What's your go-to technique for cleaning up background noise in a recording without losing the essence of the audio?

Apart from the obvious RX answers in here, I go with a free tool.
This fantastic ReaperDenoiser saved me a lot of times. https://github.com/micsthepick/REAPERDenoiser

Here's a documentation why it's working much better then ReaFir: https://www.neilbickford.com/blog/2020/02/02/a-real-time-jsfx-audio-denoiser-for-reaper/

Here’s my go-to technique:

Start with a Noise Print: Use software like Audacity or Adobe Audition to sample a section of the recording where only the noise is present (like a silent moment). This becomes your "noise print."

Apply Noise Reduction: Use the noise print to guide the noise reduction tool. Adjust the intensity carefully—too much reduction can create an unnatural, robotic sound.

EQ Adjustment: Sometimes, specific frequencies carry more noise. Using an equalizer, I gently reduce those frequencies without affecting the voice.

Use a Noise Gate: This tool can cut out low-level background noise during silent parts of the audio without impacting louder, important sounds.

Manual Touch-Ups: In some cases, manually silencing or fading noisy parts between speech helps keep things natural.

There are several plug-in tools to clean up noise in recordings, my favorite being Izotope's RX. I usually solve quite a few recording problems with excellent results. Among them, I have to name one that I'm always using to solve noise problems in vocals: I'm talking about RX De-Click and mainly (my favorite, I have to say it haha) RX- De-Crackle. This last one is a wonderful tool to clean the sound that can generate the mouth of a singer, personally I don't like that in the recording and with this tool it eliminates it completely with its excellent algorithm without losing important information of the vocal recording.

My go-to technique for cleaning up background noise while preserving the clarity and natural feel of the audio involves a few key steps:

    1.    Noise Reduction with a Noise Profile
I begin with a noise reduction plugin, like iZotope RX or Adobe Audition’s noise reduction tool, to capture a “noise profile” from a silent part of the recording. This allows the software to isolate and reduce only the unwanted background noise.
Tip: I keep the reduction intensity moderate to avoid artifacts that can make the audio sound hollow or unnatural.

    2.    Using a High-Pass Filter
For low-frequency rumble or hum, I apply a high-pass filter, typically between 80–120 Hz. This removes low-end noise without affecting the voice frequencies.
Tip: I adjust the cutoff frequency to retain the fullness of the voice, especially if it’s a deeper vocal.

    3.    Precision EQ for Problem Frequencies
I use a parametric EQ to identify and gently reduce any specific frequencies where background noise stands out, like air conditioner hums or room resonances. This is usually in the 100–400 Hz range or occasionally higher frequencies.
Tip: I make narrow cuts to avoid affecting the overall tonal quality of the audio.

    4.    Noise Gate for Silent Sections
For moments of silence between phrases, I use a gentle noise gate or expander to reduce the background noise in those areas, keeping the gate threshold just above the noise floor so it doesn’t cut into the quieter parts of the voice.
Tip: Soft settings help avoid choppy transitions, making the gating sound natural.
    5.    Manual Volume Automation

If there are specific sections with noticeable background noise, I use volume automation to bring down those areas slightly, rather than relying solely on noise reduction processing. This allows for finer control without over-processing the audio.
Tip: I manually lower noise-heavy parts to maintain dynamics and avoid losing vocal presence.

My go-to technique for cleaning up background noise while preserving the essence of the audio involves a few careful steps:

1. Noise Reduction Plugin with a Noise Profile

I start by using a noise reduction plugin (like iZotope RX’s Voice De-noise or Audacity’s Noise Reduction) to capture a “noise profile” from a quiet section of the recording. This helps the software identify and filter out the specific background noise while keeping the primary audio intact.

Tip: I apply this effect subtly, setting the reduction intensity low to medium, avoiding an overly aggressive cut that could make the audio sound unnatural or hollow.

2. High-Pass Filter

If there’s low-end rumble or hum, I use a high-pass filter, typically around 80–120 Hz, to clean it up. This is especially effective on vocals, as it removes low-frequency noise without affecting voice frequencies.

Tip: I adjust the filter to just above the lowest range of the voice to retain fullness.

3. Selective EQ Cuts

Using an EQ, I look for specific frequency spikes caused by background noise (e.g., fan hums or room resonance) and apply gentle cuts only to those ranges, often between 100–400 Hz or in the high frequencies above 5 kHz.

Tip: I keep these cuts narrow to prevent them from affecting the vocal tone or any essential frequencies in the recording.

4. Gating and Expansion for Silence Management

For sections where there’s no speech or music, I use a noise gate or downward expander with soft settings. This reduces the noise floor in silent sections without impacting active parts of the audio.

Tip: I set the threshold just above the noise floor to prevent the gate from interfering with quieter audio elements.

5. Automation for Dynamic Noise Reduction

Finally, if there are specific areas with higher noise, I use volume automation to gently lower those sections without needing extra processing. This maintains the natural dynamics and avoids over-processing.

Hello everyone, it's Hill a mixing and mastering engineer based in Barcelona.

For cleaning up background noise while preserving the essence of the audio, iZotope RX is my main go-to tool. Its range of highly precise modules makes it ideal for handling different types of noise without compromising the integrity of the recording. Here’s how I typically approach it:

1. Spectral De-noise: I start with RX’s Spectral De-noise module, which is excellent for reducing consistent background noise like hum, hiss, or air conditioning. By analyzing the noise profile in quieter parts of the recording, I can create a “fingerprint” that RX will use to selectively reduce just the unwanted frequencies. This lets me clean up the track without affecting the character of the vocal or instrument.

2. Voice De-noise: For dialogue or vocal tracks, I use Voice De-noise to handle background noise in a more targeted way. It’s tuned specifically for vocals, so it does a great job at removing broadband noise while keeping the vocal tone and dynamics intact. I’ll usually start with the default settings and tweak the reduction and threshold to ensure it sounds natural.

3. De-click and De-crackle: For recordings with random clicks or crackles, De-click and De-crackle modules come in handy. These are perfect for getting rid of any transient noise without affecting the rest of the audio. I adjust the sensitivity to avoid cutting into subtle details that are essential to the performance.

4. Ambience Match: Sometimes, removing noise too aggressively can make the audio sound unnatural or sterile. RX’s Ambience Match feature lets me reintroduce a low level of the original background ambience to keep the audio sounding consistent and natural. This is especially useful if the track is part of a larger production or sequence and needs to match other sounds in the mix.

5. Manual Spectral Repair: When I encounter more complex or irregular noises, like chair squeaks or occasional pops, I go to Spectral Repair in RX. This lets me manually target specific spots on the spectrogram and remove or reduce those noises. It’s a meticulous process, but it’s highly effective for preserving the essence of a performance.

Same here, Ozone team! haha, 
Thanks for reading.

Izotope RX Spectral De-Noise is great for this. Find a small section of the noise, loop it, and then run the "Learn' algorithm. Adjust "Reduction" as to how much you want to remove before hearing artefacts. DONE!

Can't go wrong with iZotope's products. They are worth every cent. The tutorial videos included with some of them teach you a lot too. I never fully understood compression until I listened to the video included with oZone. Same goes for their other tools.