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Sounds fill our world on the macro and micro levels. These sounds create signals. If you record your vocals, for example, you’ll notice that there are background sounds. You’ll notice these background sounds even if your studio is acoustically treated. The signal created by the sum of all the sources of unwanted signals and noise sources is called the “Noise Floor.”
What is Noise Floor?
Noise floor, of course, is not the noise you create on the floor. It is more than that. It is the summation of all the unwanted signals in a measurement system. It may refer to the noise from different sources of signals.
These sources of signals include atmospheric noise and thermal noise. They even include the noise created by the components that you use to measure the level of the noise floor. They also include the black body and cosmic noise. Summing up all these signals, you come up with the noise floor.
Hence, every device or system generates noise even without a signal. And the amount of noise each device generates is also referred to as the “noise floor.” An electronic device like the amplifier, for example, can generate noise. Even a wire can generate noise. This noise, of course, is measured in decibels.
The noise floor refers to the background noise that is detectible in your recording file. You can detect it well if there aren’t other audio signals imputed into the recording file. Hence, it is pretty much annoying since you want to isolate each sound source well. So, when it comes to recording, you should decrease the noise floor. The lower the noise floor is, the better.
You cannot do much against the noise floor. Even well-wrought professional studios need to deal with the noise floor. So, if you have a home studio, you don’t have to fret much about the noise floor. This is because almost everything generates signals, including your carpet, microphones, preamps, and even your computer fans.
Does Noise Floor Affect Studio Recording?
The noise floor, of course, affects the quality of a recording. If the noise floor, for example, is high, then you would find it difficult to detect the signal you want to monitor. This happens if the noise is louder than the signal. So, during the recording, the noise floor should be decreased to the bare minimum. This will allow you to monitor your source signal well.
When recording, you want the signal source to be clear. Yet, if there is a high level of the noise floor, you would find it hard to hear the signal source. If you boost the signal source, you also boost the noise floor. So, you end up having a hard time monitoring the signal source.
The good news, however, is that we now have computer audio interfaces. These contemporary audio interfaces have a lower level of noise floor as compared to many respected mixers of old. They also provide a maximum of 50dB of gain. This means you can now apply more gain to any signal.
But first, you need to measure the level of the noise floor. The noise floor is usually measured in dBm. The dBm is a unit of measurement that indicates the absolute power level that you measure in decibels. It is also referenced to one milliwatt (mW).
The Acceptable Level of Noise Floor When Recording
The general rule is: “The lower the noise floor, the better it will be for your recording.” So, you should maintain an acceptable noise floor when doing your recording. The sound that you want to be loud should have the spectral content that is not affected by the noise floor itself.
So, if you are recording the guitar track, the sound of the guitar should be unaffected by the noise floor. If the noise floor is high, your guitar recording will not be clear. If you increase the gain, you also increase the level of the noise floor. This is because the noise floor and the sound source are not isolated. Thus, when you record the sound source on a track, you also record the noise floor on that track.
So, you need to figure out where the highest level of the noise floor is coming from. Then, keep as much distance from that source of the noise floor in terms of amplitude. The ideal thing is to keep the distance at -50dB. If the noise floor is at 100dB, it will be too loud. Hence, you will hear in your recording the sounds of amplifiers and other equipment. You should be cognizant of the scales used to measure the noise floor.
Scales for Measuring Noise Floor
There are different ways to measure the noise floor. If you use the digital system, for example, you would be using Decibels, Full Scale (dBFS) as your unit of measurement. The dBFS scale, of course, is the unit of measurement used for measuring recorded audio volume.
So, the most substantial possible sound that you can capture is pegged at 0dBFS. Now, if you lessen the sound level, the dBFS level also decreases. Hence, as it gets less noisy, the dBFS plummets from 0 dBFS to -10 to -20 and so on. The dBFS is often used for inputting and outputting signals. And it indicates the measurement at the converter stage in the soundcard that you are using.
There is another way to measure the noise floor. You can use, for example, the sound pressure level meter (SPL) to measure it. This meter measures sound signals of scale in DB SPL for speakers. This meter is often the one used to measure the level of the noise floor in studios. It is specifically used to measure ambient noise.
Ways to Determine Noise Floor
You can measure the level of the noise floor in different ways. You can use, for example, a seismograph to measure it. Seismographs can measure incidental noise like foot traffic. But you don’t need to use a seismograph in your recording studio to know the level of the noise floor in it.
You can also use a spectrum analyzer. Using a spectrum analyzer, you can pick up smaller frequency ranges that come with smaller spans.
You can’t use, of course, a voltmeter or a level meter to get an accurate measurement of the noise floor. This is because noise carries an energy that is spread over a wide frequency range. Moreover, different sources and levels of noise carry differently spectral content. Thus, you should use equipment that corresponds to how our ears perceive sounds.
So, to accurately measure the noise floor, you need to comply with the following three requirements. First, you must filter out frequencies above and below what the naked ears can hear. The bandwidth audible to the naked ear is usually between 22 Hz to 22 kHz. Next, the instrument you should use should differentiate between different noise frequencies. This process is called “weighting.” Lastly, the instrument should have the right dynamics.
The right noise floor measurement needs the use of a highly specified method. It also requires a well-defined measurement bandwidth. Moreover, it needs a weighing curve indicator along with rectifier dynamics.
You can also measure the noise floor if you know how to set up your DAW’s audio configuration. Online, you will find different sorts of spectrum analyzers. Using one of these analyzers, you can measure the noise floor and also get an expanded view of the frequency affecting your audio. You can use, for example, the parametric EQ. It is a plugin to the FL Studio.
Using your audio interfaces, you are enabled to detect noise floor once your preamp gain is set to the max, and you got nothing connected to the inputs. The noise floor, however, in your recordings are usually limited by the type of audio bit depth that you are using. So, you can’t tone down the noise floor below what the audio bit depth that you are using. However, you will get higher values because of the electronic noise within the measuring system and the device.
How To Reduce Noise Floor in Recording?
You can’t fully eradicate the noise floor because, as mentioned earlier, the world is a world of sounds. You can follow the following tips, however, to minimize the noise floor to a manageable level:
- You should choose a high-quality preamp and microphones.
- You should isolate the mics you are using from unwanted sounds.
- Treat your recording studio acoustically.
- You can use an Isobox. The Isobox is often used in high-end studios.
- You can also use an equalizer to cut the level of noise.
- Use a soundproof enclosure for your computer to reduce computer noise.
Some unwanted sounds are within the sensible range. Thus, you don’t need to reduce them. Moreover, reducing them may affect your recording. This noise within the sensible range can be lessened during the mixing process.
Before recording, you should have already addressed the source of the noise. This is because you can no longer minimize them once they are recorded. Moreover, during the mastering process, all audio signals are simultaneously amplified. Even the noise is amplified. Hence, you should achieve a level of the noise floor that is around -60 dBFS before you start recording.
There is, of course, a limitation as to how you can minimize the effect of the noise floor in your recording. Thus, you don’t need to fret much about how you can get rid of the noise floor because it is not possible. As long as you can lower the noise floor level to a manageable and reasonable level, that would be fine.