In this guide
The noise floor is the background noise present in an audio system or recording. Identify whether the unwanted sound comes from the room, microphone, connection or processing, and compare the wanted signal with that noise before choosing a fix.
The noise floor is the background noise present beneath the sound you want to record or play. It might include room noise such as a fan, electrical hiss from equipment, hum or noise introduced by processing. In a recording, it is often easiest to notice during a pause, though it can also be present underneath speech or music.
A low noise floor can make quiet details easier to hear, but a quieter pause alone does not prove the wanted voice or instrument is clearer. Listen to both the background and the wanted sound before and after any change.
Noise floor vs. signal-to-noise ratio
The signal-to-noise ratio compares a wanted signal with noise using a defined measurement method. A bigger gap generally makes the wanted sound easier to distinguish. The reading depends on what is measured, the time window, frequency weighting and level metric; a single peak reading from a pause is not a complete signal-to-noise measurement. Shure’s audio terminology guide describes the ratio as a comparison of signal and noise levels.
As an illustration, suppose a meter reports a passage’s average wanted-signal level at −24 dBFS and a comparable noise-only measurement at −60 dBFS, using the same measurement method and settings. Their difference is 36 dB. That number is an example, not a universal target: speech varies, noise can change over time, and the result depends on the measurement.
Turning up a finished recording raises the wanted signal and the recorded noise together. It makes both louder; it does not by itself improve their ratio. Compression and makeup gain can also make quiet noise more noticeable, depending on the settings and signal.
What causes a high noise floor?
| What you hear | Possible sources | First check |
|---|---|---|
| Airy hiss | Microphone, preamp, gain staging or a noise source in the room. | Record a pause, then compare with a quieter room and the same microphone setup. |
| Fan or traffic | Computer cooling, ventilation or outside sound captured by the microphone. | Move or quiet the source when practical, then repeat the test. |
| Hum or buzz | Electrical interference, a connection problem or nearby equipment. | Check connections and compare one change at a time; the audible pitch alone does not prove the cause. |
| Noise rises after editing | Level increases, compression or aggressive processing may make existing noise more apparent. | Bypass effects one at a time and compare at similar listening levels. |
Several causes can coexist. A room recording can contain both a fan and microphone self-noise; removing one does not necessarily remove the other. See how to diagnose and reduce hum for a focused workflow.
How to check a recording’s noise floor
- Record a representative test. Use the same microphone, distance, input gain and room you intend to use. Capture a normal sentence or musical phrase, then several seconds of natural pause without changing the setup.
- Listen safely and consistently. Play the phrase and pause at a comfortable monitoring level. Identify whether the noise is steady hiss, hum, a fan or intermittent events. Avoid turning monitoring up excessively to chase inaudible noise.
- Inspect an appropriate meter. Select the noise-only pause and use an audio editor or meter that reports the measurement you need. Note the meter type, duration and settings; peak, RMS and loudness readings are not interchangeable. A quiet pause may include breath, reverb tails or room sound, not just equipment noise.
- Compare the useful sound. Listen for quiet words, consonants and instrument decays. A short peak in speech and an average noise level do not provide a meaningful like-for-like ratio.
- Change one thing and repeat. Try moving away from a fan or adjusting microphone placement, then make a new recording with comparable performance and settings. Label tests so you can compare them fairly.
How to reduce noise before recording
- Reduce the source. If practical and safe, quiet a fan, close a window or move away from a noisy computer. Room reflections and room noise are different problems; acoustic treatment alone does not silence a fan.
- Improve placement. Move the microphone closer to the wanted source when appropriate, and aim it to favor the voice or instrument while rejecting noise where its pickup pattern allows. Check for plosives and changes in tone. Shure explains why the source-to-background relationship at the microphone matters.
- Set usable input gain. Record a normal performance without clipping, then listen to a saved test. Raising or lowering gain is not a universal noise fix: the result depends on the microphone, preamp and where the noise enters the chain.
- Check connections and power. Reseat cables, check compatible equipment and compare alternate routes one at a time. Stop using damaged hardware and follow the manufacturer’s instructions.
What if the noise is already recorded?
Choose a method for the sound you actually hear. A noise-profile reducer can be useful for steady noise when you have a representative noise-only section. A gate can lower pauses but generally cannot remove noise under speech while it remains open; it may also cut quiet words. A manual edit can fix an isolated click. See audio isolation vs. noise reduction and the microphone gate guide.
If a distinct voice overlaps with unwanted sound, the voice isolator can estimate a described voice from a supported saved file. Compare the isolated voice and remainder with the original, especially quiet words and consonants: separation can leave noise or alter the voice. AI WAV downloads require an account and sufficient credits, with the cost shown before download.
Use the lightest processing that solves the actual problem. Compare at similar playback levels and listen in the intended mix; a quieter background is not worth losing important words or natural musical detail.
Common questions
Is room tone the same as a noise floor?
Room tone is a recording of the background sound of a space with no intended performance. It can include part of the recorded noise floor, along with the recording chain’s own noise. See how to record room tone.
Does normalizing improve signal-to-noise ratio?
Applying the same gain to an entire recording raises or lowers both wanted signal and recorded noise together. It does not separately remove the noise.
Can a noise gate remove hiss under a voice?
A gate can attenuate quiet pauses, but noise may remain while the gate is open for speech. Aggressive settings can also remove soft syllables.