Eliminating background sound

[Thomas Theron Cooper]

I'm planning a shoot in a room that will probably have some background noise. There is a window and occasionally there are birds chirping and the odd car honking. What is the best way to eliminate the background sound? Is there a software you can recommend to enhance the sound. I was hoping I could capture good audio and then filter out the frequencies or something, keeping sound beyond a certain level. I'm very new to this. I want to manage the best possible location but hiring a location just adds to the uncertainty and cost. This is a free location. I have access to a Rode Videomic pro, a Sennheiser lav mic and a Zoom H4n. Please give me some guidance. Thanks.

 

[Bruce Watson]

What is the best way to eliminate the background sound?

Record in an anechoic chamber? But if you did, you almost certainly wouldn't like the result.

Outside of an anechoic chamber you can't eliminate all background sound (noise). What you can do, is increase your signal-to-noise ratio. There's a vast array of things you can do to accomplish this, but it comes down to two basics. First, do what you can to suppress the noise so that what you have to record is recorded at very low levels. Second, do what you can to increase your signal, which is mostly about mic placement and technique, to make sure your signal is recorded at maximum safe levels.

Good audio is more difficult than good video. It's really not very intuitive at all to most people. There's books written about it; time to get reading.

Is there a software you can recommend to enhance the sound?

Another topic that has books written about it. Without your being more specific about what "enhance" means to you, no one has any idea how to answer.

If you're still talking about noise "removal" then no -- what you're asking is sort of like asking how to remove the salt from that cake you just baked. If you don't want that level of salt in the cake, don't put it in the batter. Which is the answer you aren't looking for -- if you don't want the noise in the final result, don't record it.

A good clean capture is worth it's weight in gold. When you consider what it might take to clean up a bad capture, mere gold may not be sufficient.

 

[Jema]

There are software that can reduce background noise to a certain level (noise reduction like Izotope RX and multiband gates like C4), but they are pretty expensive if you don't do a lot of post audio, and they can be quite tricky to use if you're a novice (especially if you don't have a good monitoring system). A common mistake is to overuse them which affects the sound quality.

The best way is to follow Mr. Watson's advice, and for future shoots, remember that choosing a quiet location is among the best things you can do to get good sound (after hiring a professional of course).

 

[Noiz2]

Forget about "fixing it in the mix". It's possible to do amazing things but not always and you won't know if your a luck one till post, and then it's too late. Plus $75 an hour (or more) for someone who has the tools and knows how to use them will quickly make location costs seem cheap.

SO, listen and don't shoot when sounds you don't want are happening, or reshoot if they surprise you. Pick a location where the sound you can't avoid will be OK if you can't get rid of it. If your in the city you will hear some traffic, as long as it's not too specific and is just a "city roar" it's probably fine. If it makes sense that there might be birds out side the room in your story then don't worry too much about them, as long as they are not dominating the track.

Other wise you can do things like put storm windows on, that will greatly reduce outside noise. If you don't see the window in the shot you could put a piece of plexi on the inside also.

Shoot at low traffic times to cut down on car noises. Shoot when the girds are quiet. If you can fake the daytime look (as in you don't have shots out the window and or you can stick some lights out side the window) shoot night for day. There is very little traffic at three am and the birds will all be asleep.

 

[hscully]

It's tough on locations. We were in a cafe and the refrigerator was loud. On every take we would unplug the refrigerator and then plug it back in so the food in it would not spoil. Suffice it to say, this is an "error-prone" operation We had a couple of takes we wanted to use the take for performance but it had the darn refrigerator in it. I used noise reduction in Adobe Audition to remove a refrigerator sound and then fill in the background with room tone sans refrigerator. It's hard to get right. Too much noise reduction and you get that awful flangey digital sound, that is quite useless.

So it worked on one take and I could not get it to work on another. Finally we had the actors come in and ADR'd those takes.

Noise reduction can work but it's a time consuming proposition and ADR is costly in time and effort. The absolute best thing to do is listen to these guys and get quiet locations, and where you can't, monitor the sound closely. Anything that is not "ambient" like a plane or a motorcycle going by, that will not cut needs to be considered a blown take and you have to go again. It's costly to have to do takes over too but it's better than using noise reduction

Oh... and consider the value of short takes

One thing I've found on locations is that weekends are definitely louder and busier than week days. If you schedule potentially noisey locations for a weekday, you may have better results. Leaf blowers! Arrrrgghhhhh!

 

[Rick R]

Shutting down noise making appliances is SOP. Aircraft are another story, which follow me around.

 

[clang]

Totally agree with above advice re preventing the problem during production if at all possible. Never plan to 'fix it in post' unless you know in advance you'll have insurmountable problems at shoot time - something to discuss with the director etc. (E.g. some movie shoots know that can't record live sound at some noisy locations, so plan in advance to ADR all dialogue afterwards.)

You mention "birds chirping and the odd car honking" - why are they a problem? If e.g. the project is a Victorian drama, then I understand that car honking would be an issue. But if it's just inconsistency/continuity you're worried about, then there are ways around that. e.g. I had a short film shot unavoidably during cicada season, so had random insect chirping in the background in many shots. I separately recorded some 'ambient noise' of just the cicadas at the same location, then slotted that into the film in post whenever it was needed to disguise 'chirping continuity' problems

 

[Noiz2]

Probably should point out also that how hard it is to deal with erant ambient sounds on the dialog track also has a lot to do with how much sound post you are going to do.

Big stuff like planes are always a problem but things like birds could be a pain if you are essentially doing no post and trying to just use production. But are much less of a problem if you are doing a real sound post and your adding in five or six background layers and a bunch of FX tracks. Once you fill in the sound track much of the little stuff like birds just blend in to the mix and go away. Of course if there should be no birds you are back to it being a problem.

Same with traffic. If it's just a car or two AND you are really doing sound post AND it's OK for a car to be heard, then you can just fill in the parts that got chopped in the edit and you will get the added bonus of making your edits disappear.

 

[Ron Evans]

You can remove a lot of these annoying sounds with Spectral Layers from Sony Software. There is a reasonable learning curve but it works well. I have used successfully to remove mic handling noises etc.

Ron Evans

 

[morgan_moore]

You don't say what you are trying to do. All of that ambient can build a visual picture of your location.. but would not be great for talking head on a greenscreen for example

 

[dp90068]

Use the best mics you can afford including a shotgun like a Senheiser 416 or Sanken Cs1e, learn about mic placement, and use a good pair of headphones. The more work you do the more you learn about what you can get away with.

the background sounds you describe are usually not a problem.

I remember one time we were doing interviews on the lawn at the Pentagon and a plane went by so close overhead I could practically see the tire treads. After the interview the reporter turned to the soundman and said, "how was the sound with the airplane?" The soundman said, "What airplane?" .....

 

[Thomas Theron Cooper]

First, do what you can to suppress the noise so that what you have to record is recorded at very low levels. Second, do what you can to increase your signal, which is mostly about mic placement and technique, to make sure your signal is recorded at maximum safe levels.

I'm hoping this will make it work for me.

..Another topic that has books written about it..

I tried going over a couple of books on sound. It is clearly a very complicated subject. Some topics would go over my head.

There are software that can reduce background noise to a certain level

I'm new to this and don't have the budget for a sound guy. I'll find out if this is something feasible for me.

You don't say what you are trying to do. All of that ambient can build a visual picture of your location.. but would not be great for talking head on a greenscreen for example

What I'm filming is a talking head against a background. So I really want as little noise as I can get.

You can remove a lot of these annoying sounds with Spectral Layers from Sony Software.

I'll try that!

@Noiz2 What you say would work for a short film or a feature. This is a talking head against background shoot. So I need to eliminate all noise as far as possible.

You mention "birds chirping and the odd car honking" - why are they a problem?

..It's because it's a talking head, with no other activity happening.

Use the best mics you can afford including a shotgun like a Senheiser 416 or Sanken Cs1e,

I have a rode videomic pro and a sennheiser lav. I'll look into those mics.

Thank you everyone for the quick response and some really useful tips! Really appreciate it. I'll do a test shoot and see how it turns out. Will try to get hold of a good book and look into the software mentioned.

 

[Richard Crowley]

If you are shooting "a talking head against a background. So I really want as little noise as I can get." then why are you shooting in a noisy location? As has already been suggested, shoot in a quiet locatoin against a green screen and just put whatever background you want. It is ever so much easier to do in video than in audio.

I don't think you realize how difficult it is to "remove" noise after the fact. Perhaps you will have to experience it for yourself. If you read all the books on the subject, the bottom line would still be to minimize and ideally eliminate the noise while recording. There really is no magic here.

 

[David Jimerson]

Shutting down noise making appliances is SOP. Aircraft are another story, which follow me around.

Not too long ago, I was shooting, and an airplane starting getting close, so we quit. But it kept getting louder and louder, and finally it sounded like it was going to crash into the building. We stuck our heads out the window, and directly above us, low enough to see the bolts on the outer skin, was Air Force One.

 

[hscully]

While you're at it, take a gander at Barry's and David's excellent DVD Sound for film and television. They show a scene in a restaurant with excellent examples on how to acquire great sound. Get it right on acquisition and forget about "fixing it in post" is the clear message I'm hearing!

 

[Thomas Theron Cooper]

Thanks everyone. I'll try to work out the budget to hire a better location.

I don't think you realize how difficult it is to "remove" noise after the fact.

I realize how complicated it is. As I mentioned earlier, I picked up a book and all the theory about Sound, itself was too much for me to absorb. Some of it was too complicated to understand.

While you're at it, take a gander at Barry's and David's excellent DVD Sound for film and television.

I'll take a look. Thanks.

 

[David Jimerson]

While you're at it, take a gander at Barry's and David's excellent DVD Sound for film and television. They show a scene in a restaurant with excellent examples on how to acquire great sound. Get it right on acquisition and forget about "fixing it in post" is the clear message I'm hearing!

:beer:

Also, in the intro section, we illustrate exactly how to use the signal-to-noise ratio to do what the OP wants. A couple of different ways.

 

[Richard Crowley]

I realize how complicated it is. As I mentioned earlier, I picked up a book and all the theory about Sound, itself was too much for me to absorb. Some of it was too complicated to understand.

Note very carefully that there is a difference between "understand" and "accomplish". Even for people who completely UNDERSTAND the concepts, algorithms, techniques and tricks of removing noise after the fact, it is still EXTRAORDINARILY DIFFICULT to accomplish without causing audible trauma to the desired sound you want to preserve.

It doesn't take studying dozens of books and years of experience to figure out that you need to reduce (or ideally eliminate) interfering noise AT THE SOURCE! It is a deceptively simple concept. But that doesn't mean it is simple to implement. But it is ever so much simpler to avoid noise while recording than attempting to remove/reduce it after the fact.

 

[Thomas Theron Cooper]

It doesn't take studying dozens of books and years of experience to figure out that you need to reduce (or ideally eliminate) interfering noise AT THE SOURCE! It is a deceptively simple concept. But that doesn't mean it is simple
to implement. But it is ever so much simpler to avoid noise while recording than attempting to remove/reduce it after the fact.

Point noted! Thanks.

@David Jimerson Will go over it!

 

[Noiz2]

@Noiz2 What you say would work for a short film or a feature. This is a talking head against background shoot. So I need to eliminate all noise as far as possible.

Not necessarily. If it's that clean newsroom thing you are going for then you really should look at the green-screen option. It will come out better and take a LOT less time than trying to clean out noises in the ambience you don't want.

If it's a documentary though, often it's not a problem having some world in the recordings. I'm often adding backgrounds to talking head shots in documentaries for exactly that reason, to add some world to what other wise is a fairly sterile shot.

To back up Richard a bit, I have cleaned up thousands of hours of production and have some pretty decent tools and a lot of experience and you really just never know if you can make it work till your in there working it.

With the right tool bird tweets are pretty removable. Car horns, depends on if they are static and short or moving (doppler) and longer.

But noise reduction is subtractive. Every pass removes some of what you want with the part you don't want. If one light pass can get you where you need to be then it can be miraculous, if it takes a bunch of passes with different tools it can be impossible to keep enough of what you want to make getting rid of what you don't worth it.

Your mic options are not great so I would use both and try to get the videomic as close as possible and if at all possible pointed away from the outside, though that is probably not possible since you want the background.

Another option that might work depending on how static the background is.

Shoot a "clean plate" of the background, then shoot the interview with the mic really close and in the shot. Then mask out the mic and use the clean plate to fill the hole. If you background is constantly changing this doesn't work at all but if it's pretty static it can work really well.

There is a thread on this list someplace where one of the posters showed this in action and it was pretty great. It was his idea I didn't think of it, but I have used it.