Every recording system or piece of equipment has a noise floor. It correlates to how much dynamic range you’ll have in your recordings, as well as how clean or noisy the sound is.
What Is Noise Floor?
Electrical components generate a certain amount of noise all by themselves—hum, hiss, rumble, etc. The noise floor is the amount of sound, measured in decibels, that a piece of gear naturally produces when you’re not running a signal through it. In a complete setup, the noise floor is the sum of all the noise generated by individual pieces of equipment at rest.
In today’s systems, especially if you’re doing everything in-the-box, noise floors can be incredibly low—inaudible, even. Technically, it was much more important back in the analog tape days. Back then, you’d have to print everything really hot. That was to keep the recorded signal level well above all the hum and hiss of consoles, outboard gear, and tape machines.
Any extraneous background noise also contributes to the overall noise floor. If you’re working at home, the hum of your air conditioner, traffic passing by your window, birds chirping outside, and any other unwanted sounds are all part of the noise floor. Studios try to block out as much of the outside world as possible in order to keep the floor as low/quiet as possible.
How does noise floor effect recording/mixing?
To get the cleanest, most professional sounding recording, you want the noise floor low. In other words, you just want to be able to record without any unwanted noise. For home recordings, the noise floor is going to be most influenced by background noise and not so much the noise of our gear. If there’s a dog barking outside while you’re tracking vocals, Fido is now a featured artist. If it’s trash day and the workers are doing their thing out front, your recording is going to end up garbage. You get the idea…
When it comes time to mix, a big part of that process is adjusting the level of our raw recordings. There could be noise in the recording that was unnoticeable while tracking, but when we start gaining it up suddenly there’s a bird chirp, or a fan blowing, etc. Compressing a signal also raises the quietest parts up and could potentially reveal unwanted noise we didn’t hear before.
This is why it’s important to keep the noise floor as low as we can for the best sound quality. The purer the raw recording, the better the final product will sound.
Common Noise Problems
Like we mentioned above, background noise is usually the biggest culprit of driving up the noise floor when you’re recording at home. Apart from that, these are other common sources of noise that interfere with our recordings.
Ground Loops, Electrical Noise, Self-Noise
Ground loops sound like a low hum or buzz. These happen when you have a bunch of different components, all connected to each other, but individually they’re plugged into different power outlets. We use balanced cables (XLR, TRS) to avoid ground loops. Some devices have a ground lift button or switch that you can engage if you hear any sort of grounding issue. Otherwise, just try using a power strip for your audio gear to minimize the number of outlets in use.
Electrical noise could be an intermittent buzz/crackle/pop. Bad cables are a common culprit, whether that’s an IEC, XLR, TRS, TS, or anything else. Self-noise is the sound that a piece of gear generates and is frequently a spec you’ll see on things like microphones. Most modern equipment has incredibly low self-noise, so it typically doesn’t become an issue. Just be aware that every piece of gear has some noise in it.
Plosives & Sibilance
Vocal recording gets noisy just by virtue of how the human voice works. Plosives are big pops of air that hit the mic capsule when the singer hits a “p” or “b” sound. Using a pop filter mitigates them to some degree, but you can’t avoid them all. Sometimes you’ll need to go in manually after recording and clip gain plosives down, or high-pass filter them to remove the lows.
Sibilance is another harsh noise the voice naturally creates. This comes from “ess” sounds in the voice’s higher frequencies. One way to reduce sibilance on the way in is to position the vocalist or the mic slightly off-axis. In post, de-essing is going to be a must.
Interference (WiFi)
It sounds crazy—or maybe it doesn’t—but WiFi can actually interfere with your recordings. You’ve experienced it firsthand if you’ve ever set your phone near your interface, or even worse, your router near your interface. If you heard some weird sounds coming from the speakers, then you witnessed WiFi interference!
Just put your phone on Airplane mode if you sense there may be some noise creeping in.
Rumbles
Rumbles come from a lot of things. It could be from a truck driving down the street; the artist might be tapping their foot while recording; a headphone cable might be hitting the mic stand; an air conditioner may have just kicked on; and many other factors. Sensitive condenser microphones even come with shock mounts to prevent them from picking up a rumble just by being on a stand.
One way to reduce the impact of rumbles on your recording is to use a high-pass filter. Some microphones have them built-in, or you might have one on your interface or preamp to engage. That’s an easy way to lower the noise floor if rumble is a problem.
Background Noise
This is easily the worst offender and the biggest challenge. Depending on how well your studio is isolated, you might have all kinds of problems with background noise. You’ll have to work with what you’ve got, but try to isolate your recording space as best you can, or schedule your recording around quieter parts of the day whenever possible.
Also, a little bit of DIY acoustic treatment can clean up a room nicely. This can help lower the noise floor, but it’s also going to create a more ideal acoustic space for cleaner, better sounding recordings.
How to Minimize Noise Issues
- Isolate your studio/recording space. The biggest battle is against background noise. Some simple bass trapping and absorbers will help slightly with isolation, but will also clean up the sound of your room for the best sounding recordings.
- Use high-quality, balanced audio cables.
- Use common sense! Don’t record in a room with a fan blowing, a TV on, and a baby crying.
Conclusion: Noise Floor
We understand noise floor as the sound our equipment generates, as well as the sound of our recording environment. Equipment noise is generally quite low, especially since we’re not printing to tape from a console. Unfortunately, most unwanted noise is going to come from our environment, so we have to be diligent about not letting it into our music!
A little common sense, and maybe a couple tricks of the trade, will go a long way in keeping the noise floor as low as can be.