Hello there, I am trying to restore this old song from a 1930’s German movie. I tried using equalization, bass and treble, etc… But the audio still remains scratched up, especially with the vocals at the end. Can anyone help me restore this song and make it sound clear? Thanks!
In general there’s only so much you can do. You might be able to improve the sound but you can’t expect to get something that sounds like a modern digital recording… There’s nothing you can do about distortion and often there’s not much you can do about noise.
With equalization, boosting the low-mid frequencies around 200-300 Hz (or perhaps a little lower lower) can bring-out vocal resonance. Boosting* the higher frequencies above around 4kHz will bring-out the “T” an “S” sounds which can help intelligibility and it will also bring-out the 'brightness" of horns & cymbals, etc. Unfortunately, boosting the higher frequencies will also accentuate crackle & hiss.
In an older recording there won’t be any deep bass or very-high frequencies other than noise. So you can experiment with turning-down frequencies below around 100Hz and above around 10kHz to see if that helps reduce the noise.
You can try regular [u]Noise Reduction[/u] but if the noise is bad, “The cure can be worse than the disease”. Noise reduction works best wen you have a constant low-level background noise… It works best when you don’t really need it.
If you have pops & clicks (which could come from the film audio or from a record… They didn’t have tape in the 1930’s) you can try [u]Click Removal[/u] or [u]Repair[/u]. Or there is a free program called [u]Wave Corrector[/u] that’s intended for digitized vinyl record clean-up but it can help with clicks & pops no matter the source.
Whenever you boost anything you can potentially push the levels onto clipping (distortion). Audacity itself won’t clip but WAV files and your digital-to-analog converter are hard-limited to 0dB. After any editing/processing that can boost the levels it’s a good idea to run the Amplify effect (or the Normalize) effect before exporting to make sure the levels don’t exceed 0dB.