Trying to remove noise and have a more clear audio


Hello everyone,

I’m glad to have access to this forum. I’m new using this software and I do not know much about audio editing. I’m also not a native english speaker so I apologize for any typo or grammar. I have read several post regarding the topic I mention in the subject. I’m trying to edit some speeches from a retreat and make them sound better than the original as it has alot of background noise and a Hum, that I suppose is originated from the way the speech was recorded. So basically what I have done is:

  1. Apply the notch filter in the different frecuencies that were identify by spectrum analysis in part of the track were no voice was recorded.
  2. I applied de normalized effect with the default value (-3.2db)
  3. I applied compressor with the default values (-20db; -50db; 2:1; 0,20seg; 1,0seg; both bottom boxes checked)
  4. I applied noise reduction with default value (24db; 0,00; 150)
  5. I applied equalize ( bass boost default value, and then treble boost default value)
  6. I apply amplify default value

I am sending a copy of the original record and the one after edition. I would appreciate if you could hear both of them and let me know if there is anyway to produce a better audio or if what I have done is the best I can get.

I’m very grateful for the help and support you can provide me. Since I need to duplicate the validated process in several audios.

So you didn’t record it?

Your noise reduction values are for an earlier version of Audacity. The newer versions, 2.1.0 and 2.1.1 are much better at rescues.

http://audacityteam.org/download/

Attached is the best I could do. The original volume moves and I can’t fix that easily.

If that’s close enough, I’ll post how I did it. There’s one custom voice filter (needs to be installed), five different Notch Filters, Noise Reduction and Normalize.

It’s super important the profile step in Noise Reduction be done from a place with Noise Only! If there is any voice or natural sound in the selection, Noise Reduction isn’t going to work very well. This is the step that kills you with a high noise show. You can’t find a place with pure noise.

Koz

That is badly afflicted by mains-hum . There are plugins for Audacity which can remove it ,
see … https://forum.audacityteam.org/t/multiple-notches-with-nyquist-prompt/7583/10

DeHummer settings used.png

Hello Koz and Trebor,

To answer your question Koz, I did not do the recording

My Audacity software version is 2.1.1

Koz,
I will appreciate if you could send me the steps to be followed to improve the recording. I think you obtained a very fair result. I couldn´t have reach it by myself. I´ll take in account your advise for the noise profile… actually I tried to do it that way in my version, but I’ll keep that in mind as an important issue.

Thank you for your help!

Kind regards,

Put a copy of the attached file “Mains dehummer 2-0.ny” in the Audacity plugins folder …
http://wiki.audacityteam.org/wiki/Plug-ins#How_do_you_add_plug-ins_to_Audacity.3F

Then use the settings shown in my previous post.
Mains dehummer 2-0.ny (998 Bytes)

I applies Steve’s voice (rumble) filter.

Download and uncompress the filter.
http://www.kozco.com/tech/audacity/Documents/LF_rolloff_for_speech.xml.zip

Install it in the Equalizer tool.

Adding Audacity Equalization Curves
– Select something on the timeline.
– Effect > Equalization > Save/Manage Curves > Import
– Select LF_rolloff_for_speech.xml > OK. (it won’t open the ZIP. You have to decompress it)
– LF rolloff for speech now appears in the equalization preset curve list.

Apply it to the work.

LF Rolloff (rumble filter)
– Select the whole clip or show by clicking just above MUTE.
– Effect > Equalization: LF Rolloff for speech, 8191 Length > OK



I did that mains hum thing manually, one tone at a time. Steve’s filter removes the first tone, 60Hz, so that’s one you don’t have to do.

Effect > Notch Filter: Frequency 180, Q 12 > OK
Repeat for all these tones:
180 (see above)
300
420
540
660

I followed that with Noise Reduction.

Noise Reduction
– Drag-select Room Tone, silence or the flat area between spoken phrases.
– Effect > Noise Reduction: Profile
– Select the whole clip or show by clicking just above MUTE.
– Effect > Noise Reduction: Settings 18, 6, 6 > OK

By using DeHummer, you may not need that high a noise reduction value. People recording AudioBooks usually do OK with 6, 6, 6, and 12, 6, 6. Experiment. Take the old correction out before you add a new one.

Then bring the volume up.

– Effect > Normalize: [X]Remove DC, [X]Normalize to -1 > OK

Koz