| Problem | Description | Tool |
|---|
| Broadband background noise (hiss, rustle, fans) | Constant, spread across many frequencies | Spectral de-noise with a profile |
| Mains hum | 50 Hz in Europe, 60 Hz in the Americas, with harmonics (100, 150, 200 Hz...) | De-hum, multiple notches |
| Buzz | Hum rich in high harmonics (dimmers, cables, single-coil pickups) | De-hum with many harmonics, EQ |
| Clicks and pops | Short impulses (editing, vinyl, mouth) | De-click, de-crackle, editing |
| Mouth noises | Saliva and lip smacks on vocals | Mouth de-click |
| Breaths and plosives | Breaths that are too loud, “p” and “b” sounds hitting the capsule | Breath control, dynamic HP, editing |
| Room reverb | Unwanted tail in the recording | De-reverb |
| Bleed | Other instruments in the microphone | Gate, expander, de-bleed, editing |
| Clipping | Peaks clipped during recording | De-clip |
Main tools: iZotope RX (De-noise, Spectral De-noise, De-hum, De-click, Mouth De-click, Breath Control, De-reverb, De-clip, Spectral Repair, Dialogue Isolate), Waves (X-Noise, Z-Noise, X-Hum, Clarity Vx), Accentize, Acon Digital. In FL Studio, Edison has profile-based noise removal (select a noise-only section, capture the profile, apply the denoise) and declicking.
Procedure for broadband noise reduction
- Find a noise-only section (0.5–2 s) at the beginning or in a pause.
- Capture the profile (Learn / Capture noise profile).
- Set a moderate reduction: 6–12 dB for music, up to 15–20 dB for speech. More reduction = more artifacts (metallic sound, “water,” gurgling).
- Adjust the threshold (sensitivity): the minimum that removes the noise in the pauses.
- Listen to the residue (Output noise only): if you hear parts of the voice or instrument, you are removing signal.
- Two light passes (6 dB + 6 dB) are better than one heavy one (12 dB).
Hum
- Identify the fundamental with an analyzer (peaks at 50 Hz and multiples).
- De-hum with the fundamental at 50 Hz and 4–8 harmonics, or notches with Q 20–40 at 50, 100, 150, 200 Hz (−10/−20 dB). A static EQ also removes the instrument notes that fall on those frequencies: for instruments with nearby fundamentals (bass, kick) use an adaptive de-hum.
Clicks and mouth noises
- De-click at low-to-medium sensitivity; make sure it does not blunt the attack of consonants and percussion.
- On vocals, mouth noises are fixed before compression: after compression they become louder.
- Editing clicks are removed with 5–10 ms fades and crossfades on the cuts, not with the de-click.
Breaths and plosives
- Breaths: do not remove them all, lower them by 6–12 dB (Breath Control, clip gain or automation). A voice without breaths sounds unnatural.
- Plosives: HP on the single syllable (80–150 Hz) with automation or with a dynamic HP; in RX, the De-plosive module.
De-reverb and de-bleed
They reduce the room or bleed by 3–8 dB with acceptable results; beyond that, artifacts appear. They are emergency tools: the real solution is the recording.
Order in the chain
Restoration always comes before everything else: de-noise, de-hum, de-click, then editing, then EQ, compression and effects. Compression raises the relative background noise: noise at −60 dBFS can reach −45 dBFS after 15 dB of compression and saturation.
Common mistakes
- Aggressive reduction in a single pass: “underwater” artifacts.
- Profile taken from a section that contains signal: the denoise removes part of the tone.
- De-noise on the whole mix instead of on the noisy track.
- Gate instead of de-noise on a noisy vocal: the noise opens and closes with the voice and is more noticeable.
- Removing breaths and noises to the point of making the voice artificial.
Starting settings
| Parameter | Value | Why |
|---|
| Noise reduction, music | 6–12 dB | Beyond that, artifacts appear. |
| Noise reduction, speech | 10–20 dB | More tolerance for artifacts. |
| Passes | Two light ones instead of one heavy one | Fewer artifacts. |
| Hum notch | Q 20–40, −10/−20 dB at 50 Hz and multiples | Hum removed with little damage. |
| Breaths | −6/−12 dB, not removed | Naturalness. |
| Editing fades | 5–10 ms | No clicks. |
Frequencies to watch
| Range | What to do |
|---|
| 50–60 Hz and harmonics | Mains hum: narrow notches or adaptive de-hum. |
| 80–150 Hz | Plosives: HP on the single syllable. |
| 2–10 kHz | Hiss and rustle: main region of broadband de-noise. |
| 5–12 kHz | Mouth clicks and crackle: de-click at medium sensitivity. |
Example chain
| Step | Tool | Settings | Why |
|---|
| Restoration | iZotope RX / Edison (denoise and declick) | De-hum, de-noise, de-click | Clean source. |
| Editing | Playlist / Edison | Cuts, fades, breaths | Clean track. |
| Corrective EQ | Fruity Parametric EQ 2 | HP, cuts | Clean tone. |
| Gate or expander | Fruity Limiter (gate) / expander | Range −6/−15 dB | Cleaner pauses. |
| Dynamics and effects | Compressors, reverbs | Track values | Mix work. |
How to check the result
- Noise level in the pauses (RMS of a silent section) below −60 dBFS for music, below −55 dBFS for speech before compression.
- Spectrum of the pauses: no peak at 50/100/150 Hz more than 6 dB above the floor.
- Presence band (4–8 kHz) of the track after de-noise: drop of no more than 1–2 dB (the de-noise must not remove definition).
- Track crest factor unchanged within 1 dB after the de-click (attacks preserved).