How to remove hum using audacity?

[digicube]

How to remove hum when there is no hum only section in the audio file?

I used Hum remover plug-in with settings of 1,1,100%. It removed some of the hum but not all. https://wiki.audacityteam.org/wiki/Nyquist_Effect_Plug-ins#Hum_Remover

[redwudz]

Try the 'Noise Reduction Filter. I found a fairly clean sample in the second sample.
Realize that any filtering will degrade the original audio, less is better.

[digicube]

Thanks but what if there is no clean sample. I'm trying to find an alternative, more advance way to noise reduction filter.

[redwudz]

I used this section of the file for the filtered wav in the earlier post.
I suspect the frequency of the hum varies. I tried a 'Notch' filter at 60Hz, but not much affect.
Noise Reduction seems to work a little better.

[digicube]

How about the first sample from a different audio file? How do you remove hum from that?

[redwudz]

The first sample sounds more like 'ringing', sort of like feedback from the microphone. A bit harder to get a sample.
But here's one try.

[jagabo]

Notch filter at 55 Hz. removes the low frequency hum. Follow that with the noise reduction filter (10 to 15 dB) to remove the overtones.

[digicube]

Thanks for the notch filter tip, it works better than hum remover. The trick to analyze the audio using plot spectrum and find the peak?

[jagabo]

Thanks for the notch filter tip, it works better than hum remover.

The trick to analyze the audio using plot spectrum and find the peak?

Yes, I used Analyze -> Plot Spectrum on an short section where nobody was speaking. You can also try removing each of the odd harmonics with the notch filter. You can see them on the spectrum plot too: 166, 277, 388, 498, 609, 723, 827...