Low hum when monitoring/recording

I am running Windows 8.1 on a Dell All-In-One machine, Audacity 2.0.6 (recent upgrade from 2.0.5 to deal with this problem) obtained via the .exe installer. I am using an ION USB turntable. The problem started after I changed from Windows Vista on an HP machine, Audacity 1.2.4, to Windows 8.1 on the Dell, Audacity 2.0.5. I did not have this problem before. When I bring up Audacity and select Start Monitoring, I get a low hum. This happens without any input and shows up in the recording. I used the Noise Removal effect, got the profile, selected the entire track, but it only worked for the couple of seconds used when creating the Noise Profile, not the entire track. Went through the FAQ’s and some of the other submissions in the forum, and I get the impression that the Noise Removal effect doesn’t work properly. (Or maybe I just don’t understand it) Any suggestions would be wonderful. Thanks

it only worked for the couple of seconds used when creating the Noise Profile, not the entire track.

That usually means the noise was changing.

Noise Removal doesn’t work with general sound or a metaphor. If you sample a voice, it doesn’t suddenly start working with all voices. If you sample a fan noise, it’s only going to work with that exact fan running at that exact speed in that environment.

Change anything and it stops working.

This kills people trying to suppress noise in a car or noise from a jet going over. Both constantly changing. It also generally doesn’t work with street or crowd noises, also constantly changing.

Is that what happened to you?


Another common problem is selection. On the second pass, did you select the whole track? If not, the original selection is likely to still be there and nose reduction will only affect that small segment.


In between songs, instead of silence, this noise seems to be the same, just a low hum, the same that is heard when monitoring is first turned on. I don’t believe it’s from an external source. On the second pass, yes, I did select the entire track hoping it would remove this noise between tracks when no music is playing. Also, during soft passages in songs, this low hum can be heard as well. Any thoughts on why the “feedback” may be happening in the first place? Thanks…Doug

It should have worked in the silent gaps between songs (assuming the sound was the same — that’s important). It will probably not work during music, dialog or singing because Audacity turns Noise Removal off during show sound to avoid destroying the quality of the performance. This is set with the Smoothing control.

I’m not as familiar with the Sensitivity control, but that can cause some portions of the show to be affected according to volume.

This is why we say by the time you realize you need Noise Removal, it’s probably too late. ACX AudioBooks says never use Noise Removal at all. Ever.

You should find the cause of the problem and fix it before you need post production fixes.