Use a Free Plugin to Remove Background Noise from Dialogue

In other posts we've gone in depth learning how to get rid of background noise using iZotope RX's spectral de-noiser and standalone noise gates.

But what if you don't have access to the $400.00 iZotope software and still have background noise problems to clean up in your dialogue recordings?

After all, background noise is a very common problem in podcasts, sermons, voice-over for video and audiobook recordings.

Especially if you're recording at home, it's difficult to get away from some degree of background noise.

So, what's the solution?

Enter the powerful and completely FREE Bertom Audio Denoiser Classic plug-in.

But what makes this denoiser plug-in so special and how do you use it to clean up your dialogue recordings?

Why It's So Special

The Bertom Denoiser Classic plug-in really shines for cleaning up background noise in dialogue recordings for a number of reasons.

It's a highly useful tool with a beautifully designed user interface focusing on ease of use with its simple, clear layout.

If you don't have a denoising tool for your voice recordings yet, grab this one right away (and please consider supporting the fine work of the developer).

^{[ The Bertom Denoiser Classic ]}

Let me explain some of the excellent points of the denoiser:

1. High quality denoising:

• it does a fantastic job of cleaning up the background noise in your dialogue recording while leaving your spoken words sounding clear
  
  
• it doesn't leave artifacts (unwanted sounds) behind after it works to remove the noise (some noise removal tools leave a "watery" sounding quality to the audio after removing the noise)
  
  
• related to the last point, you can get transparent results with it (a very important part in editing your dialogue recordings)...
  
  
• transparency means it won't be obvious that the audio was processed...
  
  
• typically, this is what you're aiming for when editing voice recordings (for video, audiobooks, podcasts etc.)...
  
  
• and that's because clear, intelligible words are the goal for dialogue recordings

NOTE: to get transparent results with this denoiser plug-in, you do need to configure it properly to fit the particular problem noise in your dialogue recording (SEE HOW BELOW).

2. Simple and clearly laid out user interface:

• it's easy to find exactly what you need on the plug-in - it's built for functionality...
  
  
• it doesn't require a lot of fussing with menus, knobs or switches to get things going - just some sliders and your ears!
  
  
• wonderfully, it can be resized larger to make individual adjustments easily...
  
  
• or it can be resized smaller if your screen space is limited
  
  

NOTE: do be careful not to change the frequency area of the lowest or highest bands (25 Hz or 16.0 kHz) unless you know what you're doing (see below):

^{[ Bertom Denoiser Lowest and Highest Band Settings ]}

More advanced users may want to adapt the bands to specific frequency trouble spots.

But for beginners or if you want to keep it simple:

• leave the lowest and highest bands as they are (set at 25 Hz and 16.0 kHz)...
  
  
• and that's because changing either of those bands will automatically adjust all the other bands...
  
  
• see below for an image of the default setting for all 6 bands, since there's no "default preset" for the plug-in if they are accidentally changed (25 Hz, 91 Hz, 331 Hz, 1.2 kHz, 4.4 kHz, 16.0 kHz):

^{[ Bertom Denoiser Band Default Settings ]}

 3. Don't need a sample section of "only noise" to train it:

• many noise reduction tools won't work unless you have a sample or area of "only noise" in your recording to teach the noise reduction software what to remove...
  
  
• however, the Bertom Denoiser will remove background noise without any sample of noise at all - no problem!
  
  

4. Adaptable for different noise problems:

• as you saw above, the frequency area of the bands can be adjusted by moving the lowest or highest band...
  
  
• this makes the denoiser quite flexible and adaptable to a wide variety of background noise problems (including beyond spoken words)
  
  
• bear in mind that adjusting the bands might make operating the denoiser plug-in more complex...
  
  
• and you can still get wonderful results in dialogue recordings leaving the bands in their default state
  
  

5. Low-cost noise reduction tool:

• let's not forget the most practical aspect - this high quality tool is offered through a pay-what-you-want system...
  
  
• so you can have it for FREE or you can support the hard work and expertise of the plug-in developer and pay something fair for a fantastic tool

How To Use It

The Bertom Denoiser Classic doesn't include a user manual unfortunately.

And I haven't been able to locate one online (except on Scribd, which is not a good option since it blocks out portions of the manual as you try to view it).

But no worries - that's why you have me to figure the plug-in out for you and hopefully save you some time and frustration!

1. First, pull up the denoiser plug-in with your dialogue recording in your preferred DAW:

• make sure the HF Bias button on the right side is turned off (green is "ON" | white is "OFF")

2. Next, pull all 6 sliders all the way down to -24 dB using the white arrow controls on the left (see below):

3. Continuing, pull the threshold all the way up to 0 dB and start playing your audio through the plug-in:

4. Now you'll hear the words very faintly with the threshold at 0 dB:

• next, pull the threshold down a bit to the top of the dark gray level area that you'll see activating in relation to your spoken words

• you should start to hear the spoken words come through a little more loudly and clearly (but still somewhat muffled sounding)
  
  

• make sure the threshold is at the top of the dark gray level area (not the light gray area toward the bottom of the threshold meter)
  
  

5. Starting from left (lowest) to right (highest), you're going to pull each of the 6 sliders all the way up one by one into the red area:

• you'll pull each one to +6 dB separately (one at a time) listening to each one for background noise
  

• in this way, you'll judge where each slider / band needs to be set for the best noise reduction
  
  
• at this point you'll need to bring your overall volume up to start listening for the lower level background noise behind your spoken words
  
  

6. Begin by pulling the leftmost slider (25 Hz) all the way up (into the red area):

• this frequency area would sound very low (if you can hear it at all)
  
  
• most likely you won't hear much of anything because it is so low - 25 Hz
  
  
• set the slider at 0 dB by double clicking the white circle since we hear no noise

7. Now pull the next slider (91 Hz) all the way up (into the red area):

• you should hear a very low, muffled sound in the 91 Hz region, but listen carefully for any persistent background noise...
  
  
• bring your listening volume up some more if needed to hear the noise in the background
  
  
• especially listen for noise in any gaps between your words
  
  
• if you hear some noise, bring the slider down a bit (into the green area) to reduce the noise...
  
  
• around -2.5 to -3 dB (more or less depending on how much noise you hear - sometimes I had it down as much as -5 dB)

8. Pull the next slider (331 Hz) all the way up:

• listen again for background noise behind the words and between phrases
  
  
• if you hear more noise than in the last slider / band, pull this one down even more to reduce the noise more than the last slider
  
  
• in my voice-over for video project, I pulled this one down around -6 dB 

9. Now pull the next slider (1.2 kHz) all the way up:

• I heard less noise in this slider / band than the last one, so I pulled it down a little less...
  
  
• only to -4.4 dB (but on other voice recordings it ended up around -10 dB!)
  
  
• again, adjust up or down depending on how much background noise you hear
  
  

10. Pull the next slider (4.4 kHz) all the way up:

• I found more noise in this area than any of them yet...
  
  
• this was the main problem area for noise, so I brought the slider down further: around -15 dB

11. Finally, pull the last slider (16.0 kHz) all the way up and listen for noise:

• I heard some, but not nearly as much as the previous slider / band, so I pulled it down much less...
  
  
• somewhere around -3.5 or -4.5 dB (I settled on -3.5 dB)...
  
  
• on other dialogue recordings, I heard more background noise in this area and pulled it down to -12 dB
  
  

12. Yahoo! You're done with the hardest part - your noise reduction bands are mostly set:

• now you need to turn on the HF Bias button located on the right side (green is "ON")
  

• the HF Bias setting probably focuses the plug-in on the midrange and upper frequencies in some way...
  
  
• but in practice, I've noticed that it seems to bring out or preserve the frequencies that give clarity and intelligibility to your dialogue...
  
  
• without the HF Bias on, the denoiser tended to make my dialogue recordings sound more dull as it reduced the noise
  
  

13. Continuing, pull the threshold down slowly and you'll hear your spoken words start to sound clear:

• keep pulling it down until you hear your words clearly AND you start to hear background noise as well...
  
  
• now, slowly pull the threshold BACK UP until the background noise disappears AND the quality of your spoken words sounds clear and natural...
  
  
• this tended to be somewhere in the -62 to -67 dB area for my dialogue

14. Listening:

• finally, play your audio and turn the whole plug-in "off" and "on" using the "power button" on the lower right-hand side

• LISTEN to what the denoiser is doing to the background noise and your words as you turn the plug-in "off" and "on" - which one sounds better?
  
  
• the trick is to find the sweet spot between getting rid of the noise while maintaining the natural sound of your voice-over for video, audiobook or podcast
  
  
• so do listen carefully before committing to the changes...
  
  
• even try out different headphones or speakers in addition to what you're normally using to get a better picture

15. After you've listened, make your final adjustments to get your dialogue audio sounding its absolute best:

• if you want less noise, bring the threshold up just a little (you can even input the exact number you want - for example from -65 dB to -64 dB)
  
  
• in contrast, if you want a more natural sound to your words, bring the threshold down just a little...
  
  
• try a small difference of just one or two dB (but it will be a compromise as you'll start to hear the background noise creep back in with the spoken words)
  
  
• SEE THE FINAL SETTINGS FOR MY VOICE-OVER DIALOGUE BELOW:

BONUS TIP: if you start to hear a subtle distortion on some of your words (like I did on one voice recording):

• try pulling the sliders that are dealing with the worst parts of the background noise up just a touch...
  
  
• for example from -15 dB to -14dB on the 4.4kHz slider above
  
  
• finally, pull the threshold down a dB or two and listen to see if this clears up the quality of your words (i.e. clear with no distortion)

Once you're happy with the sound, process the whole file and enjoy!! 

Summary

Remember, the Bertom Denoiser Classic plug-in is a fantastic and highly recommended tool for denoising your voice recordings.

You should consider using it because of its:

• high quality results
• easy to use interface
• and its low cost (FREE or pay what you want)

Finally, after following the steps above to get the denoiser set up, aim to remove the noise in your dialogue without it noticeably affecting the quality of your words.

Have YOU used the Bertom denoiser on a recent dialogue recording?

Is there another plug-in that worked well for you?

Would love to hear your thoughts in a comment below! 

Cheers, Bryan
Your Dialogue Editing Mentor