Background Noise? What Background Noise?
Technical Articles/August 27, 2013
It’s everywhere, even on our recordings. But don’t get comfortable with it. Background noise is best avoided like the plague!
For years now I’ve been recording mixing and mastering albums in big commercial studios, barns by the ocean, grass huts on tropical islands, suburban hell holes adjacent to bus stops, rural properties surrounded by tractors and cows, and every other conceivable environment known to man.
But as disparate as all these environments have been, they’ve all had one thing in common: background noise.
As distinct from noise floors common to consoles, preamps, microphones and analogue tape machines, background noise is a difficult thing to eradicate. Unlike sounds commonly referred to as tape ‘hiss’ or earth-loop ‘hum’, which tend to be predictable, consistent and treatable, most background noises tend to be made up of ‘incidents’ that are much harder – sometimes impossible – to eradicate later. If I need to minimise ‘hiss’ from a sound, I can knock that on the head relatively easily with quality noise reduction. But ask me to eradicate the sound of a light plane flying over the barn where you recorded a vocal overdub? Forget it.
LOCATION, LOCATION, COMPRESSION
Recording an album on location is perhaps the perfect example of where these sorts of sounds can creep in and undermine your work. Location recordings typically occur in buildings with minimal or non-existent sound control, and a dearth of outboard equipment like compressors and EQs.
The recording ‘isolation’ methods used here tend to be little more than blankets over windows, distance from civilisation, and blind luck. So if a pinecone lands on the tin roof during a quiet acoustic guitar overdub the take is probably abandoned and redone. But if a car goes past in the distance the take is often kept, either because at the time no-one heard the car go by, or it was low enough on the recording that the problem seemed minimal.
And that’s the issue in a nutshell. Most of the background noise on location seems just low enough to be tolerable, especially if you’re in denial because the environment around you is ‘just so amazing’!
But how do you define ‘tolerable’, especially when there’s less than ideal monitoring for the session? Do you listen through speakers turned down low because otherwise they’ll spill into the tracking room? In that circumstance it’s very difficult to tell if the sound you’re hearing is already in the room, or coming out of the speakers.
But the problem isn’t so much how ‘tolerable’ that distant car, that crow in the tree or that cow in the paddock is during tracking. The problem is how loud they’ll all be once the mix and mastering engineers have done their jobs.
If you’re recording on location you will almost invariably be tracking with minimal compression… sometimes none. Initial track laying in these situations tends to be very dynamic – which sets up a false sense of just how low the background noises around you will ultimately be.
It’s only when you take the recording to a mixing environment and add compression that the once ‘tolerable’ amount of traffic noise suddenly becomes a real problem for which there is no real solution – well, at least none that doesn’t substantially compromise the mix in some way.
NOISE: FLOOR & BACKGROUND VARIETIES
If you’re a tracking engineer, it’s vitally important to recognise the distinction between noise floors and background noise. The former can be treated during mixing and mastering, the latter not so much.
If you’re recording in an environment where inconsistent noises surround you day and night – cars, birds, planes, crickets, waves etc – figure them all to be more than twice as loud as your ears hear them in the room. That’s how loud they’re likely to be once the mixing’s done. Don’t just shrug your shoulders and pretend the problem doesn’t exist. Do something about it now and you’ll be fine. Ignore the problem until mixdown and you’re in for a nasty shock.
The first thing to do is get real about the tone and dynamic range of your recordings. If you’re tracking with little or no compression, chances are you’ll almost certainly use some during the mix, whereupon the background information will grow louder. If you’re recording with mellow room mics that will require some brightening up during the mix, the background noise will be exaggerated by that process. If you’re recording very quiet instruments like soft tablas or acoustic guitar the background noise will be proportionately louder even before you add dynamic control…
Place these types of mics and instruments away from the worst aspects of the background noise wherever possible. If you’re unsure of where that might be, the best way to figure this out is to EQ and compress the mics hard during the setup phase, to make the background noise more apparent.
If you’ve chosen an environment that’s not so much ‘noisy’ as ‘occasionally disrupted’, the solution is to be acutely aware of these incidents when they occur. It’s no good if the insidious background noises are overlooked or missed during tracking… they won’t be during the mix.
MIC THE ROOM, & COMPRESS
Get a mic – preferably one you can switch to ‘omni’ – and place it in the middle of the room so it’s basically picking up everything and everyone. (It can double as a talkback mic in most cases too if you like.) Set this mic up with a recording chain that includes a decent compressor and reduce its dynamic substantially – say 10 or 15dB. Record it too if you want, but more importantly, feed this channel to your monitoring while you’re tracking. Don’t send it to the musicians… their job is to play well; your job is to record them well.
The idea is that you should be far more aware of the background noises that surround you than the musicians. That way you can detect disruptive sounds if and when they occur, and make an on-the-spot judgement about whether they’re tolerable or not.
If you can avoid the worst incidents of background noise your recording session will be far more successful than if you’d simply turned a deaf ear to the problem.