Noise is the problem you notice only after you have already recorded the perfect take. A fan hum on a vocal, a hiss on an old sample, a buzz on a guitar DI: broadband denoisers exist for exactly this. Below is a practical, problem-first guide to using a simple denoiser such as Bertom Denoiser Classic, organised around the situations you will actually face.
How simple denoisers work, in one paragraph
A basic denoiser lowers the level of audio when it falls under a threshold, working across frequency bands so that steady background noise is reduced while louder signal passes through. That makes it best for constant noise (hiss, hum, air conditioning) and less effective for sudden noises like coughs. Check the developer's official page for the exact controls in the version you download.
Situation 1: constant hiss on a vocal
- Find a section of silence, such as the gap before the first word.
- Raise the threshold or reduction control until the hiss drops in those gaps.
- Now play a sung line. If breaths vanish or the word tails sound watery, back off by a third.
- Aim for 6 to 10 dB of noise reduction, not the maximum.
Situation 2: low hum from a guitar or amp
Denoising is the wrong first tool. Hum at 50 or 60 Hz plus harmonics is better handled with a narrow EQ notch or a high-pass filter. Use the denoiser afterwards for what remains. If the hum is in the recording chain, try different power sockets and cable routes before recording again.
Situation 3: noisy old samples
Old vinyl or cassette loops carry hiss that is part of the sound. Decide whether you want it. For lo-fi tracks, leave the hiss and instead lift it as a texture. For clean tracks, denoise at 4 to 6 dB, since aggressive reduction dulls the transients of drum hits.
What to compare before you start
| Problem | Best first tool | Denoiser role |
|---|---|---|
| Constant hiss | Denoiser | Primary |
| 50/60 Hz hum | Notch EQ, high-pass | Cleanup |
| Room reverb | Re-record, or a dereverb tool | Not suited |
| Clicks and pops | Manual edit | Not suited |
| Fan or air-conditioner rumble | High-pass at 80 to 100 Hz | Cleanup for hiss part |
Order in the chain
Put the denoiser first, before compression. A compressor raises quiet noise; if the noise is already lowered, compression is cleaner. Avoid running noise reduction after heavy saturation, since the new harmonics will look like signal. The same principle of getting the level right first is covered in our gain staging article.
Rule of thumb for artifacts
- Bubbling or underwater sounds mean you reduced too much.
- Consonants sounding lispy mean the high bands were cut too aggressively.
- A gated, pumping tail means the release is too short or the threshold too high.
A quick verification routine
- Solo the difference: some hosts allow polarity inversion on a duplicate track to hear only what was removed.
- If you hear words in the removed signal, reduce the amount.
- Check on headphones and on a small speaker before you commit.
Recording tips that reduce the need
- Turn off fans and fridges. Record a 10-second room tone for later reference.
- Keep the mic 10 to 15 cm from the mouth, which lifts the voice over the noise.
- Use a pop filter and a dynamic mic in noisy rooms.
FAQ
Can a denoiser remove background voices?
No. It targets steady noise, not speech or music.
Should I use one on every track?
No. Use it only where the noise is audible, since each pass costs some clarity.
Is Bertom Denoiser Classic still free?
Confirm on the developer's official page for current price and formats.
For an alternative, see our page on another free noise reducer, and browse the free plugin collection for more cleanup tools.
Prevention beats cure
Keep a short checklist beside your recording setup: fans off, phone in flight mode, gain set so peaks reach around -12 dBFS, room tone recorded. Ten seconds of silence at the start of each take gives you clean material to judge any noise reduction against later, and it costs nothing. Combine that habit with modest reduction settings and most recordings will need only a light touch.
Worked example: a podcast voice recorded in a bedroom
Suppose a spoken-word file has a steady computer-fan hiss at about -55 dBFS while speech peaks at -10 dBFS. Chain: high-pass at 80 Hz, denoiser at roughly 8 dB of reduction, compressor at 3:1 with a 15 ms attack, then a de-esser. Between sentences the hiss should sit clearly lower, but breaths should still be audible. If the room disappears completely and sounds dead, ease reduction by 2 dB, because a little ambience makes speech sound natural. Export a 30-second sample and listen on earbuds before applying it to the whole episode.
Genre note
For sung vocals in ballads, use less reduction than for speech: quiet held notes and reverb tails are easily eaten. For electronic music, use it on field recordings and sampled textures rather than on synths, which have no room noise to remove.
Final listen
After denoising, play the file back once at a normal volume and once very quietly. Quiet playback exposes leftover hiss, while normal volume reveals damage to the voice. Choose a setting that passes both listens, then bounce.
Get Denoiser Classic from Bertom Audio
