White Noise (I think?)

Special Interest Groups Audio Processing
1

Hi everyone. I am a newbie at audio editing (but really enjoying getting to know Audacity).

I took a video off YouTube (through embed code i.e. I got an .avi file for my efforts). What do I know, but I think the recording equipment must have been of quite low quality. The video is of a student in social work doing a practice interview, and I think the mic/recorder must have been put at a fair distance…perhaps to try to minimize the artificiality of the situation. What has reseulted is very low amplitude/volume with loud “white noise” (like one used to get when a TV station went off the air - a pretty loud, aggressive buzzing that does its best to make the dialogue difficult to hear.)

I managed to get the audio from the video into an .mp3 file using other software (Power Sound editor). I was really hopeful that Audacity’s NOISE REDUCTION would do the trick, but not at all. There were a few seconds of loud buzzing “silence” in the file, so I sampled this, but it didn’t work. I think I got less volume and a small reduction in the buzzing, but I think they were proportionate to each other.

Does anyone have any ideas about what I can try? (…and if anyone knows how I can reintegrate a hopefully improved audio track back with the video, I would be very grateful.)

Thanks so much.

Judy

Judy

2

If the noise is bad, there’s not much you can do… :frowning: Noise reduction works best when you have a constant low-level background noise… i.e. When you don’t really need it. If the noise is bad, “The cure can be worse than the disease.”

On-location movie dialog is always re-recorded and lip-synched in a soundproof studio, because even with modern professional software, the noise cannot be removed. If you really wanted to make a professional production out of this, that’s what you’d have to do…

You may be able to reduce some of the noise with the Equalizer, by filtering-out the highest frequencies (above ~5khz) and the lowest frequencies (below ~300hz) while leaving most of the mddle voice-frequencies. But, there will be lots of overlap… You will still have noise, and if you filter-out too much you will filter-out the voice “clarity” too. So, you’ll have to experiment.

“Buzzing” is often related to to the power line frequency (60Hz in Ontario). A narrow notch filter at 60Hz, and notch filters at the 60Hz harmonics (120Hz, 180Hz, 240hz… may help). Start with 60Hz and 120Hz, and if that helps experimetng with notching-out the higher harmonics. Since a notch filter only affects a narrow band of frequencies, it shouldn’t affect the voice too much.


Since this is a video, the best solution might be subtitles.