the actors as possible. Just getting the mic super close to the actors means the actors are relatively louder than the other noises.
They will repeat a scene over and over again if something happens during a take that is loud enough to be a problem. Sound stages are often miserable because they turn off a lot of stuff like the air conditioning when doing takes to reduce the noise. A real coffee shop is near a street and a lot of cars drive past. A film set fake coffee shop is on a studio lot, away from traffic. And when possible, they shoot on fake sets on sound stages that are buildings with some amount of noise dampening in the walls, and not a lot of equipment that isn’t under the control of the film that they can turn off. There’s no refrigerator in the sound stage for example — lunch is in another building.
The microphone on a boom pole is usually a shotgun mic, which is a type of microphone designed with two pickups in it so it mostly picks up sound it’s pointed at, and doesn’t pick up as much sound coming from the sides.
There will often be secondary additional microphones hidden in the set. Sometimes they get hidden behind a potted plant, so they are called “plant mics,” but they can potentially be closer than the boom mic. On modern productions, there are small “lavalier” mics that are small enough to be hidden in the costume and worn on the actor’s body so they can be just a few inches from the actor’s mouth. One scene will secretly be flipping between tracks recorded on different microphones if one picked up a distracting noise and another didn’t.
Sets are designed with a lot of soft carpet to muffle footsteps. If you ever watch “Star Trek The Next Generation,” from the 80’s/90’s the space ship is covered in beige carpet instead of having metal and plastic industrial “space ship” looking floors like a real world warship. The modern spinoff Star Trek series now have flashier shiny floors partly because the actors now wear those body pack lav mics and it’s easier to filter out footstep noises than it used to be.
Background music helps cover up a lot of little muffled noises. You ever hear the music swell at a kind of random moment when it doesn’t seem like the most emotionally motivated story beat? Maybe a car drove past while they were shooting, and they just cranked up the music a little louder for a bit so you wouldn’t notice.
A LOT of films were (and still are) shot “MOS” — That’s the industry term for silent. It’s the acronym for “Without Sound” in german.
According to friends in the movie industry, the movie El Mariachi (Robert Rodriquez) is a perfect example. It was shot MOS on a budget of about $7000 over a few weeks (basically a student film). Then it was sold to a distributor who spent a million dollars and two years adding sound to it, including actors voices.
Photography is only one part of the movie making process, and not always the most expensive part. Editing alone can cost more than the photography did.
This question has a very interesting answer because this has been a problem ever since movies first started having sound and despite the years of innovation when it comes to filming and recording equipment the situation today is not much different than what it was nearly 100 years ago, with many of the same hurdles being overcome with the same solutions.
For starters unwanted sounds are a big problem for productions so ideally they want to have next to no sounds because it’s easier for them to add sounds in post production. That means that nearly every sound you hear in a movie or TV show, even mundane ones like a character closing a door or walking, are often added in post. Prop departments have a wide range of silent props meant to look like real objects but without being as loud. Think paper bags, ice cubes, cue balls, tableware and all other sorts of things usually amde of rubber, so that they don’t make loud noises during filming. They often also add special soles to shoes so that they’re quiet when actors are walking. Secondly they use a wide variety of sound recording equipment and many different kinds of microphones. If you’ve ever wondered why there’s always that one guy holding a mic on a boom just out of frame, often causing the classic blooper of the mic dipping into frame just for a moment, it’s because when recording dialogue they’re using microphones that only pick up sound from very close to them, so they’re held just above the actors to pick up dialogue without also picking up a bunch of ambient noises as well. Actors often wear hidden mics or mics are hidden in props around the set, like in flowe vases on a table or objects near the characters. Ideally you want dialogues to exist on completely clean tracks with no ambient noises. This still gives movie productions problems as there is often no convenient way of hiding a microphone or keeping out ambient noise and it requires very creative solutions.
Lastly the only major difference between the past and now is that we have digital technology that can, in a pinch, try to edit out an unwanted sound. If they cannot record a scene again this is the last resort. Overall the actual sounds being recorded during filming are few and far between, mostly being dialogue or some select sounds the filmmakers want to be part of the scene for authenticity. Practically everything else, from the sound of objects around the actors, the spaces they inhabit, their shoes on the ground, their cups on their lips, theor clothes, their keys, aaaaaaall that is recorded separately by foley artists and added later.
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