In audio engineering, the noise floor is the sum of all the noise that a recording setup measures when you’re not running a signal through it. That includes noise from ground loops, interference, electromagnetic waves, wireless interference, and equipment noise.
Today’s blog post is all about how to optimize the noise floor to get your mixes sounding clear, powerful and professional. This is the 'boring' stuff that separates the amateurs from the pros!
What Is Noise Floor?
First things first…
Noise floor refers to the level of noise that is present in an electrical circuit or component. This noise can take the form of a hum, hiss, rumble, or other low-level sounds.
In other words, the amount of noise generated by the device itself with no signal present.
It is typically measured in decibels (dB) and can be produced by various factors (more on that later).
Why is this important?
This unwanted noise is present due to the laws of physics. Furthermore, the noise floor of a system will dictate how well it can handle weak signals. If the noise floor is too high, it will drown out weaker signals and make them less prominent.
Signal-To-Noise Ratio
Another important term is “signal-to-noise ratio”, or SNR. This is a measure of the level of the wanted audio signal compared to the level of background noise.
As with noise floor, SNR is usually expressed in decibels (dB). The higher the number, the better the SNR.
For example:
A specification for a microphone might say that it has an SNR of 60 dB. As dB is a logarithmic scale, this means that the level of the wanted signal (the sound from what you are trying to record) is 1024 times higher than the level of any background noise.
Similarly, a preamp with an SNR of 90 dB means that its output signal will be 32768 times higher than the noise coming into its input.
Good SNR values are important when recording or amplifying audio signals. So what is a “good” signal-to-noise ratio? Microphones with an SNR of at least 80 dB are considered satisfactory.
What Causes Noise?
Ground Loops and Electrical Noises
Ground loops and electrical noise in audio recordings can be a real pain to deal with. Here's a quick rundown of what they are and how to avoid them.
Ground loops occur when there is a difference in the ground value between two pieces of equipment. This can cause a low-frequency buzz or hum in your audio recordings.
The best way to avoid ground loops is to use balanced cables whenever possible.
This type of cable has three conductors, two for the signal and one for ground. The other conductor carries the inverse of the signal, so any noise that is picked up by one conductor is canceled out by the other.
In addition, electrical noise is any unwanted signal that can interfere with your audio recordings. Power lines, fluorescent lights, and computers are all familiar sources of electrical noise.
To reduce electrical noise, you can use shielded cables and keep your recording equipment away from sources of interference.
Electromagnetic Waves
You're in your home studio, about to record the perfect take. But just as you're about to hit record, you hear a loud buzzing sound. It's coming from your recording equipment. What's going on?
It turns out that electromagnetic waves can interfere with your audio recording. WiFi routers, phones, and other devices emit these waves, and they can cause a buzzing sound in your recording equipment.
So how do you fix this? Simply move your recording equipment away from the source of the electromagnetic waves. Just be aware that electromagnetic waves can interfere with your recordings.
Wireless Interference (Wireless Microphones Only)
Wireless microphones are becoming increasingly popular in a wide range of applications, from live music venues to conference rooms.
One way to reduce interference on wireless systems is to use bandpass filters. They allow only a specific range of frequencies to pass through while blocking out unwanted frequencies.
In addition, bandpass filters can be used in both transmitters and receivers.
In a transmitter, a bandpass filter can be used to limit the bandwidth of the signal that is being sent. This can reduce the amount of interference caused by the transmitter.
In a receiver, a bandpass filter can be used to select only the desired signal from among the many signals that may be present.
Equipment Self-Noise
As opposed to interference, self-noise is the noise that is generated by audio equipment itself. It can be a major problem when recording music or other audio, as it can make the recordings sound muddy and unclear.
There are a few main culprits when it comes to self-noise in audio equipment.
Microphones, especially condenser mics, are one of the biggest offenders. Why? They have sensitive components and are often the first link in the chain. Additionally, they can amplify any noise that they pick up.
Audio interfaces with cheap preamps are also common causes of self-noise.
The good news is that self-noise can be greatly reduced by using high-end preamps and premium microphones. These devices are designed to minimize self-noise and provide crystal-clear recordings.
So don't be afraid to invest in quality gear - it will pay off in the long run!
Other Factors That Impacts Noise Floor Negatively
Recording With Low Gain Input
When the input gain is set too low, it can result in an increased noise floor. This is because there is not enough signal present to mask the background noise.
As a result, the noise floor becomes more prominent. In this case, you should increase the gain to allow more signal through. Furthermore, this will increase the signal-to-noise ratio.
Compressing The Dynamic Range
An audio compressor can raise the noise floor in a recording by compressing the dynamic range of the signal. In other words, enhance the softest parts while reducing the loudest parts of an audio signal.
This process can increase the level of background noise, hiss, and other unwanted sounds.
Equalizers
Let's say you recorded some vocals. You have the audio files in your DAW and you're about to process the sound with additional effects.
The first thing you do is probably add an equalizer and start cutting muddy low-end frequencies. In addition, you would want to enhance the treble to add presence and clarity.
You see, hiss and noise are also high-frequency sounds. The result? A rise in noise.
Minimizing The Noise Floor
Proper Gain Staging
Gain staging is the process of setting the optimal gain levels for each stage of your signal chain. By doing this, you can maximize your signal-to-noise ratio and minimize noise floor.
Gain staging is an important part of getting the best sound quality possible. By setting the levels correctly, you can ensure that your signal has the least amount of interference and background noise. This will result in a cleaner, clearer sound.
If any stage in the signal chain is too loud or too quiet, it can throw off the entire recording. That's why it's important to take the time to set levels correctly before hitting record.
Noise Gates
A noise gate is a software, commonly used in a digital audio workstation (DAW) to mute a signal when it falls below a certain threshold. The purpose of using a noise gate is to eliminate unwanted noise and make recordings sound clear.
To achieve this, the gate must be set at the right threshold level so that only the unwanted noise is muted while the desired signal is allowed to pass through.
If the threshold is set too high, then parts of the desired signal will be muted along with the noise. On the other hand, if the threshold is set too low, then the noise will not be fully eliminated.
Noise Reduction Software
Noise reduction software is a type of audio editing software that is used to remove unwanted sounds from audio files. These software programs use algorithms to restore damaged audio files or simply improve the quality of an audio file.
De-noise algorithms are used to identify and reduce background noise, while restore algorithms can improve the quality of damaged or noisy audio.
Izotope RX is a popular noise reduction software that offers both de-noise and restore algorithms.
Conclusion
The noise floor is an important consideration when recording audio. It can be the difference between a clean, professional recording and one that sounds amateurish.
By understanding what the noise floor is and how to manage it, you can ensure that your recordings are crystal clear.
